Furnace Troubleshooting and Repair Tips

Steps to Take for Troubleshooting and Repairing your Furnace

By Mark J. Donovan

The best furnace troubleshooting advice I can offer you is to make sure your furnace is serviced once a year. I typically have my furnace serviced in the early fall before the cold weather starts. By servicing your furnace annually you can mitigate the risks of waking up to a non-working furnace in the dead of winter.

Basic Furnace Maintenance

If you have a forced hot air furnace make sure to change out the air filters a couple of times a year. This is an easy diy project and will take you all of about 10 minutes and $15 of material.

Just check on the air filter size before going down to your local home improvement center and purchasing a replacement one.

Also, at the same time you’re replacing the air filter, grab your vacuum cleaner and vacuum around the furnace’s blower. In addition, and if you feel up to the task, slip out the fan unit and clean the fan blades with a small brush and then vacuum up all of the dust and lint in around the fan unit.

Check the Fuel

Make sure there is fuel for the furnace. This is the most common problem with furnaces. People forget to fill the gas or oil tanks.

Pilot Light is Out

With older furnaces they may have a pilot light. If the pilot light goes out it may be that the thermocouple may be damaged or loose, the flame set too low, and/or the pilot orifice may be clogged. Use a small thin wire to unclog a constricted orifice, however first make sure to turn the gas off to the furnace.

If the flame appears to be too low then see if you can find a screw to adjust the height of the flame. Read the furnace owner manual to see where the screw is to adjust the flame height.

Furnace Not Putting out Enough Heat

If the furnace operates but fails to heat the home adequately check to make sure all of the registers are properly opened. Also make sure the blower/fan assembly associated with the furnace is function properly. Most importantly, make sure the thermostat is set properly.

Furnace Won’t Turn On

Make sure the furnace switch is in the ON position. Also check to see if there is a red reset button on the furnace that needs to be depressed. The furnace’s motor may have overheated, or become overloaded, and the furnace’s on-equipment circuit-breaker may have popped. Also check the main circuit panel box to see if the furnace’s circuit breaker has popped. Try resetting it and see if the furnace will restart.

Smell of Gas

If you have a gas heated furnace and smell natural gas in or around your furnace or home, leave your house immediately and do not turn off any lights or throw any electrical switches. Also, leave the doors open when you exit the house.

Hot Air Heating System Furnace

Once out of the house, turn off the gas to the home on the exterior of the house, and call (from outside the home) the gas company and/or the fire department. Do not re-enter the home until one of these two have confirmed the house is safe to reenter.

Blower not Blowing Air

If the furnace runs but the blower doesn’t move air check to see if there is a broken belt associated with the fan assembly. If a belt is broken find a replacement one and make the repair. Replacing a fan belt is easy to do. You may need to temporarily adjust the motor mount to slip the new belt over the pulley system. Once the belt is in position relocate the position of the motor and tighten up the bolts associated with the motor mount.

Oil Burner Not Working

Make sure that the fuel oil filter is clean if you have an oil burning furnace. Heating oil can be very dirty. If the filter becomes clogged it will starve the furnace of oil. Similarly dirty oil can cause the oil jet inside the furnace assembly to become clogged. It is best to call in an oil furnace technician to make these types of repairs.

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