You live in a house in North America with a 75-gallon power-vented gas-fired hot water heater.

The house has no chimney, which is why the power-vent feature is useful.

The instruction manual (PDF) states that the water heater works like this:

  • When the water in the heater's tank isn't hot enough, the water heater starts up. It lights the burner and starts a fan motor.
  • The burner heats the water, but it produces some exhaust gas.
  • The power-venting blower fan forces the exhaust gas out through the side of the house.
  • Once the water is hot enough, the burner and the fan motor shut down.

The water heater does have an electronic ignition system, but R' Mordechai Frankel writes that this is no problem.

You're worried about the blower fan motor. If you use enough hot water on Yom Tov, the fan motor will eventually start up along with the rest of the water heater. I know that it's fine to enlarge a fire during Yom Tov; but is it also okay to (indirectly) make an electric fan motor start and stop?

  • Possible duplicate of Electronic cigarettes on Yom Tov – Al Berko Oct 19 at 17:51
  • Isn't this similar to a refrigerator motor os Shabbos or Yom Tov which is OK? Note that the blower motor does not start at once or even every time. – sabbahillel Oct 19 at 23:53
  • @sabbahillel: Maybe. But please note: There's a small minority of frum Jews who avoid opening the fridge on Shabbat except when the compressor motor is already running. – tealhill Oct 20 at 4:31
  • Dear @AlBerko: The e-cigarette question is asking about activating a heating element on Yom Tov. My question is asking about (indirectly) activating a fan motor on Yom Tov. Are you suggesting that the halacha regarding heating elements might possibly be identical to the halacha regarding fan motors? – tealhill Oct 20 at 4:35

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