Do water heater timers work as advertised?


Do water heater timers work as advertised?

Asked by Stephan Pollard

I am considering installing a timer on our home's gas-fueled water heater. I just purchased a home in Arkansas having a relatively new standard 50-gal gas-fueled water heater storage tank. I am hoping to significantly decrease CO2 emissions and lower the gas bill without having to purchase a very expensive alternative system.

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Michael Holcomb's picture


Unfortunately marketing hype seldom delivers on its promises.

Shutting off a gas-fired water heater for a period oftime when you aren't using hot water will not result in much energy savings.

Baseline heater efficiency

You mentioned that you have a relatively new standard water heater. I am assuming this is a gravity draft waterheater rather than a fan assisted.

  • The gravity draft water heaters are around 50-54% efficient while the fanassisted models range from 10 - 14% more efficient.
  • You didn't mention tank size but that plays a role in efficiencytoo, the larger the tank the greater the heat loss (more surface for conduction).
  • Gas-fired, tankless, on-demandwater heaters offer efficiencies in the 80 - 96% range.

Improving water heating efficiency

Let's look at some options to saving energy with respect to water heaters that do not involve installing a timer orreplacement of the appliance.

Blanket. Install an insulation blanket on the water heater. Adding a layer of insulation will reduce the temperaturedifference (Delta T) between ambient air and the water heater.

  • The lower the Delta T the lower the heattransfer rate (from hot to cold).
  • Insulation blankets are available at most big box stores and are easilyinstalled by a handy homeowner.

Pipe insulation. Insulate all (accessible) hot water lines. Adding preformed pipe insulation (either fiberglass or foam) tohot water lines helps reduce line loss, keeping hot water in the pipes for up to 30 minutes longer thanuninsulated pipes.

Cold water insulation. Insulate the first 6-feet of cold water line (to the water heater) at the top of the tank. Again this is a jobfor a handy homeowner. Make sure you do not install foam insulation too close to the water heater fluepipe or draft hood.

Low flow fixtures. Reduce your use of hot water by replacing shower head fixtures with low flow (1.75 GPM) replacementheads and lavatory faucets with flow rates of 0.5 GPM.

Turn it down. Set your water heater at 105-degress. It takes less energy to maintain 105-degrees than it does 120-degrees plus it is safer (less of a scald hazard).

Flush your water heater monthly to remove mineral deposits from the bottom of the tank. Note that manynewer water heaters are self cleaning so check your homeowner manual.

  • Flushing 1 - 2 gallons of watermonthly from the water heater drain valve will remove mineral deposits from the bottom of the tank.
  • Ifdeposits are allowed to build up they will insulate the tank from the burner making it more expensive toheat water.
  • Tanks that "gurgle or percolate" already have a buildup in the tank and should be candidatesfor replacement if flushing doesn't solve the problem.
  • A word of caution, make sure you have a hose Bibbcap handy in case dislodged mineral deposits prevent the drain valve from closing fully allowing the valveto drip slowly. Caps are available at your local hardware store for around $1.

If it sounds too good to be true

Effective energy savings are rarely about gimmicks or expensive investments.

Conservation is the most effectiveenergy savings option we can take.

When making purchasing decisions always look to products that offer reducedenergy and water use to continually lower your energy use point.