Checking a Standing Pilot Gas Furnace

February 4th, 2010

The limit of most people’s knowledge of gas furnaces begin and end at the thermostat. You feel cold and turn the thermostat up and go back to what you were doing. A few minutes later, you’re still cold and you can’t hear the furnace. You check the power is on and move the thermostat a bit higher. Still nothing. If this is the limit of your knowledge, here is where you should call a professional.

If you’re the enthusiast or DIY type then read on for some important information that might save your eyebrows. While we really would suggest called an engineer right now, we understand that there are plenty of people out there who want to learn more or who want to have a go themselves. On the understanding that on your own head be it, read on.

The first thing to do is recheck the thermostat. Check that it’s definitely switched on to a temperature warmer than it is now. Then go to the furnace and check the filters. A dirty filter can cause the furnace to either work inefficiently or not at all. Clean the filter or replace it with a new one. Then check the mains power. Make sure the furnace is powered. Many will have readouts or lights to indicate power.

If there is no power, check the fuses from the main switch box all the way to the gas furnace. Most will have a switch with a red cover plate, which should be switched to the on position.

If power is good, make sure there is gas. Make sure your propane tank has gas in it, or that your gas meter hasn’t been locked and smell for gas. There will be a valve on the gas line next to the furnace, check that’s in the on position too. This is your gas-cock and the handle or knob should be parallel to the line in indicate it’s open. Next check the gas valve, this is inside the panel next to the burners. There should be a marked on position.

Now here it gets a little trickier. We again suggest calling an engineer, but if you want to keep working on it, read on.

Some gas furnaces have intermittent pilot lights, so you won’t see them on all the time. Don’t try to light an intermittent pilot. To find out if you have one, take another look at the gas valve. If you have an intermittent pilot light, there won’t be a pilot position on the valve. If you have one of these, stop here and call that engineer.

If you have a standard pilot and it isn’t lit, you can light it manually. Be careful here, gas and flames and all that. Get a match or lighter, preferably with a long reach. Turn the gas valve to the pilot position, smell for gas, and if there is none, press down on the knob and apply the flame to the pilot. It should light now, you need to hold the knob down for about 20-30 seconds. If the flame remains, you’ve fixed it. If the light goes out try again and if you still can’t get it to stay lit, call that engineer.