-No Heat From the Furnace
It’s the middle of the night and the house is cold and the furnace isn’t putting out any heat. Screaming won’t help.
There are several causes why your furnace isn’t putting out enough heat. Most heating system failures are caused when the thermostat malfunctions, a circuit breaker or fuse is tripped or blown, or the pilot light has gone out.
- The Thermostat is set too low and/or isn’t calling for heat.
Check your thermostat and make sure you have it set on heat (not cool). Then check to make sure you have it set at a comfortable temperature (65 – 75 degrees F).
- The Thermostat isn’t functioning correctly.
If everything is set correctly, try moving the temperature setting up or down a few degrees. If that doesn’t work, try taking the cover off of your non-digital thermostat and blowing out any dust that has accumulated behind the cover. The dust might be contaminating the contact points. This won’t work if you have a digital thermostat. If that doesn’t work you may need to replace your thermostat or have a furnace technician check things out.
- Natural gas supply has been disrupted
Check your natural gas or propane supply lines. Make sure the supply valve is open. If you use propane, make sure your tank isn’t empty.
- Pilot light is out.
Relight the pilot light (see how to relight your pilot light on this website.)
- Your furnace isn’t working.
The gas is on, the pilot light is burning and the thermostat seems to be OK…
Very rarely, something (small critters, filters, etc.) can get into the mechanical system and jamb either the fan or the fan belts. Check to make sure that something isn’t jammed into your fan-belts or blower fan cage. Also, check to see that the fan spins easily – if a bearing has worn out, it will cause the fan to drag. Any of these things can result in a circuit breaker/fuse blowout and/or the motor overheating (which will cause it to shut down).
If there isn’t anything jamming the fan, there must be something wrong with the power to the furnace.
1. Be sure the furnace’s power switch (on/off switch) is turned on; it is usually located next to or inside the furnace cabinet. If it isn’t on, turn it on, and wait for the furnace to engage.
2. Some furnaces have a fuse at their control box (next to or connected to the furnace on/off switch). Turn off the power to the furnace at the main electrical panel or sub-panel. Look for a fuse in the power switch. If there is one there, it may have blown. Replace the fuse (be sure to follow the instructions in your owner’s manual).
3. Check your circuit breaker panel and re-set any tripped breakers or replace any blown fuses. Check both the main electrical panel and any secondary sub-panels that supply power to the unit. If (after you reset or replace the fuses) the circuit blows again, there may be a short in the electrical system for the furnace or something jamming the blower fan/ fan belts/ fan motor in some way.
4. The motor may need to be reset because of an overload. Look for a “Reset” button (usually a small red button) near the blower motor’s housing and, if you find it, press it. If the motor feels warm (or hot), you may have to wait about 30 minutes for the motor to cool, and then try the “Reset” button again. Whenever you need to reset the electrical motor, check to make sure there is nothing jamming the motor, fan and that the fan spins easily.
CAUTION:
The electrical power to a furnace can be deadly. If you don’t have an owners’ manual or are unclear about what it will take to do any of these steps, call a furnace repair technician.
