Kevin O’Connor gets a primer on furnace maintenance from plumbing and heating expert Richard Trethewey. Richard first explains to Kevin how a furnace works before explaining the different checkpoints that an HVAC technician would use to check the furnace.
After that, Richard shows Kevin the dangerous conditions that can exist if the furnace isn’t serviced by a professional at least once a year.
Furnaces are Fairly Simple Devices
Furnaces are fairly simple devices. They operate by a blower pulling air into the furnace through the return side and pushing it out the supply side. As the air exits the furnace, it flows through a heat exchanger, which is essentially a sealed burner, and then leaves the furnace to flow throughout the system. But, as simple as they are, they require yearly maintenance.
A heat exchanger is a burner inside a heating system’s airway in a sealed chamber. Gas enters the heat exchanger and ignites, heating the metal that makes up the chamber. The exhaust exits the unit through an exhaust pipe, all happening without mixing with the conditioned air.
The conditioned air blows across the chamber, which the burner has heated, pulling heat energy from the heat exchanger. As it does, the temperature of the air rises and then disperses that heat energy into the home.
These heat exchangers need to be maintained once a year to ensure that they’re working properly and safely. The technician will check the gas pressure at the supply and the pressure at the valve to ensure that there is the proper amount of pressure at the burners. They’ll also check the safety devices to make sure they’re functioning.
They’ll also do a combustion test in the exhaust to make sure that the system is working properly and burning fuel efficiently and safely.
Air Conditioning Coil
Some furnaces are actually combination heating and air conditioning units. In addition to the heat exchanger, these models have air conditioning coils through which the air passes and cools. These units also need maintenance as their filters need changing.
Many times, homeowners will remove a clogged filter and let the system run. This can be big trouble for an AC coil because these models have tiny fins that clog with dirt and hair easily. The coil can freeze and break in this case, so homeowners or service techs need to remove the gunk and grease with a fin comb or brush and coil cleaner.
Instead, they should simply change the filter once a year to avoid unnecessarily damaging their unit.
The Dangers of Not Maintaining a Furnace
There are actual dangers of not maintaining a furnace. For one, the unit will run less efficiently and the space will take longer to reach comfortable levels. But, more importantly, the unit can become unsafe.
A furnace that hasn’t been maintained properly is susceptible to exhaust issues or cracked heat exchangers. A cracked heat exchanger will allow carbon monoxide-laden exhaust to mix with the fresh air in the home, possibly creating a very dangerous situation.
And this is a situation that a furnace technician would pick up on right away during regular maintenance when they test the supply air and the exhaust gasses for safety.
Richard emphasizes the importance of a yearly service call for furnaces and AC units and what
to expect from technicians when they come.