My water heater tank started leaking so we shut it off until we find the money to replace the water heater tank. However, we noticed that as soon as we shut it off, there is no heater in the house. Are these connected? I would've never thought so.

I have RHEEM 40 gallon gas water heater tank, model XG40t06pv40u0

  • 2
    Do you know how the house is heated? Do you have radiators in the rooms or just vents? 40 gallons seem a bit small for house heating plus hot water combined.
    – crip659
    Feb 1 at 18:13
  • 2
    Do you have some other heating system for your house? Some properties have a "combi-boiler" that heats water both for domestic use (washing dishes, hands, showers, etc.) and for heating purposes (running through radiators or a water/air heat exchanger then blows hot air thought the house). There is no indication, however, that this particular RHEEM is a combi-boiler, so it's not likely.
    – FreeMan
    Feb 1 at 18:13
  • 2
    1) How did you shut if off? Did you use the red switch/knob on the side of it? Or did you shut off the electric or gas supply somewhere else? 2) How many pipes emerge from the heater, is it 4 (cold, hot, gas, pressure) or 6 (two more for home heat) ? Take a pic if unsure and "Edit" your question to paste it in.
    – jay613
    Feb 1 at 18:35

2 Answers 2


Wild guess, but....

There are four ways to shut off a water heater:

  • Electric (not the case here) - thermostat to OFF
  • Electric (not the case here) - turn circuit breaker OFF
  • Gas - thermostat to OFF
  • Gas - close gas valve

With electricity, unless things are wired really strangely, it is usually very obvious which breaker is for which appliance, and you wouldn't (except in an emergency) hit the main breaker to turn off one circuit.

However, with gas, it might not be really obvious which valve controls which appliance (water heater, furnace, possibly clothes dryer). Plus there can be multiple valves, some of which control single appliances and some of which control multiple appliances. So it is possible that you turned off a gas valve near the water heater and that it actually turned off both the water heater and the furnace. In that case, the furnace will still go through some of the motions of trying to turn on but never actually produce any heat.


There are setups that use the main boiler/furnace to heat a pumped loop which then indirectly heats the hot water tank. I have one in my gas-fired system, a friend has one in her oil-fired setup. Done right, with a high efficiency main burner, this can save energy compared to a tank with its own heat source, and sometimes have a longer lifespan.

So yes, heating and hot water can be interconnected. Whether they are in your house, we can't tell without more information. Photos could help a lot.

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