home heating question

[JoDog]

Here's a question for any handymen or gals out there:

My apartment has an old, standing pilot light gas furnace. Yesterday, the electrical power to most of the basement where the furnace is located went out. Early diagnosis is that something went wrong with the circuit breaker or fuses that control the power to that part of the building, and only that part of the building.

Whatever happened, my furnace will not turn on. The pilot light is on, everything looks fine, it's just in a part of the building where the electrical power is on the fritz. My understanding was that an older system like this, with an actual pilot light, did not use any electrical power. I have done some reading, and have found out that these old systems were often connected into a nearby circuit breaker. My hunch is that this was done for safety reasons--whatever is causing enough of a problem to trip the circuit posed enough of a hazard to a highly flammable natural gas system that it was prudent to shut the whole thing down until repairs were made.

Please note that the much newer gas-powered water heaters in the basement are working fine.

My questions:
1. Am I wrong that an old standing pilot system would use no electricity? (I need to know this because my landlady is involved, and if she thinks she's paying for any juice to my furnace, things could get ugly.)
2. Is my guess as to why such a system would be patched into a circuit breaker close? If not, why? (Although the answer to number 1 may also serve as answer to this one.)

Thanks.

[evlbstrd]

1. Thermostats are electric. nt

[sasquatch]

2. Your gas valve is probably busted

Might have broken during the outage.

[BrotherBuzz]

3. Forced air or gravity heat?

Forced air furnaces need electricity to run the fan. The thermal coupler at the pilot light works without outside electricity but the furnace will not fire up if there is no electricity to run the fan.

[Mugu]

4. Is the unit forced air or convection, electric thermostat or mechanical?

I have never heard of a safety system like what you describe, but there are many things that I have never heard of. I have a small convection gas heater with a mechanical thermostat that works fine without electricity. In fact that's the reason that I have it because it's not unusual for the power to go out during ice storms around here.

Regards, Mugu

[JoDog]

6. I think

It's convection (without a fan) but I can't be certain. The thermostat is working, so if it is an electrical model, it is apparently getting its electricity from my apartment, not the circuit breaker downstairs. (I know it's working because we had to borrow some space heaters last night, and managed to get the temperature in the apartment up to 65 degrees. The needle on the bottom of the dial-style thermostat moved to show the new temperature in the apartment. So that part of it is working.)

[JoDog]

7. The safety system

I just spoke to a coworker who has experienced a similar situation. According to what he was told by a heating professional, it was not unusual for these older systems to be patched into a circuit braker to make sure the gas was off should there be enough of an emergency that the power went off.

[krispos42]

5. The valve that controls the flow of gas is electric, I believe

Pilot light is basically a tiny, lit gas leak. When the thermostat clicks the heat on, an electrically-operated valve pops open, letting the full flow of gas into the furnace. The gas hits the pilot light and bursts into flame.

If the electric valve isn't opening, then either the thermostat is not telling it to open, the electric valve's power supply is turned off, or the electric valve is broken somehow.

If your thermostat is turned off, or to "Cool" or "A/C", that would do it. If the circuit breaker to the furnace is turned off or tripped, that also would do it as well.

The valve should "click" when the thermostat is turned up.



A non-electrical possiblity is that the valve that controls the main flow of gas is turned off. The gas valve usually has a position where you can keep the pilot light lit but turn off the full supply of gas. Something like "Off/Pilot/On" positions you can turn the knob to. If somebody moved the knob to "Pilot", that would keep the fully flow of gas from happeneing.



More modern furnaces don't use a pilot light. They use an igniter like the kind on your gas grill. When the thermostat turns the heat on, the full gas flow turns on, then the igniter lights the gas.

[JoDog]

8. The main flow valve

is on. The idea that there is an electric valve controlling the flow of gas makes sense. However, I'm afraid that if my landlady hears that, she will get dollar signs in her eyes and demand that I pay her for the electricity the valve uses.

Does anyone know if such valves use a lot of energy? Or is it so negligible that the landlady wouldn't have a case?

[krispos42]

11. It's pretty negligable

It's usually a solenoid valve. With power turned off, a small spring holds the valve closed. When the valve is opened, power is put through an electrical coil that pulls the valve open against the spring. It's very similar to the system that operates a car's power door locks.

It only uses power when the gas is flowing, and it doesn't use very much even then. If you look at the valve you should be able to find some sort of label that tells you how much power it draws.

[likesmountains 52]

9. Try posting this in the DIY forum...they're always helpful

[JoDog]

10. Not a donor

so I'm afraid I can't post in that forum.