7. Maintenance

7. Maintenance

Servicing Maintenance

Many gas utilities offer a maintenance service (often through contractors) that includes an annual furnace inspection, cleaning and adjustment, if necessary. This type of annual checkup is highly recommended for both efficiency and safety.

Some of the other tasks that should be performed by a serviceperson during regular maintenance are as follows:

  • inspecting the inside and outside of the vent pipe and stack
  • checking the condition of the furnace heat exchanger
  • checking the safety controls for the exhaust system
  • checking the other safety controls
  • checking the condition of all fan wheels – circulating, exhaust (induced draft fan) or forced (burner) – and cleaning them, if necessary
  • cleaning or replacing the air filter for forced-air systems

Separately, many gas utilities or dealers may also offer a parts-replacement plan, which, for an annual fee, covers repair, adjustment or replacement of controls, motors and parts. As well, they will alter appliances, equipment or piping and turn on gas service if the pilot light has been shut off.

Furthermore, most utilities offer the following services at no charge: emergency services (such as investigating suspected gas leaks or carbon monoxide spillage); estimates for repairs, replacements and alterations; verifying gas meter operation; and finding the location of buried gas lines.

If the furnace's pilot light has been shut off during the summer to conserve fuel, relighting should be done carefully and in accordance with the manufacturer's instructions, which are usually on a metal plate near the furnace burner or gas controls. Shutting off the pilot light for the summer is cost-effective only if you plan to shut it off and relight it yourself. If it fails to relight, you should contact the gas utility and have the relighting done by a qualified serviceperson. A fee is normally charged for this service. While the serviceperson is in your home, ask for instructions on properly relighting the pilot light. You could also ask for a brief inspection of the equipment.

Owner Maintenance

There are a number of maintenance tasks you can do yourself to keep your system working well. But even if you do these properly and regularly, you should still have your system serviced annually by an expert heating contractor or gas utility.


Other than the modern side wall venting furnaces and boilers, gas furnaces and boilers must be vented with one of the following:

  • a double-walled, prefabricated metal B-vent with an aluminum lining
  • a properly sized masonry chimney lined with a clay flue tile
  • a masonry chimney lined either with a B-vent or an approved stainless steel liner

Although a gas furnace vent (chimney) rarely, if ever, needs to be cleaned, it should be checked occasionally for signs of deterioration due to condensation or corrosion. You can check it simply by inserting a mirror in the cleanout opening at the bottom of the chimney on a bright day.

Look for a broken or flaking flue liner, or rusting or bending of the metal liner. Water streaks from the cleanout door or the base vent T can also indicate chimney condensation and other potential problems.

Take a look at the outside of the chimney as well. White or yellow efflorescence on masonry chimneys or deteriorating or flaking brick or mortar can indicate condensation problems in a masonry chimney. Don't forget to look at the outside of metal chimneys as well. Rust marks could indicate the onset of serious corrosion.

The advantage of high-efficiency condensing furnaces is that they eliminate the need for a chimney and are thus vented out the side wall of the house through an effectively non-destructible PVC or ABS pipe. Make sure that the pipe always slopes upwards from the appliance to the outside and ensure that the outside vent terminal is kept free from obstructions, including ice formation.

Certain types of gas-fired systems have special needs that may require your attention. Check your owner's manual or discuss this with your installer or serviceperson.


Cleaning or Changing the Air Filter

IMPORTANT! Turn off the power to the furnace before opening the furnace access panel to check the filter or fan.

Few homeowners give the air filter in a furnace the attention it needs. It should be cleaned or replaced once a month. You can get permanent filters made of aluminum or plastic mesh that can be washed in a laundry tub, but these are not as fine as glass-fibre filters and do not trap as much dirt.

If you have added an electrostatic air filter to your furnace, you do not need a standard filter as well. Remember that the electrostatic filters also need to be cleaned regularly. Check your owner's manual for instructions.

Fan Care

Except for superficial vacuuming, there is no maintenance that a homeowner can perform on a direct-drive furnace fan with an internal motor. On belt-driven fans, some motors have small oiling cups over the bearings on each end of the motor, whereas others are maintenance-free. The ones requiring oiling should be given a few drops of oil once or twice during the heating season and again in the summer, if you use your fan for ventilation or air conditioning. (Check your owner's manual or ask your furnace serviceperson about the type and quantity of oil to use.)

Also, check the tension of the fan belt by pressing it firmly in the centre with your thumb. You should be able to depress it about 20 mm (3/4 in.) but no more than 25 mm (1 in.). The tension of the fan belt can be adjusted by loosening the bolts on the motor mount and moving it forward or backward. Make sure the fan and motor pulleys remain perfectly aligned. This job is best done by a qualified serviceperson.

Care of the Distribution System

Remove obstructions from ducts, warm air registers and cold air returns so that air can move freely around the system. Use a special, water-based duct mastic to seal cracks at duct joints, as described on page 23. At the same time, consider insulating as much of your warm air ducts as you can easily access.


Here are a few things you can do with a hydronic (hot water) heating system.

  • Insulate hot water pipes.
  • Once or twice a year, bleed air bubbles out of radiators so that they can fill with water.
  • Vacuum the radiators.
  • Check to see that the level of water in the expansion tank is below flood level.
  • Oil the circulating pump (according to the manufacturer's instructions).
  • Allow air to flow freely around radiators: make sure that they are not covered by curtains or by ventilated wood panelling, and try to ensure that they are not directly behind furniture so that the heat generated can get into the rest of the room.

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Source: Natural Resources Canada (NRCan) - Office of Energy Efficiency