Water heater maintenance

Maintenance on a storage tank is three jobs and a habit of looking. Flush sediment before it hardens into a noise and a slow recovery. Inspect the anode rod before the steel becomes the anode. Confirm the temperature-and-pressure relief valve is not capped, painted shut, or piped uphill. Everything else people add to a “complete checklist” is either a safety inspection, which belongs in the safety section, or a repair of something that has already failed.

Tankless maintenance is a descale, an inlet-screen cleaning if the manual shows one, and a look at the outdoor terminations for leaves, snow, and nests. Heat pump maintenance adds a filter and a condensate hose. Doing a tank flush on a tankless heater is not possible. There is no tank drain that serves that purpose. Doing a vinegar circulate on a storage tank through the drain valve is not the procedure in the flush guide and can leave acid where you did not intend it.

Once a year, or more often on hard water

Pick a month when a cold house will not freeze an emptied tank, and when you can stay home while the tank refills. The procedure, including the plastic drain valve that may not reseal, is how to flush a tank. Hard water shortens the interval. The grains-per-gallon question and what a softener does to an anode are in hard water and scale. If you do not know the hardness, a cheap titration strip on the cold inlet is enough to choose an interval. You do not need a lab before the first flush.

The anode is not part of the flush, even though the tank is open in a related way. Pulling the rod needs overhead clearance or a segmented rod, a socket that fits, and the judgment to stop if the hex will not break free. That job is anode rods. On softened water or if the hot side has started to smell like sulfur, do it sooner than the three-year mark many people use. Do not remove the rod and put the hex plug back as a permanent “fix” for smell. The tank then rusts without a volunteer.

The relief valve is a safety device, not a maintenance accessory you can delete when it weeps. Read how to test it before you lift the lever. Some valve and heater manuals want a periodic test. Some warn that the test itself knocks scale into the seat and starts a drip that means replacement, not another test. Know which instruction is printed on your valve. If you are not prepared to replace a valve that fails the test, have a plumber do the test and the replacement on the same visit. Diagnosis of a valve that is already dripping is why it drips, including the expansion tank a closed system needs.

Tankless and heat pump items on the same calendar

Tankless scale is internal. You will not see it in a drain pan. You will see longer waits, lukewarm water at flows that used to be fine, whistling, and eventually a lockout. The pump, the hoses, the isolation valves, and the vinegar interval are how to descale a tankless heater. If the unit has no service valves, the first “maintenance” is having those valves installed so the next descale does not require cutting pipe. That installation is plumbing work.

A heat pump water heater’s evaporator filter is usually a few minutes with the power off, once or twice a year, more often in a dusty shop. The heat pump guide covers how the machine uses room air so the filter step has a reason. Do not hose the electronics. Do not run the unit with the filter omitted because it was annoying to reinstall. A packed coil becomes a service call, and the resistance elements then do more of the heating, which erases the reason you bought the heat pump.

What to look at without tools

Once a season, with a flashlight and the heater cool enough to stand beside:

• The pan, if there is one, is dry, and its drain is not capped.
• The relief-valve discharge still terminates where you can see it, within the limits the permits guide describes, and nobody has added a valve.
• Combustion air openings on a gas heater are not blocked by storage, and a louvered door has not been swapped for a solid one. That failure mode is in venting and carbon monoxide.
• The area around a gas heater is not a shelf for gasoline, paints, or a bag of rags. Flammable-vapor sensors on modern gas heaters will shut the burner down, and they are right to.
• An electric heater’s cover panels are on. A missing cover is not a convenience.

None of those checks require draining the tank. If any of them fail, fix the condition or call someone who can. Do not add them to a punch list and keep using a blocked flue.

What maintenance will not fix

A tank that is already leaking from the shell will not heal because you flushed it. A gas valve that will not hold a pilot will not heal because you vacuumed the floor. An undersized heater will not grow a larger first-hour rating because the anode is new. Maintenance slows the avoidable failures. Age, a split tank, and a house that added a bathroom are replacement problems, handled in repair or replace and how long heaters last.

If a step in a guide does not match the manual hanging on the heater, stop and follow the manual. Send the difference to the contact address so the general step can be narrowed.

Sources

Department of Energy, Energy Saver, water-heating maintenance themes in “Which Water Heater Is Right for You?” Manufacturer owner’s manuals for flush intervals, anode access, and tankless isolation valves (see A. O. Smith at hotwater.com, Rheem at rheem.com, Bradford White at bradfordwhite.com, Rinnai at rinnai.us, and Navien at navieninc.com). ICC code notes on relief-valve discharge, linked from the permits guide.