Heating Troubleshooting Checklist - Troubleshooting Heating Systems

Heating Troubleshooting Checklist

All Heating Systems

THERMOSTAT CHECK

Is the system selector switch in the "heat" position?
Is the temperature set at least 3 degrees above current room temperature?
If your thermostat is electronic, are the batteries charged? Is the display showing?
Forced Air Furnaces Only. If your thermostat has a switch to control the furnace fan, switch the fan "ON". (This switch will usually be located at the bottom of the thermostat, closer to the left side and will be marked "ON" and "AUTO".) Listen to hear the furnace fan coming on. If you cannot hear the fan, go to one of the supply registers and see if you can feel any air coming up. If the fan is not running, there may be no power to the furnace.
If the thermostat is set properly, next step is to check to see that there is power to the furnace.

ELECTRICAL CHECK - FURNACE

Your heating system may be equipped with an emergency shut-off switch for the furnace. If your system is so equipped, locate it and make sure it is turned on. In most homes the emergency shut-off switch looks just like a regular light switch and will be located on the side or close to the furnace. (Sometimes there is a second switch at the top of the basement stairs) It is quite common for this switch to be turned off accidentally. If the switch is ON, but the fan still doesn't operate, proceed to the ELECTRICAL PANEL CHECK.
Some heating systems also have emergency cut-out switches that are activated when a door or service panel is removed. Often the furnace door is not replaced properly after a filter cleaning and the cut-out switch will prevent the furnace from coming on. Check to make sure all access doors are properly secured and fitted.
ELECTRICAL PANEL - FURNACE

Here you are going to make sure that the main power is on to both the furnace and air conditioner. Locate the breaker or fuses in your home's main electrical panel for the furnace and air conditioning unit. Make sure the breakers are not tripped or the fuses are not blown.

If your home has breakers, check to see if any are tripped. If a breaker has been tripped it will be in a position that is between ON and OFF. Reset the breaker (turn all the way OFF, then back ON).
If your home has fuses, check to see if the fuse for the furnace is blown. If so, replace it with the SAME SIZE fuse. Do not increase the size of the fuse.
WARNING: If a breaker keeps tripping or a fuse keeps blowing, you should contact a qualified service technician to inspect your system to determine why you are having problems.
ELECTRICAL CHECK SUMMARY

If you have determined that there is power to the furnace and you are still not getting any heat, look for any troubleshooting guides that came with the furnace for any additional help. If all else fails, then it is time to call your service contractor.

All Heating Systems

IGNITION CHECK

If your unit seems to be operating, but not producing any heat, the furnace may not actually be firing. If this is the case:
Check the following:

Do you have fuel? This may sound a little silly, but you'd be amazed at how many service calls are caused because the furnace ran out of fuel. If your unit is oil, or propane fired check the level of fuel in the tanks. If you ran out of fuel, ordered some more, and now your furnace will not start, your unit may have to be reset. Some systems have a red reset button on the burner. Other sysems can be reset by turning system power off then back on.If it is oil-fired, the pump may need to be primed. Check with a service technician.
If your furnace is a gas, standing pilot (one that is on all the time) look inside your furnace to see if you can see it. If not follow the instructions on the furnace to light the pilot. If after following instructions and the pilot will not light or stay lit, call a service technician.
In most furnaces and boilers, you can tell when the fuel is being ignited. Turn the furnace off at the thermostat and go to the furnace. Have a friend of family member turn the furnace on at the thermostat, can you hear the furnace ignite the fuel?

OTHER COMMON PROBLEMS

Broken or extremely loose fan belt.
Bound or tight blower motor - With power OFF to furnace try to turn blower shaft (should spin freely).
Bound gas inducer motor - If the furnace isn't working but the inducer is very hot, it could be stuck.
Broken gas ignitor.
Termination kit for Gas, PVC sidewall vented furnace is blocked by snow or another obstruction.
A completely clogged air filter can cause a no heating problem.
PLAN AHEAD TIP

You should get to know your heating system BEFORE it stops working for you. Listen for the various sounds it makes, how long it stays on and where everything is. If you take a few minutes to prepare, you'll be much better prepared if something goes wrong. If you're unsure where things are, ask your service technician for a tour on the next maintenance inspection.

HEAT PUMP TIPS

For heat pump tips and maintenance plus everything else you have ever wanted to know about heat pumps, check out our Heat Pumps 101 page.

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