How to maintain your forced-air heating system

July 27, 2015

Simple Steps for System Care

If the thought of maintaining your forced-air heating system fills you with dread, relax. There are simple steps to take care of it.

How to maintain your forced-air heating system

Blower Cleaning

A thorough cleaning of your furnace blower should be part of your annual service. If you do it yourself, take care of the following for effective cleaning:

  • Turn off the power switch that controls the furnace and open the blower compartment.
  • Vacuum the fan blades and the blower housing to remove as much dust as you can.
  • If a vacuum attachment won't reach, use a bottle brush or rag-wrapped stick to clean them.

Blower Motor Lubrication

As part of an annual service, the blower motor on an older furnace should be lubricated. If you are doing the job yourself, you need to know that most of these motors have small visible oil ports covered with caps or rubber plugs.

  • Lift the cap or plug and add several drops of oil into each hole.
  • Don't overfill. The blower motors on newer furnaces have permanently lubricated bearings that don't need so much oiling.

Squeaking Blower

In older furnaces, the blower has a belt that connects the cage to the motor. If you hear squealing or if the airflow seems weak, the belt may need inspection.

  • Turn off the power switch that controls the furnace and open the blower access panel.
  • Inspect the belt with a flashlight. If it's in bad shape, remove it. You can usually remove and reinstall a belt by pushing it over the lip of the motor pulley while turning it. Purchase an exact replacement at a heating supplier.
  • While checking, take a look at the belt's tension by pressing down on it in the middle of its span. It should yield about one centimetre. It’s important to note that many units have an adjustment bolt on the base of the motor that moves the motor in or out to tighten or loosen the belt tension. On others, you loosen the motor-mounting bolts and move the motor a little.
  • A motor that's not tightly bolted in place or by belt pulleys that don't line up can also cause blower noise or weak airflow. If you notice that the pulleys on the motor and blower don't line up, loosen the set screw on the motor pulley and move the pulley.

System Balancing

A final note on uneven heating; you can alter this by adjusting registers but a more efficient way is to change the dampers within ductwork. Dampers are flat panels that pivot inside the duct to control the airflow and are usually located close to where the ducts branch. They are adjusted by a handle on the outside of the duct. You may find that balancing a forced-air system can take a couple of days so make sure you have the time to do it thoroughly.

Simple Method

Get hold of a few inexpensive same-model thermometers and place one in the middle of each room at table height. Following this, open all the registers and dampers. Set the thermostat to 20°C (68°F). and start the furnace. After a half-hour, partly close the dampers for the warmest rooms. Continue to readjust the dampers until each room is at the desired temperature.

Recording Results

When you finish, mark each damper handle's position. If the system also cools, balance it separately for the cooling season. This is vital for an efficient forced-air heating system as a room that catches the sun may need more airflow to cool down in summer than it needs to warm up in winter.

Efficient System

Maintaining your forced-air heating system is a multi-staged task which needs attention. If you follow the necessary steps, you will have a comfortable home all year round.

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