Boiler maintenance checklist: the annual service visit, plus a boiler inspection checklist (free Google Docs, Word and PDF)

Published October 1, 2026

• The checklist is free. No signup or email is asked, and the links below go straight to the file.
• Deepsel is our product. It tracks the maintenance agreements these visits belong to, and the last section says so.
• The checklist is written for trained technicians. It does not replace the boiler's manual, its rating plate, the local code or the jurisdictional inspection. Where a printed target and the manual disagree, the manual wins.

A boiler maintenance checklist is the list a technician works through at the annual service visit on a heating boiler. It starts with a safety check before anything is opened, then covers the water side (pressure, expansion tank, relief valve, low-water cutoff), the burners and heat exchanger, the gas pressures, the venting and a combustion analysis, and it finishes with the controls and a written record of every reading. This one prints the target from the boiler maker's manual next to each reading and adds a page each for condensing, steam and oil-fired boilers. Its last page is a boiler inspection checklist: the items a state or city inspector checks on boilers in commercial and apartment buildings.

Get it three ways: make your own copy in Google Docs (one click, and the copy goes to your Drive), download the Word version (.docx), or download the PDF. You can also read it in Google Docs first without copying anything. The PDF is eight pages. The job record and sections A to F, which every boiler gets, fill the first four. One page each follows for condensing boilers, steam boilers, oil-fired boilers and boilers under a certificate inspection, so a crew prints only the pages the job needs. Other equipment has its own sheet: the furnace maintenance checklist, the water heater maintenance checklist for tank and tankless heaters, and the commercial HVAC maintenance checklist for rooftop units. Every free checklist in the set is listed on the checklists page.

We read the pages that rank for this search before writing this one, and they fall into two groups. The first group is written for facility managers who run commercial steam plants. ServiceChannel's three-page PDF lists daily, weekly, monthly and annual tasks as checkboxes with a notes column.¹ FMX's annual list has eleven lines, one of which reads "Make sure water pH levels are within the proper range" without giving the range.² The National Board's "Suggested Maintenance Log Program" is the older list most of them adapt.³ Rasmussen Mechanical's printable version and mitti's boiler inspection PDF both sit behind a form that asks for a name and an email address, and Tate emails its checklist after a form.⁴⁵⁶ The second group is written for homeowners. Weil-McLain's winter checklist tells owners to consult the manual "rather than relying on a universal pressure setting."⁷ That is the right advice for an owner, but it leaves the technician without a number. HVAC.com's list puts the pressure "between 1 and 1.5 bars,"⁸ which is 14.5 to 22 psi, while the Weil-McLain, Burnham and Peerless manuals give 12 psi cold for a typical residential system.⁹¹⁰¹¹ None of the pages we read prints a CO limit, a manifold pressure, a water chemistry limit or a relief valve test interval, and none separates the boiler in a house from the boiler a state inspector visits.

Boiler maintenance and boiler inspection: which boilers get which?

Every heating boiler is due an annual service visit, and every manufacturer manual we read asks for one. Weil-McLain's manual says "The boiler should be inspected and started annually, at the beginning of the heating season, only by a qualified service technician."⁹ Lochinvar asks for service "at least annually,"¹² Viessmann for "professional service annually before the heating season begins,"¹³ and Beckett says "a qualified service technician must service this burner annually."¹⁴

The certificate inspection is narrower. A state inspector or an insurance company's commissioned inspector makes the visit, which ends with a certificate posted at the boiler. It applies to boilers in commercial buildings and in apartment buildings above a size the state sets. The model mechanical code leaves these boilers to the inspectors: the 2021 International Mechanical Code's boiler chapter does not apply to "Any boiler or pressure vessel subject to inspection by federal or state inspectors."¹⁵ The National Board's model rules exempt boilers "located in private residences or in apartment houses of fewer than six family units" and inspect low-pressure heating boilers every two years, or every year "in places of public assembly."¹⁶ The states follow that pattern with their own numbers:

The table covers the states we checked, from their statutes, rules and agency pages. The National Board keeps a synopsis of every jurisdiction's rules,³⁰ and the state's chief inspector has the final word. For a residential service shop, the practical result is that a boiler in a house almost never gets a certificate inspection, so the annual service visit is the only inspection it gets. A boiler in a six-unit apartment building or a commercial building usually gets both. Sections A to F of the sheet cover the service visit, and Appendix D covers the inspection.

Sections A to F: the annual service visit every boiler gets

The first four pages are the visit itself. Each row prints the target next to the blank. Where the manufacturers disagree, the row prints the spread, because the manual for the boiler being serviced is the one that governs.

A. Safety first

B. The water side

Cold fill on a residential cast-iron system is 12 psi in the Weil-McLain, Burnham and Peerless manuals,⁹¹⁰¹¹ and the IRC's expansion tank table assumes the same: "fill pressure of 12 psig and an operating pressure of not greater than 30 psig."³⁴ Condensing boilers set their own minimums: 12 psi for Lochinvar and Viessmann, 14.5 psi for the Burnham Alpine, 8 psig for IBC's SL G3, and 13 psi for Rinnai's I-Series, which recommends 17 to 26.^1213353637 The rise from cold to hot is the more useful reading. Weil-McLain's manual says "Too high a rise would indicate a waterlogged or undersized expansion tank."⁹

Many techs check the tank by tapping it and pressing the air valve. Amtrol's instructions are more specific: "Always check the precharge while the tank is isolated and empty of water," and set it "to match boiler fill valve setting."³⁸ Weil-McLain and Viessmann say the same in their own words, and Rinnai wants the tank 2 psi below the cold system pressure.³⁹¹³³⁷ A tech in an October 2025 r/HVAC thread on boiler maintenance dismissed the tap test: "Why don't you do it right and isolate the boiler, drain it, check the air pressure and refill it with a compressor? ... This takes me 5-10 minutes. Tapping the tank is almost worthless."⁴⁰

The relief valve is the row where shop practice and the manufacturers' instructions differ. The valve makers want the lever lifted on a schedule, the boiler makers print their own schedules, and techs know that an old valve often drips after it is lifted. The table lists what each source says.

The disagreement is about valves that drip after a test. Ray Wohlfarth, a commercial boiler contractor, wrote on HeatingHelp in 2018: "We no longer test the boiler relief valves for my customers because they always seem to leak after testing and the customer gets angry and blames us." Mark Eatherton answered with the approach the sheet uses: "I'd give them the price to replace the valve BEFORE you test it, so there is no pocket shock after the fact. If the consumer declines your offer, get their signature on your service invoice, acknowledging that you offered to test and or replace relief valve, but that the consumer declines."⁴⁶ A poster on the same forum wrote in February 2026: "If you do open a valve to test it, have a spare on hand, more often than not they drip after a test opening."⁴⁷ The row therefore has three outcomes (tested and reseated, replaced, or declined), and the declined box has a signature line in section F. The discharge pipe is checked on every visit regardless. The 2021 IMC says it must "Not terminate more than 6 inches (152 mm) above the floor or waste receptor," must not have a threaded end and must not have valves or tees.¹⁵ The 2021 IRC allowed "within 18 inches (457 mm) of the floor," and the 2024 IRC moved to the 6-inch rule.³⁴ The relief valve on a water heater has its own rows on the water heater maintenance checklist.

The low-water cutoff is the control that the National Board's accident numbers point to. Its 1996 article on the device reported that "more than two-thirds of the accidents resulting from the failure of low-water cutoff devices occurred in the Heating Boilers Steam category - a category generally associated with users such as apartment building owners."⁴⁸ Its 2001 incident report found that of 23,338 accidents over ten years, "83 percent were a direct result of human oversight or lack of knowledge," with low-water conditions and poor maintenance among the causes it named.⁴⁹ Those are the newest such figures we found on the National Board's site. The 2021 IMC and IRC require a low-water cutoff on "Steam and hot water boilers," except forced-circulation coil and water-tube boilers with a flow-sensing control.¹⁵³⁴ ASME CSD-1 exempts boilers in residences from its hot water cutoff rule,⁵⁰ so whether a given house needs one depends on the code the jurisdiction adopted. Where a cutoff is fitted, it is tested with the burner firing: probe types with the test button, float types by "opening the drain valve on the bottom of the float chamber. When the float drops in the chamber, the fuel or other source of heat should immediately shut down."⁵¹

C and D. Burners, gas pressures, venting and combustion

The combustion analysis row has two numbers that must be kept apart. The code ceiling is 400 ppm air-free: IFGC Appendix D says to "Measure the CO in the vent after 5 minutes of main burner operation" and lists "Boilers (all categories) 400 ppm air free,"³¹ BPI-1200 uses the same 400,⁵⁴ and the gas boiler standard, ANSI Z21.13, limits CO to "0.04 percent in an air-free sample of the flue gases," which is 400 ppm.⁵⁵ The manufacturers' numbers are much lower. Burnham's Independence manual says "A normal CO reading for this series boiler is less than 50ppm (0.005%). A reading of more than 100ppm (0.01%) is indicative of a combustion problem."⁵² Burnham's ES2 start-up target is under 50 ppm air-free.¹⁰ A HeatingHelp regular said the same about atmospheric boilers in 2023: "CO readings in the flue are recommended to be "Less than 100PPM" is ok to run, less than 50 PPM is recommended. ... Also the boiler should be run at "steady state" meaning its all warmed up before readings are taken."⁵⁶ None of the cast-iron or oil manuals we read prints a stack temperature target, so the sheet asks for the reading as next year's baseline. Burnham's ES2 manual says to "Note the gross flue gas temperature for future reference."¹⁰

The combustion analysis is the step that separates a service visit from a visual check. A technician wrote on HeatingHelp in 2020: "Not all HVAC technicians do combustion analysis as Jamie mentioned. Some just check gas pressure and look at the flames and call it good. You definitely don't want a tech like that."⁵⁷ An oil boiler owner described the visit he got in November 2024: "He did not touch the relief valve because "it could break, and then I'm stuck here". He did not have a combustion tool or CO2 tool. He did not look at exhaust, flue, or chimney."⁵⁸ A tech on r/HVAC who runs the analysis on every call wrote: "I print out the results and staple them to my service tag. It literally takes 5 minutes."⁵⁹ The HVAC technician tool list covers who usually supplies the combustion analyzer, the manometer and the other instruments this visit needs.

E and F. Controls, safeties and the sign-off

In section E each limit is proven in operation and its setting is recorded. ASME CSD-1's recommended schedule calls for an annual test of "high-limit and operating temperature or steam pressure controls" and an annual combustion test,⁵⁰ and IFGC Appendix D asks for low-water cutoffs, feed controls, limit controls and relief valves to be tested "in accordance with the manufacturer's recommendations."³¹ A retired service tech made the point about steam pressure controls in a 2020 thread: "Operation of the pressure controls need to be done when the boiler is firing; just tripping the switch is not a test."⁶⁰ The sheet closes the visit with three full cycles watched from the thermostat, the number the National Board gives for returning a boiler to service after lay-up.³² Section F holds the findings, the result of the visit (safe to operate, safe with repairs recommended, or shut down and tagged) and the technician's and customer's signatures.

Condensing boiler maintenance: the targets differ by make

Appendix A is the page for condensing boilers (mod-cons) and combis, and no single typical value fits all of them. The CO2 targets, the CO limits, the water limits and the direction of the low-fire setting all differ by manufacturer. Navien sets low fire at a higher CO2 than high fire, while Weil-McLain says "The low fire CO2 must be lower than the high fire CO2 values."⁴⁴³⁹ The table shows the spread in the current manuals, on natural gas.

Only the K2 manual says its CO figure is air-free; the others print a ppm number without saying whether it is air-free. The water side has the same spread, and these limits are why the sheet asks for pH, hardness, chloride and glycol readings on a mod-con:

Two of the manufacturers prohibit softened fill water: Weil-McLain ("DO NOT fill with softened water") and Burnham ("Do not fill boiler with softened water to prevent chloride contamination").³⁹³⁵ Weil-McLain also asks for the system water pH to be tested "at least annually," and the sheet has a row for it.³⁹

The burner door is where the manuals differ most on a condensing boiler visit. Viessmann and Weil-McLain require new gaskets every time ("Install new burner gasket"; "Discard old burner gasket"; "The ignition electrode gasket must be replaced with a new gasket"), while Lochinvar, Burnham and IBC reuse a gasket in good condition.^1339123536 A contractor who services Lochinvar boilers on maintenance contracts described what goes wrong in a 2025 HeatingHelp thread about a burned-out Knight: "Damaging or forgetting the gasket is what I've seen techs do."⁶⁵ The cleaning rules differ too. Lochinvar cleans the heat exchanger when the flue runs more than 54°F above the return and Weil-McLain at 50°F; Lochinvar bans metal brushes and solvents, Burnham prohibits "acid or alkali products," and Viessmann says "Do not use brushes to clean the heating surfaces."^12393513 Paul Pollets, a contractor, wrote of Viessmann's older wall-hung models: "The heat exchanger needs to be cleaned yearly or the HX is likely to have premature failure."⁶⁶ A troubleshooter on the same forum listed the full mod-con service in 2023 and added, "I do not see many techs actually do a solid service on mod-cons."⁶⁷

One make needs a separate note. Triangle Tube "has ceased operations effective November 3, 2025," and Prestige boilers built from December 2011 to April 2019 are under a February 2025 recall run with the U.S. Consumer Product Safety Commission; the recalled units have "serial number prefixes beginning with AE, PT, PA, PTE and PEA."⁶⁴ Check the prefix on any Prestige you service and write it in the findings.

Steam boiler maintenance: the water line and its controls

Appendix B covers low-pressure steam, which Section IV of the ASME code limits to 15 psi.³³ Steam is the category the National Board ties to apartment buildings and to more than two-thirds of the accidents caused by failed low-water cutoffs,⁴⁸ and most of the page is the water line and the controls that protect it.

The weekly blowdown confuses owners. In February 2026 a retired contractor on HeatingHelp answered an owner who had been told to drain a gallon every week: "Unless you have one of the float type LWCO controls that instruction is not for you. Most new boilers are equipped with a probe type electronic LWCO control. They only require annual maintenance."⁷² Ray Wohlfarth wrote of the steam cutoff: "The low water cutoff is the leading mechanical cause of boiler accidents and it should be tested regularly, opened and cleaned yearly, and I like to do the slow drain test which more closely simulates actual operating conditions."⁷³ CSD-1's recommended schedule puts the slow drain test at every six months on steam boilers,⁵⁰ and Minnesota's boiler program describes the evaporation version: with the feed off, "The low-water cutoff should shut down the burner before the water level goes out of sight low."⁷⁴

Oil-fired boiler maintenance: nozzle, pump pressure, smoke and draft

Appendix C replaces the gas train checks with the oil burner. The filter and nozzle are changed and the pump strainer is cleaned every year (Riello: "The filter should be replaced at least once a year"; Beckett: "Remove and clean the pump strainer, replace if necessary" and "replace the nozzle with one having the exact specifications from the same manufacturer"),⁷⁵¹⁴ and the settings come from the boiler maker's table:

None of the oil manuals we read prints a CO limit, so the sheet asks for the reading next to the smoke number. Beckett's GeniSys control reads a normal cad cell at "0 - 1600 ohms" and locks out in 15 seconds, and the electrodes on the AFG burner's F, L1 and V1 heads sit at a "5/32” Gap," "5/16” Above Center."¹⁴ A tech on r/hvacadvice in 2024 put the time for a full oil visit at more than two hours: "An oil fired boiler maintenance usually takes me over two hours to do it right."⁷⁸

Boiler inspection checklist: what the certificate inspector looks for

Appendix D is for boilers that carry an inspection certificate. Colorado's boiler program publishes the list its inspectors work from: the nameplate first; the relief or safety valve, which it calls "the most important device on a boiler"; the control safety devices, including the low-water cutoff, the operating control, "the high temperature limit switch with a manual reset," pressure controls, the fuel train and an emergency switch "either right outside or right inside the boiler room door"; boiler room piping, combustion air, flue connections and the expansion tank; the room itself ("Boiler rooms are not for storage of any items"); and an internal inspection on steam boilers with handholes or manholes, closed up with new gaskets.⁷⁹ New York City's review list for low-pressure boilers adds that boilers permitted after July 1, 2009 have dual low-water cutoffs, the lower one with a manual reset.²² Missouri's lay-up checklist covers the prep for an internal inspection: drain and flush, open the handholes, new gaskets, and the low-water cutoff and feeder taken apart and cleaned.⁸⁰

Most of those controls come from ASME CSD-1, the standard for controls and safety devices on automatically fired boilers under 12,500,000 Btu/h.⁵⁰ The National Board counted 26 states that adopt it,⁸¹ and the 2021 IMC and IRC point to it for boiler controls.¹⁵³⁴ Its maintenance rule is the reason the sheet asks for numbers: "Operability and set points on all devices, where applicable, shall be verified by periodic testing, and the results shall be recorded in the boiler log, maintenance record, service invoice, or other written record."⁵⁰ Michigan turns that into a document the inspector looks for: "a dated and signed service report or checklist, listing each control and safety device tested with the manufacturer's name, model number, set point, and actual operational test point."¹⁹ The CSD-1 wording quoted here is from the 2009 edition, the newest one we found published free of charge; the current edition is 2024.

Between inspections the owner keeps a log. The National Board's suggested program has steam low-water cutoffs blown down daily, hot water cutoffs tested and relief valves lifted monthly, and a slow drain test every six months,³ and the 2009 CSD-1 schedule tests the low-pressure cutoff weekly.⁵⁰ Appendix D has a row to confirm the log exists and to start one if it does not.

Inspections vary in depth. The National Board noted that in most states the inspection laws "call for inspection of water-side systems (water level controls and pressure-retaining devices), but not testing of fuel train safety devices."⁸¹ A contractor described the insurance inspector on his accounts in a 2022 thread: "This guy will spend 5 minutes per boiler. The only thing he actually does is lift the pressure relief valve handle." He still supported the program: "It gives the service person a heads up and also makes the owner realize that maintenance is needed on all boilers. But if flame sensor or such fails tomorrow, the owner will say "but it was just inspected"."⁸² The certificate inspection checks that the safety devices are there and work; the annual service visit is still the one that cleans, adjusts and measures.

The annual visit is what the maintenance agreement sells

Boiler owners compare service agreements by what the visit includes. A tech answering an owner on HeatingHelp in 2022 listed the questions to ask: "Do they include cleaning the heating surfaces of the boiler? Do they clean the burners? do they check the chimney flue and smoke pipe? do they do a complete combustion test with printed results? Do they check operation of all safety and operating controls?"⁸³ Each of those questions is a row on this sheet, and the signed sheet is the shop's answer when the owner asks what the plan paid for. A retired oil-heat contractor who priced his own plans by sampling customer records wrote that he "found that 80% of those customers never needed service calls after the maintenance was completed."⁸⁴

The office work behind that promise is the harder part. A shop with 120 boiler agreements has 120 fall visits to book before the first cold week, plus the inspected buildings whose certificates come due on their own dates. The free maintenance agreement tracking spreadsheet is the starting point. It has one row per agreement with the equipment covered, the visits owed and delivered with dates, the renewal date and the payment method, and how to track HVAC maintenance agreements explains each column. The preventive maintenance schedule template shows which units are due in which month. The plumbing maintenance agreement template and the HVAC maintenance agreement template are the contracts the visit belongs to, and the equipment maintenance log is where this sheet's readings go year over year.

Above about 80 to 100 agreements, the office's time becomes the constraint. Deepsel, our product, does that office work: it keeps the ledger of visits owed versus delivered per system, schedules and invoices the visits on the plan's cadence, sends the booking requests the plan promises and logs them, and warns you before a paid visit expires unbooked. It works beside Jobber or Housecall Pro and does not replace them. The visit itself runs on the checklists in this set: this one for boilers, the furnace maintenance checklist and the HVAC maintenance checklist.

Frequently asked questions

How often should a boiler be serviced?

A boiler should be serviced once a year, before the heating season. Weil-McLain says the boiler should be inspected and started annually, at the beginning of the heating season, by a qualified service technician, and Lochinvar, Navien, Viessmann, Burnham and Beckett all call for annual service. Owners have checks to do between visits. Weil-McLain's user manual asks for the low-water cutoff to be tested every three months and the relief valve operated every six, and a steam boiler with a float-type low-water cutoff is blown down weekly. Boilers in commercial buildings and larger apartment buildings also get a certificate inspection on the state's schedule, every one to three years depending on the state.

What does an annual boiler service include?

An annual boiler service starts with a safety check (ambient CO, gas leaks, the boiler area). The water side follows: cold and hot pressure, expansion tank precharge, the relief valve and its discharge pipe, a low-water cutoff test, air elimination, and the system water's pH, inhibitor and glycol. The technician then cleans the burners and heat exchanger, measures inlet and manifold gas pressure and the firing rate, runs a spillage or draft test and a combustion analysis with CO measured air-free, proves the operating and limit controls, and writes down every reading. Condensing boilers add the burner door, gaskets, electrodes, condensate trap and neutralizer. Steam boilers add the water line, the low-water cutoff blowdown and the pressure control. Oil boilers add the nozzle, filter, pump pressure, smoke test and draft.

What does a boiler inspection include, and which boilers need one?

A certificate inspection is done by a state inspector or an insurance company's commissioned inspector. It applies to boilers in commercial buildings and in apartment buildings above the state's size limit, most often six units, and Minnesota, Massachusetts and Washington also exempt some heating boilers below a set size. A private home is exempt in every state we checked as long as it is used only as a home: Pennsylvania's exemption holds only while no business is located in the home, and Minnesota and Texas exempt only buildings used solely as residences. The inspector looks at the nameplate, the relief or safety valve, the low-water cutoff, the operating control, a high limit with manual reset, the fuel train, the emergency switch at the boiler room door, combustion air, flue connections, the expansion tank and the condition of the room, and a certificate is posted at the boiler. Intervals for low-pressure heating boilers run from every year (Ohio externally, Minnesota, New York City, Massachusetts externally) to every two years (Illinois, Colorado, Washington, Texas) or every three (Michigan hot water boilers, Wisconsin).

What pressure should a hot water boiler be at?

On a typical residential cast-iron system the cold fill pressure is 12 psi. That is the figure in the Weil-McLain, Burnham and Peerless manuals and the basis of the IRC's expansion tank table, with a 30 psi relief valve. Condensing boilers set their own minimums, from 8 psig on the IBC SL G3 to 14.5 psi on the Burnham Alpine, and Weil-McLain says the ECO Tec should never exceed 24 psig in operation. Pressure rises as the water heats, and a large rise points to a waterlogged or undersized expansion tank. Steam boilers run far lower: Burnham sets the pressure control to cut out at 1 psi with a 0.5 psi differential, Weil-McLain says never above 10 psig, and the safety valve is set at 15 psi.

How often should a boiler relief valve be tested?

The interval depends on whose instructions apply. The Watts tag says the lever must be operated at least once a year and the valve reinspected at least every three years by a licensed contractor. Apollo/Conbraco and the National Board Inspection Code say quarterly, with a pressure test every year before the heating season. IBC says every two months, Navien says at least every three years, and the National Board's maintenance log says monthly. Old valves often drip after a test, so many shops quote the replacement before lifting the lever and have the customer sign if they decline the test. None of the valve tags we read sets a replacement age.

How much does an annual boiler service cost?

Prices vary by region and by what the visit includes. In an October 2025 r/HVAC thread on boiler maintenance, technicians posted $120 for a gas boiler service in a low-cost area, $129 to look the boiler over and run a combustion analysis, $150 for the boiler alone and $350 to $400 for the whole system, and $275 for brushing and vacuuming the heat exchanger and flue pipe with an efficiency test. The low end covers a quick look and a combustion analysis, and the higher prices include cleaning and the rest of the system.

Sources

1. ServiceChannel, "Boiler Preventive Maintenance Checklist: Tips and Tasks" and the linked three-page PDF - daily, weekly, monthly and annual checkbox lists ("Check the water level glass gauge," "Remove sludge and sentiment," "Hydro test boiler for leaks") with a notes column and no target values; the PDF downloads without a form. servicechannel.com; PDF, modified August 12, 2025, read October 1, 2026.
2. FMX, "Annual Boiler Maintenance Checklist [PDF, Excel, Word]" - eleven tasks, including "Make sure water pH levels are within the proper range" and "Clean and rebuild the low water cut-off," with no ranges or values; PDF, Excel and Word download without a form. gofmx.com, modified March 24, 2026, read October 1, 2026.
3. National Board of Boiler and Pressure Vessel Inspectors, "Suggested Maintenance Log Program" (National Board Classic Series) - "In all cases the equipment manufacturer's recommendations should be followed"; daily: "Blow down and test low water cutoffs of steam boilers (once per shift for high pressure)"; monthly: "Test low water cutoffs (hot water)," "Manually lift safety/safety relief valves and check operation"; semiannually: "Perform a slow drain test for low water cutoffs (steam)," "Test boiler safety/safety relief valves in accordance with ASME Boiler and Pressure Vessel Code, Sections VI and VII"; annually: "For gas -- check drip leg and gas strainer," "Have boiler inspected by a commissioned inspector," "Leak-test all fuel valves." nationalboard.org, read October 1, 2026.
4. Rasmussen Mechanical Services, "Boiler Maintenance Checklist- AN EXTENSIVE GUIDE" (Tim Seberger, November 20, 2023) and the "Boiler Maintenance Checklist Log" resource page - daily to annual tasks for commercial steam boilers without target values; the printable checklist sits behind a form asking for first name, last name and email. rasmech.com; resource page, read October 1, 2026.
5. mitti (by SafetyCulture), "Boiler Inspection Checklist" template page - "used for inspecting oil or gas-fired boilers before issuance of certification," answered "Safe-At Risk-N/A"; the "Download as PDF" button opens a form asking for first name, last name and email. mitti.com, read October 1, 2026.
6. Tate Engineering, "Commercial Boiler Maintenance Checklist" - "To receive our checklist, fill out the form to the right for immediate access. We will email you a copy of the checklist right away!" ask.tate.com, read October 1, 2026.
7. Weil-McLain, "Boiler Winter Maintenance Checklist" (Jadie Lee) - homeowner checks; on pressure, "consult your boiler's owner's manual rather than relying on a universal pressure setting"; "Paint, solvents, cleaning products, gasoline, and other chemicals or combustible materials should not be stored near the boiler." weil-mclain.com, published November 17, 2025, modified July 30, 2026, read October 1, 2026.
8. HVAC.com, "The Ultimate Boiler Maintenance Checklist for Homeowners" (Tom Moor) - "the ideal pressure level is typically between 1 and 1.5 bars." hvac.com, modified December 17, 2024, read October 1, 2026.
9. Weil-McLain, CGa Series 4 Boiler Manual, part number 550-100-223/0425, and the user's manual for CGa, CGi, EG and PEG boilers, 550-100-226/0425 - "The boiler should be inspected and started annually, at the beginning of the heating season, only by a qualified service technician"; annual start-up list including air openings, burners and base, heating surfaces, "Oiled-bearing circulators," "Limit controls and cutoffs," expansion tank and relief valve; natural gas inlet "Maximum: 13” w.c. • Minimum: 5” w.c. • Manifold gas pressure: 3.5” w.c.," propane minimum 11 and manifold 10; spillage test "after 5 minutes of main burner operation"; return water "at no less than 130°F"; "Typical cold water fill pressure for a residential system is 12 psi"; "Too high a rise would indicate a waterlogged or undersized expansion tank"; relief valve lever operated "AT LEAST ONCE A YEAR," valve reinspected "AT LEAST ONCE EVERY THREE YEARS"; discharge "at least 6” above the floor drain," "terminate plain, not threaded"; "Do not check for gas leaks with an open flame"; user's manual: "Every 3 Months — Test low water cutoff," "Every 6 Months — … Operate the relief valve." weil-mclain.com (CGa); weil-mclain.com (user's manual), read October 1, 2026.
10. U.S. Boiler Company (Burnham), ES2 Installation, Operating and Service Instructions 103780-13, 7/26 - annual test list including "Gas input rate to boiler," "Measure CO in vent," vent damper, "CO detector operation" and "Check ignition system safety shut-off device"; "outlet pressure of 3.5 inches water column" on natural gas and 10 on propane; start-up target "CO (less than 50 ppm, air free)"; "Note the gross flue gas temperature for future reference"; water below 120°F causes condensation that damages cast iron; cold fill "until the pressure gauge reads 12 psi." U.S. Boiler document library, read October 1, 2026.
11. PB Heat (Peerless), Series 63/64 Installation, Operation & Maintenance Manual TT8066 R22 (04/26) - "Minimum gas pressure - 5.0” W.C. when boiler and other gas appliances are running," "Maximum gas pressure - 13.5” W.C.," propane minimum 11.0; manifold 3.5 in. w.c. natural gas and 10 propane, "do not set it more than 0.3 inches plus or minus"; "Leak test all gas train joints with a soap suds solution"; "Return water should not reach the boiler return connection at less than 130°F"; pressurized "to 12 psi"; water line "about 2/3 of the gauge glass"; Hartford loop "top of the close nipple is 2 to 4 inches below the boiler normal water line"; safety valve discharge "to a maximum of 12” from the floor"; weekly "Flush float-type low-water cut-off." peerlessboilers.com, read October 1, 2026.
12. Lochinvar, Knight Wall Mount WH 55-399 Installation & Operation Manual, WH-I-O Rev Y - "Have this boiler serviced/inspected by a qualified service technician, at least annually"; Table 10A, full fire, natural gas CO2 "8.0% - 10.5%"; "The CO levels should be less than 150 ppm for a properly installed unit"; "At high fire the flame signal shown on the display should be at least 10 microamps"; "Clean the heat exchanger if flue temperature is more than 54°F above return water temperature"; "Do not use any solvent," "Do NOT use a metal brush"; "When replacing the burner, ensure gasket is in good condition and positioned correctly"; condensate "(typically with a pH from 3 to 5)"; "Hardness between 5 and 15 grains per gallon," "pH between 6.5 and 9.5," "Chlorine concentration less than 200 ppm"; "The minimum cold water fill pressure for a system is 12 psi"; "The relief valve provided with the unit is set at 30 psi"; owner schedule "Every 6 months • Operate relief valve"; relief valves "re-inspected AT LEAST ONCE EVERY THREE YEARS." lochinvar.com, read October 1, 2026.
13. Viessmann, Vitodens 100-W B1HE and B1KE Installation and Service Instructions, 6167 818 - 23 (09/2026) - "professional service annually before the heating season begins"; natural gas "CO2 content: 6.9 - 11%" over the whole firing range; "The CO emmissions shall not exceed 400 ppm" (spelling as printed); ignition electrode gap "0.25 in. ± 0.02 in." (85/120) and "0.24 in. ± 0.02 in." (150/199); "Install new burner gasket"; "Do not use brushes to clean the heating surfaces"; service steps include clocking the gas meter; "Minimum system pressure is 0.8 bar (12 psig)"; "The system fill pressure value must be equal to the expansion tank pressure value at approximately 60ºF"; antifreeze maximum 50% (B1HE) and 30% (B1KE combi). viessmann-us.com, read October 1, 2026.
14. R.W. Beckett, AF/AFG Burner Manual, Form 6104 BAFG R12, and GeniSys 7505 control manual, Form 61649 R16 - electrodes for F, L1 and V1 heads "5/32” Gap," "5/16” Above Center," "1/16” Nozzle-to-tip Spacing"; "Natural Draft Applications; typically over-fire draft is -0.01” or -0.02” w.c."; adjust air "until a trace of smoke is achieved," then "Increase the air to reduce the CO2 by 1.5 to 2 percentage points"; "Remove and clean the pump strainer, replace if necessary"; "replace the nozzle with one having the exact specifications from the same manufacturer"; "Replace electrodes if tips are rounded"; "a qualified service technician must service this burner annually"; GeniSys: cad cell "Normal (0 - 1600 ohms)," "15 Second Lockout Time." AFG manual; GeniSys manual, read October 1, 2026.
15. International Code Council, 2021 International Mechanical Code, Chapter 10, Boilers, Water Heaters and Pressure Vessels - 1001.1 exception 7: "Any boiler or pressure vessel subject to inspection by federal or state inspectors"; 1004.1: controls for boilers under 12,500,000 Btu/h "shall meet the requirements of ASME CSD-1"; 1004.3 passageways "not less than 18 inches"; 1004.6 floor drain; 1006.4 relief valves "set at not greater than the nameplate pressure rating"; 1006.6 discharge: "Not terminate more than 6 inches (152 mm) above the floor or waste receptor," "Not have a threaded connection at the end of such piping," "Not have valves or tee fittings"; 1007.1 "Steam and hot water boilers shall be protected with a low-water cutoff control," except "coil-type and water-tube-type boilers that require forced circulation of water through the boiler and that are protected with a flow sensing control"; 1010.2.1 gauge glass "midpoint is at the normal boiler water level." The 2024 edition keeps the 6-inch discharge rule. codes.iccsafe.org (2021); 2024, read October 1, 2026.
16. National Board, NB-132, "Recommended Administrative Boiler and Pressure Vessel Safety Rules and Regulations" (2004) - exempts "Heating boilers or pressure vessels which are located in private residences or in apartment houses of fewer than six family units"; low-pressure boilers "shall receive a certificate inspection biennially, except boilers located in places of public assembly shall receive a certificate of inspection annually." nationalboard.org, read October 1, 2026.
17. Pennsylvania Department of Labor & Industry, Boiler Division page, and 34 Pa. Code §3a.111 - exempt: "Boiler installations in a single-family residence (as long as a business is not located in the home) or in apartment buildings with four (4) or fewer dwelling units"; "commissioned insurance inspectors"; low-pressure steam boilers "every 24 months"; steel hot water heating boilers internally "every 48 months," externally "every 24 months"; "External inspections of cast iron boilers will be conducted every 24 months." pa.gov; 34 Pa. Code 3a.111, read October 1, 2026.
18. Ohio Revised Code 4104.04 and 4104.11 - exempt: steam and hot water boilers "located in private residences or in apartment houses of less than six family units"; "All low pressure boilers and their appurtenances shall be thoroughly inspected externally under operating conditions at intervals of not more than one year, and, except for cast-iron boilers, shall also be inspected internally at intervals of not more than three years." 4104.04; 4104.11, read October 1, 2026.
19. Michigan Compiled Laws 339.5915 and 339.5943, and Michigan LARA, "Boiler CSD-1 / Rule FAQs" - exempt: boilers "located in a private residence or in an apartment building with a capacity of fewer than 6 families"; "A low pressure steam or vapor heating boiler shall receive a certificate inspection every 2 years. A hot water heating boiler or hot water supply boiler shall receive a certificate inspection every 3 years"; R 339.5206: evidence of CSD-1 testing is "a dated and signed service report or checklist, listing each control and safety device tested with the manufacturer's name, model number, set point, and actual operational test point." MCL 339.5915; MCL 339.5943; LARA FAQ, read October 1, 2026.
20. Massachusetts, 522 CMR 4.05 - low-pressure heating boilers "shall be thoroughly inspected externally at least once a year"; hot water boilers with manholes or hand holes internally "at least once every three years," steam boilers with them "at least once a year"; exempt: "Boilers used in private residences," "Boilers used for heating purposes which carry pressures not exceeding 15 PSI and have less than four square feet of grate surface," "Boilers of not more than three horsepower used for heating purposes"; certificate "posted in a conspicuous place near where the Boiler specified is located." mass.gov, read October 1, 2026.
21. New York State Department of Labor, Boiler Safety Bureau - "responsible for the inspection of all high-pressure boilers and all low-pressure boilers, except those located in dwellings of less than six families"; "Low-pressure boilers every other year"; owners may instead "Have the inspection performed by the authorized insurance company inspector." dol.ny.gov, read October 1, 2026.
22. New York City Department of Buildings, "Boiler Compliance" page and "Annual Low Pressure Boiler Inspection - Review List" (revised 2/2015) - "The Boiler Inspection Cycle is January 1 to December 31"; reports "due within fourteen (14) calendar days"; low-pressure boilers not requiring annual inspection: "boilers in residential buildings with 5 families or fewer / a single boiler located within a single dwelling unit"; defects "corrected within 90 days of the initial inspection date"; review list: "Boilers permitted after 7/1/2009 shall have dual low water cutoffs. MC 1007. The lower LWCO shall be a manual rest device" (spelling as printed). nyc.gov; review list, read October 1, 2026.
23. New Jersey Department of Labor, Boiler, Pressure Vessel and Refrigeration Compliance page, and N.J.A.C. 12:90-4.10(c) - "Hot water heating boilers by regulation at N.J.A.C. 12:90-4 shall be inspected internally at 24 month intervals and externally at 12 month intervals. Annual inspections are necessary for all steam boilers"; boilers "serving dwellings of less than six family units or other dwellings with accommodations for less than 25 persons need not comply." nj.gov; N.J.A.C. 12:90-4.10 (Cornell LII), read October 1, 2026.
24. Illinois Office of the State Fire Marshal, Boilers FAQ - "Boilers located in private residences or multi-family buildings having fewer than 6 dwelling units are exempt from inspection"; "Low pressure boilers typically used for heating and supplying potable hot water are inspected every 2 years"; first inspections by a state inspector, later ones by the insurance company inspector. sfm.illinois.gov, read October 1, 2026.
25. Minnesota Statutes 326B.988 and 326B.958 - exempt: "buildings occupied solely for residence purposes with accommodations for not more than five families" and "hot water heating and other hot liquid boilers not exceeding a heat input of 750,000 BTU per hour";"The owner of a boiler must ensure that the boiler is inspected at least annually after the initial inspection." 326B.988; 326B.958, read October 1, 2026.
26. Wisconsin Administrative Code SPS 341.17 and 341.18 - "low-pressure steam boilers and hot-water heating boilers shall be subjected to a regular internal or external inspection at least once every 36 months by a certified inspector"; inspectors confirm "safety valves and safety relief valves have been operated or tested at least once every 12 months"; exempt: "Heating boilers located in dwelling units," "Installations at one- or 2-family dwellings." SPS 341.17; SPS 341.18, read October 1, 2026.
27. Colorado, C.R.S. 9-4-104 and 7 CCR 1101-5 - exempt: "Boilers located in private residences" and "apartment houses having less than six family units"; "ASME Section IV boilers covered by these rules and regulations shall receive a certificate inspection every two years"; first certificate inspections by a state inspector. statutes; 7 CCR 1101-5, read October 1, 2026.
28. Revised Code of Washington 70.79.090 and 70.79.240 - exempt: heating boilers "located in private residences or in apartment houses of less than six families," and "hot water heating boilers listed by a nationally recognized testing agency" with "a nominal water containing capacity of one hundred twenty gallons or less having a heat input of two hundred thousand b.t.u.'s per hour or less" where they "are not installed in schools, child care centers, public and private hospitals, nursing homes, assisted living facilities, churches, public buildings owned or leased and maintained by the state or any political subdivision thereof, and assembly halls"; "Low pressure heating boilers shall be inspected both internally and externally biennially where construction will permit." RCW 70.79.090; RCW 70.79.240, read October 1, 2026.
29. Texas Health and Safety Code chapter 755 - "Heating boilers used to heat buildings that are exclusively for residential use and that have accommodations for not more than four families are exempt"; "Steam heating boilers and hot water heating boilers must receive a certificate inspection biennially." statutes.capitol.texas.gov, read October 1, 2026.
30. National Board, NB-370, "Synopsis of Boiler and Pressure Vessel Laws, Rules and Regulations" (all jurisdictions, each entry dated by the jurisdiction) - "Synopsis data is subject to change. Users are advised to consult the jurisdiction's chief inspection officer." nationalboard.org, read October 1, 2026.
31. International Code Council, 2021 International Fuel Gas Code, Appendix D, "Recommended Procedure for Safety Inspection of an Existing Appliance Installation" (informational) - D102 ambient CO: "70 ppm or greater" evacuate and call 911; "between 30 ppm and 70 ppm" turn off sources, open windows and doors, keep a permanently installed source off until serviced; "below 30 ppm the inspection can continue"; D105.1 pilot safety: main burner gas does not flow "after 3 minutes" with the pilot extinguished; D106 boilers: "Test low water cutoffs, automatic feed controls, pressure and temperature limit controls, and relief valves in accordance with the manufacturer's recommendations," "Measure the CO in the vent after 5 minutes of main burner operation"; Table D106: "Boilers (all categories) 400 ppm air free." codes.iccsafe.org, read October 1, 2026.
32. National Board, "Lay-up of Heating Boilers" (BULLETIN, Summer 2006, updated 2024) - on restart, "witness the system cycles for a minimum of three cycles"; and "Recommendations For A Safe Boiler Room" (Fall 2010) - "The boiler room should not be considered an all-purpose storage area." lay-up; boiler room, read October 1, 2026.
33. National Board Inspector Guide, "Cast-Iron Boilers" (Wayback Machine copy of June 3, 2023; the live page now redirects) - "ASME BPV Code Section IV service restrictions limit steam boilers to pressures not exceeding 15 psi and hot water boilers to pressures not exceeding 160 psi and/or temperatures not exceeding 250°F"; overheating: "warped external sheet metal casings with scorched paint is usually a reliable indicator." web.archive.org, read October 1, 2026.
34. International Code Council, 2021 International Residential Code, Chapter 20, Boilers and Water Heaters - M2001.1.1: controls for boilers of 12,500,000 Btu/h or less "shall meet the requirements of ASME CSD-1"; M2002.4: relief valve discharge "to within 18 inches (457 mm) of the floor or to an open receptor"; M2002.5: "Steam and hot water boilers shall be protected with a low-water cutoff control"; Table M2003.2 note: "fill pressure of 12 psig and an operating pressure of not greater than 30 psig." The 2024 IRC, M2002.4.1, requires the discharge to "Terminate not more than 6 inches (152 mm) above the floor or waste receptor flood level rim." codes.iccsafe.org (2021); 2024, read October 1, 2026.
35. U.S. Boiler Company (Burnham), Alpine Installation, Operating and Service Instructions 103448-12 (8/24) - natural gas CO2 "9.9 - 8.2" high fire and "9.9 - 7.9" low fire, CO "Less than 100 PPM"; igniter gap "0.17” (4.5mm)"; "Any cleaning of the combustion chamber with acid or alkali products is prohibited. Do not use any cleaning agents or solvents"; "Inspect the burner gasket and replace if necessary"; "Annually inspect all vent gaskets"; "pH between 7.5 and 9.5. If system contains aluminum components, pH must be less than 8.5. Chlorides less than 50 ppm"; "Do not fill boiler with softened water to prevent chloride contamination"; "Minimum pressure in the boiler must be 14.5 PSI"; low water cutoff service: Hydrolevel 1100H4 "Every 5 years," McDonnell & Miller 751 "Every 10 years. Replace probe." "Every 15 years. Replace control." U.S. Boiler document library, read October 1, 2026.
36. IBC Technologies, SL G3 Residential Condensing Boiler Installation & Operating Manual 120-276E13 (August 11, 2026) - Table 14 natural gas CO2 high fire "8.9% - 10.0%" (target 9.5), low fire "8.2% - 9.2%" (target 8.7), CO "<150 ppm"; minimum flame current 1.4 to 3.2 µA by model; "When cleaning use only water, stainless steel safe cleaners and plastic bristled brushes. Do not use anything metallic"; "examine the sealing gaskets and replace if damaged"; neutralizer "If the pH falls below 6.5 the neutralizing material should be replaced"; "Minimum water pressure 8 psig"; relief valve "try lever test" "every two months"; water "pH between 6.6 and 8.5," "Hardness between 1 and 9 grains," "Chloride less than 125 mg/l"; antifreeze "between 25% and 50%." ibcboiler.com, read October 1, 2026.
37. Rinnai, I-Series Condensing Boiler Installation and Operation Manual 800000111 (3/2019) - central heating "Minimum: 13 PSI … Recommended: 17-26 PSI"; "expansion tank charged to 2 PSI (14 kPa) below the cold system pressure is required"; water "pH * 6.5 to 8.5," "Total Hardness Up to 200 mg/L," "Chlorides * Up to 250 mg/L"; antifreeze "allowed maximum concentration is 40%." rinnai.us, read October 1, 2026.
38. Amtrol, Extrol installation and operating instructions, part 9015-941 (07/25) - "Always check the precharge while the tank is isolated and empty of water"; "Check precharge pressure and adjust if necessary, charging with air to match boiler fill valve setting"; "A professional plumber should check the complete system, including the expansion tank, yearly." amtrol.com, read October 1, 2026.
39. Weil-McLain, ECO Tec Series 2 Boiler Manual 550-100-270/0924 - Figure 114, model 80 natural gas "9.25 ± 0.5 < 130 8.75 ± 0.5 < 50" (high fire CO2 and CO, low fire CO2 and CO); "The low fire CO2 must be lower than the high fire CO2 values"; flue gas "no more than 50°F higher than the boiler return temperature"; "spark gap should be 4.5mm"; "Typical running flame signal should be between 4 and 6"; "Discard old burner gasket," "The ignition electrode gasket must be replaced with a new gasket," "Replace the gas valve-to-venturi fiber washer … with a new fiber gasket"; "DO NOT use any solvent when cleaning the exchanger"; "DO NOT fill with softened water"; "Water pH between 7.0 and 8.5," "Hardness less than 7 grains," "Chloride concentration must be LESS THAN 200 ppm," "DO NOT exceed 50% antifreeze by volume"; "Test the pH of a sample of system water at least annually," antifreeze and inhibitor checked annually; "Operating pressure must never exceed 24 PSIG"; "Calculated cold fill pressure should equal tank air charge pressure"; "A separate low water cutoff is required." weil-mclain.com, read October 1, 2026.
40. r/HVAC, "Boiler Maintenance" - Excellent_Wonder5982, October 18, 2025: "Why don't you do it right and isolate the boiler, drain it, check the air pressure and refill it with a compressor? Maybe replace the valve core if glycol has damaged it? This takes me 5-10 minutes. Tapping the tank is almost worthless." Prices posted in the same thread the same day: "I'm 129 to basically look at it quick and run combustion analysis" (Short-Veterinarian27); "If I'm just checking the boiler operation itself, then I'm 150. If it's the whole system - check/flush/bleed etc, then it's 350-400 usually" (dejomatic); "$275 gets people NFS, brush and vac the heat exchanger and flue pipe, efficiency test and making any changes" (callofhonor); "I get $120 to service a gas boiler … I am in a low cost area" (ProfessionalCan1468). reddit.com, read October 1, 2026.
41. Watts, relief valve tag for the 174A, 335, 374A, 740 and M375 series (Tag 174A 0535) - "the valve lever MUST be operated AT LEAST ONCE A YEAR by the boiler owner"; "reinspected AT LEAST ONCE EVERY THREE YEARS by a licensed plumbing contractor or authorized inspection agency"; "terminate at least 6" (152mm) above the floor drain"; "No shutoff valve shall be installed between the relief valve and boiler, or in the discharge line." watts.com, read October 1, 2026.
42. Apollo (Conbraco, Aalberts IPS), Series 10 hot water relief valve tag I-270000 and Series 12, 13 and 14 steam safety valve tag I-352500 - "UNDER NORMAL OPERATING CONDITIONS A “TRY LEVER TEST” MUST BE PERFORMED QUARTERLY … PRESSURE TEST ANNUALLY PRIOR TO HEATING SEASON"; "HOLDING THE TEST LEVER FULLY OPEN FOR AT LEAST 5 SECONDS." Series 10; Series 12-14, read October 1, 2026.
43. National Board Inspector Guide, "Pressure Relief Devices" (Wayback Machine copy of February 22, 2024) - "ASME BPV Code Section IV devices can have the test levers lifted without pressure in the boiler"; frequencies are in "the National Board Inspection Code, Part 2 2.5.8"; and California DIR (Cal/OSHA), "Pressure Relief Device Inspection, Review of NBIC Part 2, par. 2.5" (J. F. Ball, updated November 2016): "Hot water heating boilers – manual test quarterly, annual pressure test before heating season." web.archive.org; dir.ca.gov, read October 1, 2026.
44. Navien, NHB-H Installation and Operation Manual (version 1.0, April 2026) and User's Information Manual (April 2024) - Table 2 natural gas CO2 8.9% high fire and 9.5% low fire, "(CO2 values must be within 0.5% of the values listed.)"; water table: total hardness "Up to 200 mg/l (12 grains/gallon)," chloride "Up to 250 mg/l," "pH 6.5 to 8.5"; "Navien recommends against exceeding a 35% concentration of glycol"; built-in low water cutoff "minimum operation pressure for this device is 6 psi by default"; "replace the neutralizing media when the pH is below 6.0"; relief valve "checked at least once every three years by manually operating the relief valve"; "The boiler should be inspected annually only by a qualified service technician." installation manual; user manual, read October 1, 2026.
45. Weil-McLain, EG and PEG Series 7 Boiler Manual, part number 550-100-225/0425 - "The control should never be set with a pressure above 10 PSIG"; "The boiler relief valve must be tested at least monthly during the heating season"; "Relief Valve, 15 PSI" in the standard equipment list; "Normal waterline is halfway up gauge glass"; "24” minimum from waterline to bottom of header"; skimming: "Continue skimming until discharge is clear. May take several hours." weil-mclain.com, read October 1, 2026.
46. Heating Help: The Wall (forum.heatinghelp.com), "Boiler Relief Valve Testing Do you do it?" - RayWohlfarth, February 15, 2018: "We no longer test the boiler relief valves for my customers because they always seem to leak after testing and the customer gets angry and blames us"; Mark Eatherton, February 15, 2018: "I'd give them the price to replace the valve BEFORE you test it, so there is no pocket shock after the fact. If the consumer declines your offer, get their signature on your service invoice, acknowledging that you offered to test and or replace relief valve, but that the consumer declines." thread; Eatherton reply, read October 1, 2026.
47. Heating Help: The Wall (forum.heatinghelp.com), "Weeping PRV." - hot_rod, February 19, 2026: "The tag attached to Watts boiler relief valves indicates testing yearly and the corrosion can render the valve inoperative. … If you do open a valve to test it, have a spare on hand, more often than not they drip after a test opening." forum.heatinghelp.com, read October 1, 2026.
48. National Board, "Low-Water Cutoff: A Maintenance Must" (BULLETIN, Spring 1996) - "more than two-thirds of the accidents resulting from the failure of low-water cutoff devices occurred in the Heating Boilers Steam category - a category generally associated with users such as apartment building owners." nationalboard.org, read October 1, 2026.
49. National Board, "2001 Incident Report" (BULLETIN, Summer 2002) - "Of the 23,338 accidents recorded over the past ten years, 83 percent were a direct result of human oversight or lack of knowledge (i.e., LOW-WATER CONDITION, IMPROPER INSTALLATION, IMPROPER REPAIR, or OPERATOR ERROR OR POOR MAINTENANCE)"; steam heating boilers caused 9,588 of them and water heating boilers 6,928. nationalboard.org, read October 1, 2026.
50. ASME, "CSD-1 - Controls and Safety Devices for Automatically Fired Boilers" product page (2024 edition, "placed on stabilized maintenance") - scope "fuel input ratings under 12,500,000 Btu/hr"; and the 2009 edition published by Public.Resource.Org - CM-110(b): "Operability and set points on all devices, where applicable, shall be verified by periodic testing, and the results shall be recorded in the boiler log, maintenance record, service invoice, or other written record"; CM-130: the owner keeps "a formal system of periodic preventive maintenance and testing" and "a detailed checklist for operator's use"; CW-120(a): low-pressure steam boilers "shall have at least two automatic low-water fuel cutoffs," one on gravity-return units in residences; CW-130(a): hot water low-water cutoff "except those installed in residences"; Nonmandatory Appendix D: low-pressure low-water cutoff test weekly, steam "slow drain test" semiannually, annually "Test high-limit and operating temperature or steam pressure controls," "Conduct a combustion test," "Perform leakage test on pilot and main gas and /or oil fuel valves." asme.org; CSD-1-2009 text (archive.org), read October 1, 2026.
51. National Board Inspector Guide, "Water Level Controls and Devices" (Wayback Machine copy of February 29, 2024) - float cutoff "tested while the burner or other source of heat is operating … by opening the drain valve on the bottom of the float chamber. When the float drops in the chamber, the fuel or other source of heat should immediately shut down"; probe cutoffs by "depressing a test switch"; the slow drain test "usually requires two people to perform this test safely." web.archive.org, read October 1, 2026.
52. U.S. Boiler Company (Burnham), Independence gas steam boiler, Installation, Operating & Service Instructions 103538-13, 1/25 - "Inspection and service should be conducted annually"; minimum inlet gas 4.5 in. w.c. natural gas and 11.0 propane; alternate orifices where manifold pressure is "less than 3.2 inches water column or greater than 3.8"; "Set cut-out pressure (MAIN scale) on the pressure limit for (1) PSI and differential pressure (DIFF.) for .5 PSI"; "A normal CO reading for this series boiler is less than 50ppm (0.005%). A reading of more than 100ppm (0.01%) is indicative of a combustion problem"; float low-water cutoff "Weekly (or more frequently if necessary). Open blow-off valve," "Five (5) Years or 100,000 switch cycles. Replace switch and float mechanisms"; probe cutoff: "If scale or contamination exceeds 0.2 inches, clean probe more frequently"; "Do not install a relief valve with a setting greater than 15 psi"; discharge "at least 6 inches above the floor"; "Do not use a check valve in place of, or in addition to, a Hartford loop on a gravity return system"; skimming "can be completed in about an hour"; boiler water chlorides "≤ 100 mg/L (ppm)," hardness "≤ 200 mg/L (ppm)," "7.0 ≤ pH ≤ 11.0." U.S. Boiler document library, read October 1, 2026.
53. PB Heat (Peerless), 211A steam boiler IOM GG8093 R5 (08/26) - "The vent system must provide a draft of at least - 0.02” w.c. (5 Pa) measured within 12 inches of the draft hood outlet"; "Pipe the header at least 24 inches (610 mm) above the normal boiler water line"; "CSD-1 recommends performing leakage tests annually." peerlessboilers.com, read October 1, 2026.
54. Building Performance Institute, ANSI/BPI-1200-S-2017, "Standard Practice for Basic Analysis of Buildings" - Table 1 "Boiler 400 ppm air free"; flue CO "taken at 5 minutes of main burner operation." bpi.org, read October 1, 2026.
55. U.S. Consumer Product Safety Commission, letter to CSA Group on ANSI Z21.13, September 30, 2015 - "the existing requirement in Section 5.5, Combustion, of ANSI Z21.13 which specifies that boiler CO emissions shall not be '… in excess of 0.04 percent in an air-free sample of the flue gases…'" cpsc.gov, read October 1, 2026.
56. Heating Help: The Wall (forum.heatinghelp.com), "Safety concerns and replacement options for a 140 co ppm 35 year old boiler" - EBEBRATT-Ed, November 16, 2023: "CO readings in the flue are recommended to be "Less than 100PPM" is ok to run, less than 50 PPM is recommended. … Also the boiler should be run at "steady state" meaning its all warmed up before readings are taken." forum.heatinghelp.com, read October 1, 2026.
57. Heating Help: The Wall (forum.heatinghelp.com), "What does annual maintenance entail?" - SuperTech, November 16, 2020: "Not all HVAC technicians do combustion analysis as Jamie mentioned. Some just check gas pressure and look at the flames and call it good. You definitely don't want a tech like that." forum.heatinghelp.com, read October 1, 2026.
58. Heating Help: The Wall (forum.heatinghelp.com), "What should be done during annual oil boiler service?" - CoachBoilermaker (homeowner), November 19, 2024: "He did not touch the relief valve because "it could break, and then I'm stuck here". He did not have a combustion tool or CO2 tool. He did not look at exhaust, flue, or chimney." forum.heatinghelp.com, read October 1, 2026.
59. r/HVAC, "combustion analysis - who's testing and who's guessing?" - OldestBeef, October 13, 2021: "I run the analysis and adjust gas pressures, fuel mixtures, replace nozzles, red tag systems, etc. as needed on every single maintenance call I do on oil/LP/ng burners and obviously all new installs. I print out the results and staple them to my service tag. It literally takes 5 minutes." reddit.com, read October 1, 2026.
60. Heating Help: The Wall (forum.heatinghelp.com), "annual boiler mud cleanout, and steam system maintenance / checking" - retiredguy, September 18, 2020: "the "pigtail" that the pressure controls should be mounted on need to be removed and cleaned annually. Operation of the pressure controls need to be done when the boiler is firing; just tripping the switch is not a test." forum.heatinghelp.com, read October 1, 2026.
61. Lochinvar, Noble Fire Tube Boiler and Combi Installation & Service Manual, Rev AM (7/25) - Table 10A natural gas CO2 high fire "8.5% - 10.5%" (target 9.0), low fire "8.7% - 9.1%" (target 8.9); "CO levels shall be less than 200 ppm"; "pH Level 6.5 to 9.5" in the table and "pH between 6.5 and 8.5" in the text; "Hardness between 5 and 12 grains per gallon"; "Chloride < 150 ppm"; "Inspect and clean the DHW flow switch filter and sanitary bypass filter." lochinvar.com, read October 1, 2026.
62. Weil-McLain, AquaBalance Series 2 Boiler Manual 550-100-325/0924 - model 80 natural gas, 0 to 2,000 ft: low fire CO2 "8.0 - 9.0," CO "<20," high fire CO2 "9.0 - 9.5," CO "<110"; "Chloride concentration must be LESS THAN 50 ppm"; "Remove and check ignitor for proper gap, 5/32”"; "Boiler water pressure switch is set for 9 psi (±2) minimum pressure." weil-mclain.com, read October 1, 2026.
63. U.S. Boiler Company (Burnham), K2 Installation Manual 105294-05 (5/15) - "CO readings should be less than 200 PPM air free"; natural gas CO2 "8.9 - 9.3." U.S. Boiler document library, read October 1, 2026.
64. Triangle Tube, "Product Recall - February 2025" and Prestige Solo Installation & Maintenance Manual A1010763 - recall "of certain Prestige Solo, Prestige Excellence and Aerco Esteem condensing gas boilers, in cooperation with the U.S. Consumer Product Safety Commission (CPSC)"; "Recalled boilers were manufactured between December 2011 and April 2019 and have serial number prefixes beginning with AE, PT, PA, PTE and PEA"; "Triangle Tube has ceased operations effective November 3, 2025"; manual: natural gas targets 9.2% CO2 high fire and 8.6% low fire, "The CO level must not exceed 100 ppm for natural gas and 150 ppm for propane gas"; water "pH level 6.0 to 8.0," "Hardness 3 to 7 grains/gallon," "Chlorides Less than 150 ppm," glycol "20 to 50 %"; built-in low water cutoff "minimum operating system pressure is 10 psig." recall page; manual, read October 1, 2026.
65. Heating Help: The Wall (forum.heatinghelp.com), "Lochinvar Knight Burned Up" - pedmec, March 21, 2025: "My guess is they damaged, misaligned, or just for forgot to put the gasket between the mixed air/gas tube and the burner door. … Damaging or forgetting the gasket is what I've seen techs do. we service a lot of Lochinvar's. lots of PM contracts." forum.heatinghelp.com, read October 1, 2026.
66. Heating Help: The Wall (forum.heatinghelp.com), "Dirty HX" - Paul Pollets, March 5, 2019: "The heat exchanger needs to be cleaned yearly or the HX is likely to have premature failure. Having the Viessmann cleaning tool is required." forum.heatinghelp.com, read October 1, 2026.
67. Heating Help: The Wall (forum.heatinghelp.com), "What's involved in a comprehensive annual service of a mod con boiler?" - GGross, August 24, 2023: "check the expansion tank (make sure it is correctly charged and functional) … combustion analysis before and after service … open the burner compartment clean the heat exchanger (this can be the bulk of time spent) … clean the condensate trap-refill trap … I do not see many techs actually do a solid service on mod-cons." forum.heatinghelp.com, read October 1, 2026.
68. Xylem McDonnell & Miller, Series 67 Installation & Maintenance Instructions MM-246752 Rev 12 and Series 150S/157S MM-210341 Rev 17 - Series 67: "Blow down weekly (at least once) when the boiler is in operation," "Disassemble and inspect annually," "Replace the control every 10 years"; Series 150S: "Replace head mechanism every 5 years." Series 67; Series 150S, read October 1, 2026.
69. Hydrolevel, Safgard 1100 instructions (061721), CycleGard CG450 instructions (012422) and VXT-24 instructions (0321) - Safgard 1100: "Check control operation annually by pressing the TEST button," "Remove the low water cut-off every five years and clean all surfaces in contact with water"; CG450: "remove and inspect the probe annually," drain test "The boiler will shut down within 15 seconds"; VXT: record and reset the feed counter and "Remove and clean the strainer" annually, "Replace the VXT Series Water Feeder after 12 years of service." Safgard 1100; CG450; VXT-24, read October 1, 2026.
70. U.S. Boiler Company (Burnham), MPO-IQ Installation & Service Manual 103859-16 (8/24) and MegaSteam Installation & Service Manual 103536-14 (10/25) - MPO-IQ: "adjust air for minimum smoke (not to exceed #1)," "CO2 of 11.5 to 13.0%," breech "A negative pressure reading up to -.03 inches water column is acceptable," Beckett AFG pump pressure 180 psi (Table 14-1) with positive overfire pressure; MegaSteam: Pressuretrol cut-out "(1) PSI and differential pressure (DIFF.) for .5 PSI." MPO-IQ; MegaSteam, read October 1, 2026.
71. Honeywell, L404F PressureTrol operating instructions, 71-2429-08 (Edition 05.23) - "A steam trap must be connected between the L404F and the boiler." Honeywell document library, read October 1, 2026.
72. Heating Help: The Wall (forum.heatinghelp.com), "When to let water out of boiler drain. Burnham Gas Steam" - EdTheHeaterMan, February 27, 2026: "Unless you have one of the float type LWCO controls that instruction is not for you. Most new boilers are equipped with a probe type electronic LWCO control. They only require annual maintenance." forum.heatinghelp.com, read October 1, 2026.
73. Heating Help: The Wall (forum.heatinghelp.com), "Steam Low Water Cut Off Maintenance" - RayWohlfarth, May 7, 2019: "The low water cutoff is the leading mechanical cause of boiler accidents and it should be tested regularly, opened and cleaned yearly, and I like to do the slow drain test which more closely simulates actual operating conditions." forum.heatinghelp.com, read October 1, 2026.
74. Minnesota Department of Labor and Industry, "Your guide to safer boiler operation" - "Low-water cutoff, evaporation test (steam boiler) – While the boiler is in operation, shut off the feedwater pump and monitor the boiler water-level. The low-water cutoff should shut down the burner before the water level goes out of sight low." dli.mn.gov, read October 1, 2026.
75. Riello, 40 F3/F5 burner instructions for Weil-McLain GO boilers (Riello 2903223, hosted by Weil-McLain) - pump pressure 140 to 160 psig on WGO boilers; "The filter should be replaced at least once a year"; electrode gap 5/32 in, 13/64 in above the nozzle centerline. weil-mclain.com, read October 1, 2026.
76. Weil-McLain, WGO Series 4 Boiler Manual 550-142-331/0225 and the Beckett AFG burner manual for WGO boilers, 550-143-079/1224 - annual list including "change nozzle," "check ignition electrode settings," "clean or change fuel filter and strainer," "Clean boiler flue ways"; "Burner should be adjusted to 13% CO2 or less with a smoke level of zero and over-fire of -0.01” to -0.02”"; "Normal cold water fill pressure for residential systems is 12 psig. Boiler water pH 7.0 to 8.5 is recommended"; Beckett pump pressure 150 to 175 psig by model. WGO manual; Beckett manual for WGO, read October 1, 2026.
77. PB Heat (Peerless), EC/ECT oil boiler IOM EC8000 R38 (06/25) - "Adjust burner and barometric draft control for highest CO² (Maximum 13.1% [EC(T)-e-03 - EC(T)-e-05] or maximum of 13% [EC(T)-e-06]) while maintaining a 0 Smoke and a minimum of -.01” W.C. draft overfire"; venting: "This draft is necessary to provide the required draft over fire of -.01” W.C. to -.02” W.C."; Beckett settings table "(140 psig Pump Pressure)." peerlessboilers.com, read October 1, 2026.
78. r/hvacadvice, "Keep having to reset oil burner" - Excellent_Wonder5982, November 14, 2024: "An oil fired boiler maintenance usually takes me over two hours to do it right." reddit.com, read October 1, 2026.
79. Colorado Division of Oil and Public Safety, "What the Inspector Looks for When Inspecting a Boiler" - "The first thing the inspector looks for is the boiler nameplate"; the relief or safety valve "is the most important device on a boiler"; controls including "the high temperature limit switch with a manual reset"; an emergency shut off switch "installed either right outside or right inside the boiler room door"; combustion air, flue pipe connections, expansion tanks; "Boiler rooms are not for storage of any items, and flammable items are not allowed under any circumstances"; "New gaskets should always be used after inspection." ops.colorado.gov, read October 1, 2026.
80. Missouri Division of Fire Safety, "Checklist for Starting Boilers After a Lay-Up Period" - "Drain and flush the boiler, open all handholes and mainholes"; "Install new gaskets, replace all handhole and manhole covers, refill boiler"; "Have the technician disassemble the low-water cutoff and water-feeding devices, then clean, recondition, and reassemble them." dfs.dps.mo.gov, read October 1, 2026.
81. National Board, "Top Ten Boiler and Combustion Safety Issues to Avoid" (BULLETIN, Summer 2010) - "In 26 states ASME CSD-1 … is an adopted code"; "In most states these laws call for inspection of water-side systems (water level controls and pressure-retaining devices), but not testing of fuel train safety devices." nationalboard.org, read October 1, 2026.
82. Heating Help: The Wall (forum.heatinghelp.com), "Insurance Inspector Strikes Again--Change relief valve" - JUGHNE, January 5, 2022: "Insurance inspector checks boilers once a year. This guy will spend 5 minutes per boiler. The only thing he actually does is lift the pressure relief valve handle. … I believe the inspection program is a good idea. It gives the service person a heads up and also makes the owner realize that maintenance is needed on all boilers. But if flame sensor or such fails tomorrow, the owner will say "but it was just inspected"." forum.heatinghelp.com, read October 1, 2026.
83. Heating Help: The Wall (forum.heatinghelp.com), "Are service contracts worth it?" - EBEBRATT-Ed, December 4, 2022: "Ask them a bunch of questions: Do they include cleaning the heating surfaces of the boiler? Do they clean the burners? do they check the chimney flue and smoke pipe? do they do a complete combustion test with printed results? Do they check operation of all safety and operating controls?" forum.heatinghelp.com, read October 1, 2026.
84. Heating Help: The Wall (forum.heatinghelp.com), "Maintenance Plan for New EK System" - EdTheHeaterMan, September 9, 2024: "At that point I started the Silver Gold and Platinum plans. Silver was maintenance only, Gold was 20% discounted parts and labor with no service call fee … I would take 100 random customers, and found that 80% of those customers never needed service calls after the maintenance was completed." forum.heatinghelp.com, read October 1, 2026.