Furnace Maintenance Made Simple
All types of heating units have a few key components. They are:
1) A cold air return,
2) a warm air outlet,
3) a heat exchanger,
4) a thermocouple (in gas units), and
5) a blower.
The cold air return (sometimes called return air intake, or fresh air return) is a hole or vent that lets fresh air get to the furnace. It should be situated near floor height and free of obstructions. The cold air return will also work if placed higher in the room, but for best operation they should be lower to the floor than the height of the thermostat.
The cold air return typically contains a filter of some kind. This filter catches dust, hair, and other nearly-invisible debris that is floating around even the cleanest home. This filter should be replaced at least twice annually, and ever three months for systems with central air conditioning. You should change the filter monthly for the best efficiency.
Some furnaces will have a permanent filter built into them. Permanent filters require regular cleaning, generally at the same time you are replacing the cold air return filter.
No matter how often or how well you clean the fresh air filters, the circulating air will still contain some small particles of dust that will settle on the thermocouple and the heat exchanger.
The thermocouple is a sensing device in gas furnaces. It opens a valve to permit natural gas to flow through the heat exchanger to be ignited either by the pilot light or the electronic ignition.
Thermocouples and heat exchangers because conduct heat. To conduct heat efficiently, they and need to be cleaned regularly.
Cleaning the thermocouple and heat exchanger involves a few steps. And some precautions to prevent damage to the furnace, or injury to yourself.
1) Be sure to turn off the gas line or power line to the furnace;
2) Have plenty of lighting so you can see what you are working on;
3) You may need both a flat head and a Phillips head screwdriver handy, as well as a pair of pliers;
4) Compressed air, either in a can (with no accelerants such as alcohol or propane) or via a compressor unit;
5) A rag and cool water.
This cleaning should be done prior to heating season, but can be done on a warmer winter day without too much trouble since it only takes a few minutes.
You absolutely must cool down the furnace or heater if it has been operating. The air from the canned air or compressor is cold – you do not want it hitting the hot elements! They can throw off steam, burning you severely. Even if you are not injured, you can crack the heating elements or thermocouple. Sometimes these cracks will be invisible to the naked eye. Even though the furnace may still operate, you have potentially created a dangerous gas leak, and definitely shortened the life of this component.
Use the compressed air on all surface buildups of dust and blow them away from the thermocouple and heat exchanger. Be slow and methodical. You want the heating surfaces open to the air. Not only are you cleaning the surfaces, you are trying to blow free any dust clogging gas jets.
Once these components are free of visible dust, use a damp, not wet, cotton dust cloth (or other low lint wiping material) to gently brush away any clinging dirt. Do not scrub or rub, just gently wipe the surfaces. Do not use any chemicals on the surface, especially alcohol or other combustible chemicals which may linger and be burned off when you re-start the furnace.
Next, make sure the duct from the blower is free of dust and obstructions. Blow free any dust that may have built up on the blower fan and in its coils. Vacuum up any dust remaining inside the unit.
That’s it! The critical components of your furnace are now clean. Your furnace will now operate more efficiently at getting heat into the rooms of your home, instead of heating up accumulated junk on the surfaces of the heating elements.
