Water heater maintenance checklist: the annual visit for tank, tankless and heat pump water heaters (free Google Docs, Word and PDF)

Published October 1, 2026

• The checklist is free. There is no signup and no email form; the links below go straight to the file.
• Deepsel is our product. It tracks the maintenance agreements that this visit belongs to, and the last section of the page describes it.
• The checklist does not replace the manual for the heater in front of you, its rating plate or the local code. Gas, venting and electrical items are for licensed technicians. Where a printed target and the manual disagree, the manual wins.

A water heater maintenance checklist is the list a plumber or service technician works through on a maintenance visit to a storage tank, tankless or heat pump water heater, with each reading written next to a target. Every heater gets the water pressure, expansion tank, relief valve and delivered temperature checks. A gas tank adds the burner, venting and gas readings, an electric tank adds the element readings, and every tank gets the flush and the anode rod. The tankless water heater maintenance checklist is a section of its own, covering descaling, filters, condensate and gas pressure. The targets come from the A. O. Smith, Bradford White, Rheem, Rinnai, Navien and Noritz manuals and from the 2021 International Plumbing Code and International Fuel Gas Code, and where the manufacturers disagree the checklist prints each of their figures.

There are three ways to get it: make your own copy in Google Docs (one click puts it in 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 six pages. Pages 1 and 2 hold the job record and section A, which every heater gets. Sections B to E follow, for gas tanks, electric tanks, the flush and anode rod, and heat pump water heaters. Section F, the tankless section, starts on its own page, and section G is the findings and sign-off. A tankless job needs pages 1, 2, 5 and 6. A heating boiler has its own sheet, the boiler maintenance checklist, and every free checklist in the set is listed on the checklists page.

We read the pages that rank for this search before writing this checklist. ServiceChannel's four-page PDF is free and needs no form, but it is a list of checkboxes with a notes column. No task has a target or a place to write a reading, and the annual list says to replace the anode rod every year.¹ A. O. Smith's one-page training sheet prints numbers (50 to 60 psi at the pressure-reducing valve, 80 psi as the code maximum, an anode check at least every three years), but it covers tank heaters only.² Lowe's says to service the relief valve once a year and flush the tank each time, and it gives tankless units one answer in its FAQ.³ mitti's five-step checklist has no tankless section.⁴ Navien's own maintenance page says annual service is recommended and prints no value to check against.⁵ On the Reddit thread that comes up for the tankless search, owners gave three different answers on how often to flush: once a year, every couple of years and every few months.⁶ None of these pages gives the descaling time, the water hardness that sets the descaling interval, the gas pressure window or the CO limit in the vent. The manuals and the fuel gas code give all four, and the manuals do not all agree.

How often does a water heater need maintenance?

The manuals agree on a minimum of one inspection a year, and Bradford White and Rinnai specify a qualified technician. Bradford White's manual says: "The water heater should be inspected at a minimum annually by a qualified service technician for damaged components and/or joints not sealed."⁷ Rinnai's tankless manual says the heater "must be inspected annually by a trained and qualified professional."⁸ For the individual tasks, the intervals differ. The table gives the tank-heater intervals from the manuals and manufacturer guides listed in the sources.

The checklist does not choose one of these schedules. It records what the visit found (how much sediment came out, how much core wire the anode shows, whether the valve reseated), and the next date is set from that record. Plumbers on r/Plumbing disagree about the anode interval in the same way. In August 2026 a commenter wrote: "Most anode rods should be change every 4-5 years. The book says to 'inspect' them. But the labor to do that inspection costs a lot more than the part. So, just 'replace' them." Another replied that a first change at twelve years "can do more damage than good at that age."¹⁶ In a 2023 thread, a third commenter said that "a decent chunk" of the rods they had replaced were passivated: "Whole rod still there, but not doing a damn thing."¹⁷ A measurement written down each year shows which of these views applies to a given house.

Section A: the checks every water heater gets

Section A applies to every heater, tank or tankless, and is completed before the fuel-specific sections. Most of its rows are on the water side, and most of the targets come from the plumbing code.

The pressure and expansion rows come before the relief valve row because high pressure and thermal expansion are the two causes A. O. Smith gives for a dripping valve, which "will drip if the water pressure is too high or due to thermal expansion on a closed plumbing system." Its training sheet gives the order of repair: "Control water pressure and install a thermal expansion tank before replacing a dripping T&P relief valve."² A new valve in a house at 85 psi with a waterlogged expansion tank will keep dripping. The checklist records the static pressure on one row and the expansion tank precharge and supply pressure on the next, so the cause is in writing when the customer asks why a new valve is not the repair.

The relief valve row also has a space for a date. Watts, which makes the valve, says the lever must be operated at least once a year and that the valve should be "inspected and replaced, if necessary, AT LEAST ONCE EVERY TWO TO FOUR YEARS," because corrosion inside the valve "can only be detected if the valve and its components are physically removed and inspected."¹⁴ Amtrol's expansion tank instructions call for that inspection at least every three years,¹⁵ and A. O. Smith's web guide calls for it every five.¹⁰ The date stamped on the valve is written on the checklist so that the next visit knows when the inspection is due. The relief valve on a heating boiler has its own row and test intervals on the boiler maintenance checklist.

Section B: gas tank water heaters

The CO limit is where this section differs from a furnace checklist. IFGC Appendix D, the fuel gas code's recommended procedure for a safety inspection of an existing gas appliance, sets the vent limit at 400 ppm air-free for a central furnace and at 200 for a water heater.²⁰ A technician who applies the furnace limit to a water heater would pass a reading between 200 and 400 ppm, which Appendix D fails. The furnace maintenance checklist prints the furnace tiers, and this checklist prints 200.

The combustion analyzer and manometer used for the CO and gas pressure rows are on the HVAC technician tool list, which separates the tools a technician buys from the tools the shop supplies. When a furnace replacement leaves the water heater as the only appliance on the old chimney, the vent check for that case is a row on the HVAC installation checklist.

Section C: electric tank water heaters

Section D: draining, flushing and the anode rod

Section D covers the flush and the anode rod, the two tasks on which the manuals disagree most. A. O. Smith's manual says to drain and flush the tank every six months.⁹ Bradford White says to drain a gallon every month, and its electric manual adds "until the water runs clear."⁷¹¹ Rheem says a few quarts every month, and its 2025 guide recommends a flush "about every six months" in hard-water areas.¹²¹³ A. O. Smith's training sheet asks for the least: drain 2 to 3 gallons a year, and "If water is milky, drain entire tank."² The checklist records the gallons drained and the appearance of the water, and that record is the basis for shortening or lengthening the interval at that house.

The anode rod has a measurable replacement point. Rheem and A. O. Smith each print one, and Bradford White leaves the decision to the technician.

The checklist asks for the inches of core wire showing and the thinnest diameter of the rod. With those two figures, the decision to replace or keep the rod rests on a measurement, and next year's visit can see how fast the rod is being consumed. Rheem's guide also gives the remedy for a rotten-egg odor in the hot water: "switching to an aluminum anode or powered anode."¹³

The first flush of an old tank with no service record is the customer's decision, and it is made before the hose is connected. A December 2025 r/Plumbing thread titled "Don't be like me. Flush your water heater." began with a 30-year-old heater whose sediment "was above the lower element and wouldn't drain from the valve." The replies disagreed about what to do with a tank in that condition. One commenter wrote: "If you moved in and don't have service history it's better to not touch it." Another wrote: "In two separate houses I flushed the water heaters that were already in there when I bought them. Both failed within a month of doing so."²⁴ In a 2023 thread about an 18-year-old tank, a commenter wrote: "Sometimes messing around with 18 year old water heaters is how you get to buy a new one, today."¹⁷ For that reason the first row of section A is the service history. A tank with no history gets the risk explained (a drain valve that may not reseal, sediment that may be sealing a weak spot), and the customer's decision is written down. The plumbing maintenance agreement template has the matching contract clause for older water heaters and their drain valves.

Section E: heat pump water heaters

A heat pump (hybrid) water heater is a tank with a heat pump module on top, so it gets sections A, C and D and three more rows: the air filter, the condensate drain, and the operating mode and fault codes. ENERGY STAR's page on heat pump water heaters notes that they "may also require annual maintenance, including changing air filters."²⁵ The Rheem and Bradford White manuals both tie the filter cleaning to the unit's own alert. Rheem says to clean the filter "when 'Clean filter reminder' alert appears," with mild detergent and water, and Bradford White's unit shows a fault code when its filter needs cleaning.²⁶²⁷ Bradford White states the consequence of a dirty filter: "If the filter gets too dirty, the unit will automatically switch to Electric (Only) Mode and energy savings will be lost."²⁷ For the condensate line, Rheem's instruction is: "At least once a year pour a cup of bleach in the access opening of the condensate drain to kill any algae, mold, or mildew that has formed in the pipe."²⁶ Bradford White's yearly list also includes draining and flushing the tank once a year and inspecting the elements and wiring.²⁷

Section F: the tankless water heater maintenance checklist

A tankless water heater has no anode rod and no tank to drain. Its maintenance items are a heat exchanger that scales, an inlet screen that catches debris, an air intake filter on the Navien and Rinnai condensing models, and a condensate trap and neutralizer on condensing units. Descaling is the main task of the visit, and the four manuals give four different procedures for it.

Rinnai and Navien set the flushing interval by water hardness, using the same bands, and both base their water quality limits on the EPA's secondary drinking water standards.⁸²⁹ Rheem's chart prints the same 200 mg/L hardness ceiling.³⁰ Navien's footnote adds that flushing "is recommended if a treatment device is not installed."²⁹ The checklist asks for the hardness and the treatment near the top of the tankless page, because the two together decide whether a descale is due at all.

The warranty terms are the reason a dated record matters. Rinnai's manual says: "Damage caused by lime/scale build-up is not covered by the water heater's warranty."⁸ Navien's manual says: "Damage caused by poor water quality is not covered under warranty."²⁹ Noritz excludes "Water in excess of 12 gpg (200mg/L) of hardness."³¹ Rheem's limited warranty does not cover failures caused by water outside the limits in its chart.³⁰ A dated checklist with the hardness and each descale written on it is the owner's record if one of those exclusions is raised.

The table below lists the other tankless checks and their targets.

A tankless unit that has gone years without a descale carries the same kind of first-visit risk as a neglected tank. In a September 2026 thread about a Rheem unit with no descale in four years, one commenter reported having cleaned "a few that were not properly maintained and they did start leaking, but only a few out of many." Another described a former employer's rule: "if it had been 4 or more years since a descale we made the customer sign a liability waiver saying we weren't responsible for any issues after descaling."³² The checklist does not include a waiver. Its nearest equivalent is the first row of section A, which records the service history and the customer's decision before the pump is connected. The piping can be a second obstacle, because the descale is done through the service valves. "Not all tankless have service valves," a commenter wrote in 2024, after having "Seen far too many installed by Handy Andys, HVAC techs, apprentices and homeowners that don't have service valves."³³

Water heater temperature setting: 120°F at the tap, and the Legionella guidance

For a house, the target is 120°F at the tap. CPSC guidance, the Department of Energy's home checklist and the IFGC's inspection procedure all use that number, and the checklist has the technician measure it at the nearest tub or sink instead of reading it off the dial.²¹³⁴²⁰ The dial alone is not a reliable guide. A. O. Smith's manual warns that "short repeated heating cycles caused by small hot water uses can cause temperatures at the point of use to exceed the thermostat setting by up to 30°F."⁹ Legionella guidance calls for hotter storage, and the sources do not agree on a single number.

The scald data is the reason 120°F at the tap remains the target unless a mixing valve is fitted. CPSC says: "Most adults will suffer third-degree burns if exposed to 150 degree water for two seconds. Burns will also occur with a six-second exposure to 140 degree water or with a thirty second exposure to 130 degree water."²¹ A heater that stores water at 140°F for Legionella control needs a thermostatic mixing valve between it and the fixtures, and the checklist has a box for that valve.

The water heater visit belongs in the maintenance agreement

Every manufacturer quoted on this page asks for at least one inspection a year, and a September 2026 r/Plumbing thread suggests that many owners do not know it. In that thread, a homeowner in Northern Virginia asked whether anyone would descale a two-year-old tankless unit. A commenter in Southern California, who said most newer heaters there are tankless, wrote: "I have yet to talk with anyone who has flushed their tankless." Some of the plumbers in the thread do not offer the work unless asked. One of them wrote: "I charge the same rate as a service call plus the flushing agents price. A lot of people seem offended by the price so I never mention it as something we offer." Another wrote: "Yes, I do it. It's easy money. No, I don't advertise that i do it."³⁷ Navien's maintenance page warns that failing to perform the maintenance in the manual "may void the manufacturer's limited warranty."⁵

A maintenance agreement closes that gap. The customer pays for a yearly visit with a written scope (the flush or descale, the relief valve, the anode and the gas readings), the shop books the visit without waiting to be asked, and this checklist is the record of what was done. The plumbing maintenance agreement template lists each water heater by serial number and install year, prices a tankless unit separately and includes the clause for older water heaters. The readings from this checklist belong in the equipment maintenance log, filed by heater, so that next year's technician can compare the anode, the hardness and the gas pressure against this year's figures.

Whether that promise is kept depends on the office. A shop with 200 plans has at least 200 heaters due across the year, some of them on a six-month descale because the water is hard. A visit that never gets booked is a visit the customer paid for and did not receive. The free maintenance agreement tracking spreadsheet is the place to start. It has one row per agreement, with the equipment covered, the visits owed and delivered with dates, and the renewal date. The guide on how to track HVAC maintenance agreements explains each column, and the preventive maintenance schedule template lays the due dates out on a 12-month grid.

Above about 80 to 100 agreements, the constraint is the hours the office has in a week and no longer the spreadsheet. Deepsel, our product, does that office work for plumbing, HVAC and electrical shops. It keeps the ledger of visits owed versus delivered for each covered unit, 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 technician still fills in this checklist at the heater, and Deepsel holds the record that the visit was owed, booked and delivered.

Frequently asked questions

What should a water heater maintenance checklist include?

Every heater gets the static water pressure (a pressure-reducing valve is required above 80 psi), the expansion tank precharge, the relief valve lever and discharge pipe, the drain pan and the delivered temperature at the nearest tub or sink. A gas tank adds a gas leak check, inlet gas pressure, the burner and pilot flame, burner cleaning, the thermocouple or thermopile, a spillage test at the draft hood after five minutes and CO in the vent, where IFGC Appendix D sets 200 ppm air-free as the limit. An electric tank adds element resistance (12.8 ohms within 6 percent for a 4,500 watt element at 240 volts), a ground test and amps. Every tank gets the drain and flush and a measured anode rod. A tankless unit gets the water hardness, the descale, the inlet and air filters, the condensate neutralizer, the burner flame, inlet gas pressure and the vent. Each reading goes next to a printed target.

How often should a water heater be flushed?

The manufacturers disagree. A. O. Smith's manual says to drain and flush the tank every six months. Bradford White says to drain a gallon every month, and Rheem says a few quarts every month, with a full flush about every six months in hard water. A. O. Smith's training sheet says to drain 2 to 3 gallons a year, and the whole tank only if the water comes out milky. All three agree on at least a yearly inspection. Record how much sediment comes out at each visit and set the next date from that record. Before a tank that has never been flushed is drained, the customer should have the risk explained.

How often should a tankless water heater be descaled?

The interval depends on water hardness. Rinnai and Navien print the same bands. Water under 4 grains per gallon (60 mg/L) needs no flushing. From 4 to 12 grains, Rinnai says to flush once a year in a home and twice a year in a commercial building, and Navien recommends the flush wherever no treatment device is installed. Above 12 grains (200 mg/L), both require water treatment. Rheem says annually or as a professional recommends, and Noritz says annually where hard water is untreated. The descale is white vinegar or a descaling solution pumped through the heat exchanger for 45 minutes to an hour, followed by a rinse of 3 to 5 minutes and a cleaned inlet filter.

Should you flush an old water heater that has never been flushed?

Flush it only after the customer has heard the risk and agreed. On r/Plumbing, commenters describe tanks that failed within a month of a first flush and sediment that would not drain from the valve, and one commenter's former employer required a signed waiver before descaling a tankless unit that had gone four or more years without one. The first row of section A on the checklist records the service history and the customer's decision before anything is drained.

How often should the anode rod be checked?

Bradford White says every two years. Rheem and A. O. Smith's web guide say every year. A. O. Smith's manual says no later than year three and every year after that. A. O. Smith and Bradford White both say to check more often with softened water. Replace the rod when more than 6 inches of core wire shows at either end (Rheem), or when most of the rod is under 3/8 inch thick or about a third of its length shows wire (A. O. Smith). Write down the inches of wire and the diameter so the next visit can see how fast the rod is being consumed.

What temperature should a water heater be set to?

For a home, set it so the water is 120 degrees F at the tap. CPSC urges that setting, the Department of Energy's home checklist uses it, and IFGC Appendix D has the inspector measure the water at the nearest tub or sink to confirm it is no higher than 120. Legionella guidance from the CDC's building water management toolkit and from OSHA calls for storing hot water at or above 140 degrees F, and the CDC says a heater set above 120 needs thermostatic mixing valves at the faucets or showers. Measure the temperature at the tap and do not rely on the dial, because A. O. Smith notes that short repeated heating cycles can push the delivered temperature up to 30 degrees above the setting.

Sources

1. ServiceChannel, "Hot Water Heater Preventative Maintenance Checklist" and the linked four-page PDF checklist - daily, monthly and annual checkbox lists with a notes column and no target values or reading fields; no tankless section; the annual list includes "Replace the anode rod"; the blog gives the relief valve opening points as 210°F and 150 psi and says bathing water "shouldn't exceed 120 degrees Fahrenheit." servicechannel.com; PDF, published January 23, 2024, updated August 11, 2024, read October 1, 2026.
2. A. O. Smith University, "Annual Water Heater Maintenance Checklist" (one-page training handout, tank heaters only) - "Drain 2-3 gallons of water. If water is milky, drain entire tank."; "T&P relief valves will drip if the water pressure is too high or due to thermal expansion on a closed plumbing system"; "Control water pressure and install a thermal expansion tank before replacing a dripping T&P relief valve."; "Most experts recommend setting the Pressure Reducing Valve to 50-60 psi to protect appliances."; "If water pressure is above code maximum (80 psi), install a Pressure Reducing Valve (PRV)."; "If daytime water pressure is 60 psi or higher, nighttime pressure will likely be above 80 psi"; expansion tank "Air pressure should match water pressure."; "Check the anode rod at least every three years depending on local water conditions. Units with a water softener should be checked annually."; "Remove anode rod with 1 1/16” socket and impact wrench." university.hotwater.com, posted July 2015, read October 1, 2026.
3. Lowe's, "Maintain a Water Heater" (Valerie Albarda) - "Maintenance should be performed on the T&P valve once a year and should be inspected by a professional every 5 years"; flush "each time you check the pressure relief valve"; tankless units get one FAQ answer: "these appliances need flushing and inspection." lowes.com, updated December 6, 2023, read October 1, 2026.
4. mitti (by SafetyCulture), "Water Heater Maintenance Checklists" - a five-step checklist with no tankless section; water pressure "(40-60 psi in the daytime)"; "an anode rod may need to be replaced every 3-5 years." mitti.com, updated July 21, 2026, read October 1, 2026.
5. Navien, "Tankless Water Heater Maintenance" - lists filter cleaning, the condensate trap and flushing with no target values; "annual maintenance is recommended"; "failure to perform regular maintenance as set forth in the user manual may void the manufacturer's limited warranty." navieninc.com, published November 26, 2024, updated March 16, 2026, read October 1, 2026.
6. r/homeowners, "Tankless hot water heater maintenance?" - replies include "You should flush it once a year," "Flush with vinegar solution every couple years" and "Just flush it every few months." reddit.com, January 25, 2022, read October 1, 2026.
7. Bradford White, "Installation and Operation Manual: Gas-Fired Water Heater," 238-51007-00R, Rev 07/26 - "The water heater should be inspected at a minimum annually by a qualified service technician for damaged components and/or joints not sealed"; "Annually check the operation of the thermostat"; flames checked "at periodic intervals (not more than 6 months)," air shutter turned "until the yellow tips disappear, and the flame becomes blue," "Too much air will cause the flame to lift off the burner ports ... Too little air will result in soot formation"; "Annually remove the inner door and main burner assembly to clean orifices"; relief valve "At least once a year ... Lift the lever at the top of the valve several times until the valve seats properly without leaking and operates freely"; "Monthly drain off a gallon of water to remove silt and sediment"; "The anode rod should be inspected periodically (every 2 years)," more often with "softened (or phosphate treated) water"; vent hood screen cleaned; spillage checked at the draft hood; "Check for gas leaks with a soap and water solution ... NEVER USE A MATCH OR OPEN FLAME FOR TESTING!"; minimum gas supply pressure "1 in (0.25 kPa) water column above the operating manifold pressure," maximum "14 in (3.5 kPa) water column"; drain pan "at least 4 in (10.2 cm) greater than the diameter of the water heater," piped at least 3/4 in; garage burners and igniters "not less than 18 in (45.7 cm) above the floor"; ICON control charts: two flashes and a pause means low thermopile voltage. docs.bradfordwhite.com, read October 1, 2026.
8. Rinnai, "Tankless Water Heater Installation and Operation Manual," SENSEI RX residential, 100000839 - "This water heater must be inspected annually by a trained and qualified professional"; Table 3, "Recommended Water Treatment," by hardness (0-60 mg/L, 0-4 grains per gallon: none; 61-120 and 121-160 mg/L, 4-7 and 7-9 grains: "Water Softener or Rinnai Scale Cutter is Recommended"; 161-200 mg/L, 9-12 grains: "Water Softener or Rinnai Scale Cutter is Strongly Recommended"; 200+ mg/L, 12+ grains: "Water Softener or Rinnai Scale Cutter is Required"; flushing for every band above soft "Residential: Once/Year" and "Commercial: Twice/Year"); Table 4, "Water Quality Guidelines" ("Total Hardness Up to 200 mg/L"; chlorides up to 250 mg/L, pH 6.5 to 8.5 and TDS up to 500 mg/L marked "*Source: Part 143 National Secondary Drinking Water Regulation"); "Pour four gallons of undiluted virgin, food grade, white vinegar into pail"; "at least 1 hour at a rate of four gallons per minute"; rinse "for five minutes," then clean the inlet filter; "An LC diagnostic code also indicates the unit is beginning to lime/scale up and must be flushed"; "Damage caused by lime/scale build-up is not covered by the water heater's warranty"; "Rinnai strongly recommends installation of isolation valves"; "The flame must burn with a clear, blue, stable flame"; vacuum "the main burner and fan blades"; "periodically inspect the air filter," clean it "If the air filter appears to have lint and/or dust build up," and "DO NOT operate this water heater if the air filter is not in place"; "Ensure condensate is flowing and the end of the drain is open to the atmosphere"; "Operate the pressure relief valve manually once a year"; "The last nine maintenance codes display"; inlet gas pressure not below "5.0” w.c. (1.2 kPa) for natural gas, 8.0” w.c. (2.0 kPa) for LP gas while all gas appliances operate at the maximum input rate"; freeze protection to -22°F indoors and -4°F outdoors "When connected to a 120-volt power supply." media.rinnai.us, March 2025, read October 1, 2026.
9. A. O. Smith, "Instruction Manual: Residential Gas Water Heaters," 315628-002 - "It is recommended that the tank be drained and flushed every 6 months"; "The anode rod should be inspected after a maximum of three years and annually thereafter"; "Artificially softened water requires the anode rod to be inspected annually"; depleted when "The majority of the rods diameter is less than 3/8”" or support wire shows along "approx. 1/3 or more of the anode rod's length"; "The temperature-pressure relief valve must be manually operated at least once a year"; venting and burner each visually inspected "At least once a year"; "Soot build-up indicates a problem that requires correction before further use"; "Vent pipes must be secured at each joint with sheet metal screws"; "The inlet gas pressure must not exceed 14 inch water column"; drain pan "at least 2” (51 mm) greater than the water heater dimensions"; "Short repeated heating cycles caused by small hot water uses can cause temperatures at the point of use to exceed the thermostat setting by up to 30°F"; the approximately 120°F mark "is preferred starting point." assets.aosmith.com, printed March 2015, read October 1, 2026.
10. A. O. Smith, "Water Heater Maintenance Guide" - the T&P valve inspected once a year by the owner "and every 5 years by a professional"; "we recommend inspecting the anode rod once a year"; "use a 1 1/16 deep well socket to remove the anode"; a good rod "should be smooth and around a half inch in diameter"; replace with "several inches of exposed core wire." hotwater.com, read October 1, 2026.
11. Bradford White, "Installation and Operation Manual: Electric Water Heater," 238-44422-00AB, Rev 08/26 - "drain the water heater at least once a month through the drain valve until the water runs clear"; "Annually, check the operation of the thermostat(s)"; "Bi-annually, check the seal around the heating elements for leaks"; relief valve checked "At least once a year"; anode "inspected periodically (every 2 years)"; "Failure of the element(s) due to dry-firing is not covered by warranty"; thermostats preset to "approximately 120°F (49°C) to reduce the risk of scald injury." docs.bradfordwhite.com, read October 1, 2026.
12. Rheem, "Use & Care Manual: Residential Gas - Low NOx Emissions Water Heaters," AP23698 - "At least once a year, lift and release the lever handle on the temperature pressure relief valve"; "a few quarts of water be drained from the water heater's tank every month"; "The anode rod should be removed from the water heater's tank annually for inspection and replaced when more than 6 in of core wire is exposed at either end of the rod"; "Test for spillage at the draft hood relief opening after 5 minutes of burner operation. Use a flame of a match or candle or smoke"; "Visually inspect the pilot burner and main burner annually"; if the inner door is removed "the inner door gaskets, burner access door gasket, and transition pan gasket must be replaced"; inlet gas pressure "must not exceed 10.5 in w.c. for natural gas"; vent inspected "at least annually." files.myrheem.com, July 2023, read October 1, 2026.
13. Rheem, "How to Keep Your Tank and Tankless Water Heaters Running at Peak Performance" - "In hard-water areas, plan to flush or descale about every six months"; anode: "Checking it annually can add years to your water heater's lifespan"; rotten-egg odor "can be solved by switching to an aluminum anode or powered anode"; tankless tasks "at least once a year." rheem.com, December 22, 2025, read October 1, 2026.
14. Watts, Tag 100, temperature and pressure relief valve instructions - "the valve lever MUST be operated AT LEAST ONCE A YEAR"; "If water does not flow freely when the lever is operated, replacement of the valve is required"; valves "should be inspected and replaced, if necessary, AT LEAST ONCE EVERY TWO TO FOUR YEARS depending on local water conditions"; corrosion "can only be detected if the valve and its components are physically removed and inspected." watts.com, read October 1, 2026.
15. Amtrol, "Thermal Expansion Tanks for Potable Water: Installation & Operation Instructions," models ST-5 through ST-210V, 9015-942 (04/23) - "With tank empty of water, adjust air precharge to match cold water supply pressure"; "A licensed professional should check the complete system, including the expansion tank, yearly"; "Always check the precharge while the tank is isolated and empty of water"; "At least once every 3 years or if discharge is present, a licensed professional should inspect the temperature and pressure relief valve." amtrol.com, April 2023, read October 1, 2026.
16. r/Plumbing, "Anode rod...suggested replacement cycle" - "Most anode rods should be change every 4-5 years. The book says to 'inspect' them. But the labor to do that inspection costs a lot more than the part. So, just 'replace' them"; "You don't normally want to change an anode for the first time after 12 years ... It can do more damage than good at that age." reddit.com, August 16, 2026, read October 1, 2026.
17. r/Plumbing, "Got the Anode Rod out of a 2005 water heater, AMA" - "a decent chunk of those that I have replaced had ended up passivated. Whole rod still there, but not doing a damn thing"; "Sometimes messing around with 18 year old water heaters is how you get to buy a new one, today." reddit.com, November 9, 2023, read October 1, 2026.
18. 2021 International Plumbing Code, Chapter 6, Water Supply and Distribution - 604.8 (a pressure-reducing valve "Where water pressure within a building exceeds 80 psi (552 kPa) static"); 607.3 (a thermal expansion control device where cold water "passes through a check valve, pressure reducing valve or backflow preventer," connected "downstream of all check valves, pressure reducing valves and backflow preventers"). codes.iccsafe.org, read October 1, 2026.
19. 2021 International Plumbing Code, Chapter 5, Water Heaters - 501.6 (water from tankless heaters "not greater than 140°F (60°C) where intended for domestic uses"); 502.5 (a level working space of 30 by 30 inches at the control side); 504.4 ("The relief valve shall not be used as a means of controlling thermal expansion"); 504.6 (discharge piping requirements 1 to 14, including "Not be trapped," termination "not more than 6 inches (152 mm) above" the floor or receptor, "Not have a threaded connection at the end"); 504.7 and 504.7.1 (pan where leakage would cause damage, "not less than 1 1/2 inches (38 mm) in depth," a drain "not less than 3/4 inch," no plastic pan under a gas-fired heater). codes.iccsafe.org, read October 1, 2026.
20. 2021 International Fuel Gas Code, Appendix D, "Recommended Procedure for Safety Inspection of an Existing Appliance Installation," Section D106 - water heaters: relief valve in operating condition; FVIR "inspection covers, glass, and gaskets are intact and in place"; "measure the water temperature at the closest tub or sink to verify that it is no greater than 120ºF"; straps "in two locations (high and low)" where local code requires; "Measure the CO in the vent after 5 minutes of main burner operation"; Table D106 limits: water heater "200 ppm air free," central furnace 400. codes.iccsafe.org, read October 1, 2026.
21. U.S. Consumer Product Safety Commission, Publication 5098, "Avoiding Tap Water Scalds" - CPSC "urges all users to lower their water heaters to 120 degrees Fahrenheit"; "Most adults will suffer third-degree burns if exposed to 150 degree water for two seconds. Burns will also occur with a six-second exposure to 140 degree water or with a thirty second exposure to 130 degree water"; "Most electric water heaters have two thermostats, both of which must be set to a common temperature for proper operation." cpsc.gov, read October 1, 2026.
22. Bradford White, "Flammable Vapor Ignition Resistant Water Heater Service Manual: Troubleshooting Guide," 44943 rev. C - closed-circuit thermocouple test: "If meter reads 10 millivolts or higher, the thermocouple is OK" (White-Rodgers control); "If meter reads 13 millivolts or higher, the thermocouple is OK" (Robertshaw control). docs.bradfordwhite.com, read October 1, 2026.
23. Bradford White, "Residential Electric Water Heaters Service Manual," 238-51544-00D, Rev 5/22 - "Reading should be 12.8 ohms (±6%) for a 240 volt, 4500 watt element"; ohms equal volts squared divided by watts; ground test: "Any reading indicates a grounded element and the element must be replaced"; "4500W/240V = 18.75A." docs.bradfordwhite.com, read October 1, 2026.
24. r/Plumbing, "Don't be like me. Flush your water heater." - the post: "Just replaced our 30 year old water heater, sediment was above the lower element and wouldn't drain from the valve"; replies: "If you moved in and don't have service history it's better to not touch it"; "In two separate houses I flushed the water heaters that were already in there when I bought them. Both failed within a month of doing so." reddit.com, December 4, 2025, read October 1, 2026.
25. ENERGY STAR, "Heat Pump Water Heaters" - "HPWHs may also require annual maintenance, including changing air filters." energystar.gov, read October 1, 2026.
26. Rheem, "Use & Care Manual: Electric Residential Hybrid Water Heater," AP23657 Rev 01 - "It is recommended to clean the filter on top of the heat pump when 'Clean filter reminder' alert appears. Clean by washing with mild detergent and water"; "At least once a year pour a cup of bleach in the access opening of the condensate drain to kill any algae, mold, or mildew that has formed in the pipe." media.rheem.com, July 2024, read October 1, 2026.
27. Bradford White, "Installation and Operation Manual: Hybrid Electric Heat Pump Water Heater," 238-55123-00C - yearly program: relief valve, elements and wiring, "drain and flush the water heater tank once a year," "Clean the air filter," "Clear the condensate drain pan and the drain lines," anode inspected regularly; "When the filter requires cleaning, a fault code will display"; "If the filter gets too dirty, the unit will automatically switch to Electric (Only) Mode and energy savings will be lost." docs.bradfordwhite.com, read October 1, 2026.
28. Navien, "NPE-2 User's Information Manual" - flushing: circulate the cleaning solution "for at least 45 minutes," rinse "for 5 minutes," then "Remove the cold water inlet filter from the water heater and clean out any residue"; "you should clean the air intake filter every 3-4 months," a clogged filter shows "Error Code 110"; "Inspect the vent termination and air intake supply annually," and discontinue use if any vent or intake pipe is "damaged in any way, separated at a joint, or show evidence of corrosion, rusting, or melting." navieninc.com, December 2020, read October 1, 2026.
29. Navien, "NPE-A2/S2 Installation Manual" (file dated January 27, 2026) - water quality table from the EPA secondary standards (hardness "Up to 200 mg/l (12 grains/gallon)"); treatment and flush frequency by hardness (0-4 grains none; 4-7 and 7-9 grains, a water softener or Navien PeakFlow "is Recommended"; 9-12 grains "is HIGHLY Recommended"; over 12 grains "is Required"; flush "Once/Year" at 4-7 grains, and "Residential: Once/Year" and "Commercial: Twice/Year" from 7 grains up), "Flushing is recommended if a treatment device is not installed," using "white vinegar or solutions that are specifically formulated for use on tankless water heaters"; "Damage caused by poor water quality is not covered under warranty"; "The inlet gas pressure must be maintained between 3.5 in. and 10.5 in. WC for natural gas and between 8.0 in. and 13 in. WC for liquefied propane"; condensate "has an acidic pH of 3 - 5"; "We recommend an annual pH test" of the neutralizer, replacing the media "when the pH is below 6.0" if no local level is set; error history menu. navieninc.com, read October 1, 2026.
30. Rheem, "Condensing Tankless Water Heater Use and Care Manual," AP22745 Rev 04 - "Check and clean the water filter monthly"; "Annually check the operation of the pressure relief valve"; flushing "should be conducted annually or as recommended by a professional"; "Pour no more than 2 gallons of virgin food grade white vinegar"; "allow to circulate vinegar for 45 minutes"; rinse "for 5 minutes"; "Recommend 120°F for the temperature setting when flushing procedure is completed"; water quality chart (hardness up to 200 mg/L, pH 6.5 to 8.5, TDS up to 500 mg/L, chlorides up to 250 mg/L) citing the National Secondary Drinking Water Regulations; "the limited warranty provided with the water heater does not cover defects, malfunctions or failures resulting from water conditions that are not in accordance with the specifications." media.rheem.com, January 2023, read October 1, 2026.
31. Noritz, Knowledge Base, "What maintenance is recommended?" and "Descale Procedure Group C," Rev. 06/16 - the inlet filter "should be checked for debris about once a year"; with hard water and no treatment "the unit will need to be flushed annually"; "Pour 1 gallon of 'Calcium, Lime and Rust Removal Product' and 1 gallon water into the bucket"; circulate "for 1 hour"; rinse "for 3 minutes or more"; not covered by warranty: "Water in excess of 12 gpg (200mg/L) of hardness." help.noritz.com; descale procedure, read October 1, 2026.
32. r/Plumbing, "Rheem tankless water heater has not been descaled for 4 years (maybe more?)" - "I have cleaned a few that were not properly maintained and they did start leaking, but only a few out of many"; "The last company I worked for if it had been 4 or more years since a descale we made the customer sign a liability waiver saying we weren't responsible for any issues after descaling." reddit.com, September 23, 2026, read October 1, 2026.
33. r/Plumbing, "Do tankless water heaters require annual maintenance from a plumber?" - "Not all tankless have service valves lol. Seen far too many installed by Handy Andys, HVAC techs, apprentices and homeowners that don't have service valves." reddit.com, January 22, 2024, read October 1, 2026.
34. U.S. Department of Energy, Federal Energy Management Program, "Home Energy Checklist" - "Turn down the temperature of your water heater to the warm setting (120°F)." energy.gov, read October 1, 2026.
35. Centers for Disease Control and Prevention, "Vacation Rental Owners and Managers" - "Set your property's water heater at or above 120°F to minimize the growth of Legionella"; "If the water heater is set above 120°F, use thermostatic mixing valves at the faucet or shower to avoid scalding." cdc.gov. And "Controlling Legionella in Potable Water Systems" (Legionella Control Toolkit) - "Store hot water above 140°F (60°C). Maintain circulating hot water above 120°F (49°C)." cdc.gov. Both read October 1, 2026.
36. Occupational Safety and Health Administration, "Legionellosis (Legionnaires' Disease and Pontiac Fever) - Control Prevention" - "Storing domestic hot water at a minimum of 60°C (140°F) and delivering hot water at a minimum of 50°C (122°F) to all outlets." osha.gov, read October 1, 2026.
37. r/Plumbing, "Question for plumbers about tankless service: do people who install tankless units have some idea about service them for basic maintenance like descaling?" - the post, from Northern Virginia, about a two-year-old Rheem unit; replies: "I have yet to talk with anyone who has flushed their tankless"; "I charge the same rate as a service call plus the flushing agents price. A lot of people seem offended by the price so I never mention it as something we offer"; "Yes, I do it. It's easy money. No, I don't advertise that i do it." reddit.com, September 18, 2026, read October 1, 2026.