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Personal: Residential

Operating and Maintaining Your Heating System

To keep your home heating system operating at top efficiency, you should follow recommended maintenance procedures for cleaning and servicing. For an oil furnace or boiler, this means a thorough cleaning and tuning each spring. Servicing should be carried out for gas furnaces and boilers at least once every two years.

Most of the tune-up should be carried out by a qualified service technician or heating contractor, but there are many things that a homeowners can do for routine maintenance.

Forced-air systems

IMPORTANT! Before opening the access panel to the furnace to inspect the filter or circulation fan, turn off the electric power supply to the equipment.

Air filters -- Few homeowners give their furnace air filters the attention they deserve. Filters must be cleaned or replaced once a month. Permanent filters, which are made of aluminum or plastic mesh, can be washed. As they are coarser than fibreglass filters, they catch fewer impurities.

If you have installed an electrostatic air filter, you do not need to use a standard filter as well. Do not forget that electrostatic filters must also be cleaned regularly following the manufacturer's instructions.

Fans -- Besides a superficial vacuuming, there is little you can do to maintain a direct-drive furnace fan with an internal motor. On the other hand, if you have a fan driven by a fan belt, and if the fan is used for ventilation or cooling, have your serviceperson check the tension of the fanbelt.

The AC coil (indoor evaporator) in the furnace or ductwork must be cleaned or vacuumed as part of furnace servicing.

Grills and vents -- Keep return-air grills and warm-air vents clean and free of obstructions.

Better heat distribution -- Remove any obstructions from the ducts, warm air registers and cold air returns so that the air can circulate freely throughout the system. Use a special water-based duct mastic to seal cracks at duct joints. At the same time, consider insulating as much of the warm air ducts as possible.

Hydronic Systems

IMPORTANT! Turn off the electric power supply to the equipment.

  • Keep radiators free of dust and objects that might obstruct the heat.
  • Allow air to flow freely around radiators. Make sure they are not covered by curtains or ventilated wood panelling. Keep furniture far enough away to allow the heat to get into the rest of the room.
  • Bleed radiators regularly once or twice a year unless the system has an automatic bleeding capability.
  • Adjust the operating temperature of the water according to outside conditions. An outdoor reset control can adjust the water temperature to match the changing demand for heat so you will never be too hot or too cold, or pay for heat you do not need.
  • Place foil-covered insulation board between radiators and exterior walls. This will reflect heat back into the room that would otherwise be lost to the outside.
  • Keep the water in the expansion tank below flood level.
  • Insulate hot water pipes.
  • Oil the circulating pump according to the manufacturer’s instructions.

Heat Pumps

IMPORTANT! Turn off the electric power supply to the equipment before you do any maintenance.

Ground-source Heat Pumps

Earth-energy systems require little maintenance on your part. Required maintenance should be carried out annually by a competent service contractor. The work should include the following:

  • Filter and coil maintenance has a dramatic impact on system performance and service life. A dirty filter, coil, or fan can reduce airflow through the system. This will reduce system performance and can lead to compressor damage if it continues for extended periods of time.
  • The fan should be cleaned so that it can provide the airflow required for proper operation. The fan speed should be checked at the same time. Incorrect pulley settings, a loose fan belt, or incorrect motor speed can all contribute to poor performance.
  • Ductwork should be inspected and cleaned as required to ensure that airflow is not restricted by loose insulation, abnormal buildup of dust, or other obstacles which occasionally find their way through the grilles.
  • Be sure that vents and registers are not blocked by furniture, carpets or other items that would impede airflow.

In open systems, mineral deposits can build up inside the heat pump's heat exchanger. Regular inspection by a qualified contractor and, if necessary, cleaning with a mild acid solution is enough to remove the deposits. Over a period of years, a closed-loop system will require less maintenance because it is sealed and pressurized, minimizing buildup of mineral or iron deposits.

Air-source Heat Pumps

Proper maintenance is critical to keep your heat pump operating efficiently and to prolong its service life. A competent service contractor should inspect your unit annually – preferably between the end of the cooling season and the start of the next heating season. The contractor will check the refrigerant level and make electrical or mechanical adjustments.

You can do some simple maintenance yourself. Pay particular attention to filter and coil maintenance. It has a dramatic impact on system performance and service life. Dirty filters, coils, and fans reduce air flow through the system. This reduces system performance and can lead to compressor damage if it continues for extended periods of time.

Inspect your filters monthly and clean or replace them as required by the manufacturer's instructions.

Vacuum the coils or brush them clean at regular intervals as indicated in the manufacturer's instruction booklet. The outdoor coil may be cleaned using a garden hose.

While cleaning filters and coils, pay particular attention to the following:

  • The fan should be cleaned and the fan motor should be lubricated annually to maintain the airflow required for proper operation. The fan speed should be checked at the same time. Incorrect pulley settings, loose fan belts, or incorrect motor speeds can all contribute to poor performance.

  • Ductwork should be inspected and cleaned as required to ensure that air flow is not restricted by loose insulation, abnormal buildup of dust, or any other obstacles which occasionally find their way through the grilles.

  • Be sure that vents and registers are not blocked by furniture, carpets, or other items that can block airflow.

Electric Baseboard Systems

Owners can improve the performance of their heating systems by keeping the heating units clean. Vacuum the elements twice a year to prevent dust buildup. In general, electric resistance heating systems require relatively little maintenance and they tend to last for a long time without requiring replacement.

Auxiliary Components

Hot Water Systems

late your water heater storage tank, especially if it is warm to the touch on the side of the casing. This simple and inexpensive improvement can help maintain water temperature at the thermostat setting. (Not recommended for gas.)Insu

Insulating the hot water tank should save enough money to pay back the costs of materials quickly. You can purchase an insulation kit that contains a vinyl-covered insulation jacket, pre-cut tape and instructions.

Domestic hot water systems consume large amounts of energy: only space heating consumes more energy in the home. The following suggestions can help you save even more on your hot water bill:

  • Insulate hot water pipes that pass through unheated areas or go to washing machines. The insulation should be at least R4 (one inch thick) to be effective. You can use pieces of batt with duct tape, or the wrap-type insulation, but the ideal pipe insulation for existing homes is the snap-on type. These are long tubes slit lengthwise that snap over the piping and then are glued shut. Insulate both hot and cold pipes within 2 metres of the water heater.

  • Install a low-flow showerhead and use aerators in the faucets. These inexpensive gadgets will allow you to do the same job with much less water.

  • Fix leaky faucets. At one drop per second, you are wasting 720 litres (160 gallons) per month – or 16 hot baths!

  • Run clothes washers with full loads, and rinse with cold water.

CAUTION - Insulating jackets are not recommended for oil-fired water heaters. Do not block the airflow to the burner when installing an insulating jacket on a gas-fired water heater. Your local fuel supplier can give you more information on insulating hot water tanks.

Heating Ducts

Insulate heating ducts running through unheated or cool basements. Use aluminum foil duct tape to seal the joints of all heating ducts, whether they are to be insulated or not. Then take 75 mm (3 in.) or more of mineral-fibre batts or blankets and cut them to size. Specially designed batts are available for this purpose. Wrap the insulation around the ducts or install it lengthwise. Cover the entire system and tape the insulation securely.

Note: If you wrap the ducts of a wood-fired furnace within 1.8 m (6 ft.), use only a special non-combustible insulation designed for wrapping ducts.

Check return-air ducts, especially where they pass through crawl spaces or garages, and caulk or tape leaky joints.


If you turn your thermostat down a bit during the day and more at night, you will lose less heat in cold weather. The greater the difference in temperature between inside and outside, the greater the heat loss.

Setback or Programmable Thermostats

If possible, install a clock or setback thermostat. A setback thermostat will automatically set the temperature to predetermined levels. Some thermostats work with a clock timer that allows you at least two setback and reset periods a day. (For example, a temperature reduction could be programmed in to start before you go to bed and end before you get up in the morning. The second setback can reduce house temperature when everyone is out of the house during the day and end just before you arrive in the evening.) ENERGY STAR qualified programmable thermostats save energy by changing temperature settings when you find it convenient to scale back on heating or cooling.


When a furnace operates less often, the chimney can get colder between burns. This can lead to downdrafting and condensation, and damage to the chimney.

The lower flue temperature achieved by the improved efficiency of today’s heating equipment has created the possibility of damage caused by flue gas condensation inside a masonry chimney, particularly one located on the outside wall where it is chilled by exposure to the outside air. Any of the following could be signs of a problem:

  • a white, powdery efflorescence on the outside of the chimney
  • spalling or flaking of the bricks
  • crumbling mortar joints
  • rusting or bending in the metal liner
  • wet patches on inside walls behind the chimney
  • broken or flaking flue liner or interior chimney damage (pieces of tile at the bottom of the chimney)
  • water running out of the cleanout door or around the bottom of the chimney behind the furnace.

If you are concerned about any of these problems, have the entire system, including the chimney, checked by a qualified heating-system technician. Ask what changes may be required so that your system operates at top efficiency.

Other chimney problems

Ventilation and Combustion Air

Both you and your furnace need some fresh air, but most Canadian homes get too much. In fact, 25 percent or more of your home’s heat loss can be due to excess infiltration around windows, doors and other cracks. These drafts not only cost you money, but can make your home unpleasant during the winter.

Air-leakage control can affect air quality and the air needed for combustion appliances. More efficient heating systems, combined with better draftproofing and insulation, can result in less air infiltration. This, in turn, can lead to more humidity, which may be a good thing for some houses but can be a problem in others.

There should be an air-tight seal in every window between the sash and the sill and frame. Doors should also be air-tight.

How tight is too tight? When do humidity and condensation become problems? What are the requirements for ventilation and combustion air?

These are the maximum levels of humidity at which there will be no condensation on double-glazed windows at various outside temperatures.

Outside Air Temperature (ºC)

–30º or below
–30º to –24º
–24º to –18º
–18º to –12º
–12º to 0º

Maximum Inside Humidity at 20ºC (68ºF)

15 percent
20 percent
25 percent
35 percent
40 percent

It can be very difficult to accurately measure and maintain the recommended humidity levels. A simple approach is to let the house become your indicator. If condensation starts to appear on the indoor face of any double-glazed windows (except those in the kitchen and bathroom), you have found the optimal point.

Occasional condensation does not pose a problem. Excessive condensation or frosting is an indication that you should reduce moisture production or reduce humidity levels by increasing ventilation.

Take a systematic look at the moisture balance and ventilation needs of your house. Make a list of moisture sources, symptoms of problems and ventilation requirements. Consider how renovation or retrofit plans will affect the house. For example, if the house already shows signs of excessive condensation, any plans that include making the house more airtight will have to include increased ventilation.

For many older homes, a program of comprehensive air-leakage control will not reduce the air supply enough to cause problems. Most older houses experience too much air leakage, even after air sealing.

Houses Susceptible to Air Quality Problems

Problems may occur even after you have done your best to minimize air leakage. You should be aware of the potential problems, the symptoms to look for and some of the possible solutions.

The following circumstances can make a house more susceptible to problems:

  • The house has electrical heat or a high-efficiency furnace (no conventional chimney).
  • There is competition for air (from fireplaces or powerful exhaust vents, for instance).
  • There are sources of air contamination (such as from smokers or hobbies).
  • Household activities produce a lot of moisture.

Symptoms of Problems

If you are aware of symptoms indicating the start of a problem, you can make adjustments and correct the situation before damage results. Look for these signs:

  • Excessive condensation on double-paned windows
  • Staining and mould growth, which often appears first in bathrooms, closets and on walls or ceilings at corners
  • Stuffy atmosphere and lingering odours
  • Odours from the furnace
  • Backdrafts from the fireplace


If the problem is high humidity, with resulting condensation, you must reduce the humidity level by controlling the amount of water vapour that goes into the air. If the situation is not corrected, serious structural damage may occur. First try following these suggestions:

Keep Moisture Out

  • Cover exposed earth floors in basements or crawl spaces with a moisture barrier.
  • Install a sump pump to remove excess moisture from the soil under the slab.
  • Fix all water leaks into the basement.
  • Do not allow standing water in the house or against the foundation wall.
  • Make sure the ground slopes away from the foundation wall.
  • Make sure that there are properly functioning eavestroughs around the house.
  • Talk to a contractor about installing a heat recovery ventilator (HRV) to increase your home’s ventilation and decrease humidity without wasting energy.

Don’t Bring More Moisture In

  • Do not store wood in the house.
  • Avoid hang-drying laundry in the house.
  • Disconnect any humidifiers.

Get Rid of the Moisture Your Household Generates

  • Use lids on pots when cooking.
  • Keep showers short.
  • Make sure your dryer vents to the outside.
  • Install exhaust fans in the bathrooms and kitchen, and use them regularly.
  • Adjust your living habits to produce less humidity in such activities as cleaning, washing and cooking.

Increasing Ventilation

If you still have too much condensation even after reducing moisture production, or if your problem is one of air quality, you will have to increase ventilation. There are several ways of doing this; the best method will depend on your house, the degree of the problem and your preferences.

If the need for ventilation air supply and distribution is great, a central ventilating system can be installed. A relatively inexpensive and effective technique involves connecting a fresh-air duct to the return-air plenum of a forced-air system. Fresh air is drawn in by the suction of the furnace fan, mixed with house air and preheated by the furnace. Open the damper in the fresh-air duct just enough to prevent window condensation. It will have to be adjusted periodically through the winter. Alternatively, you can install a motorized damper operated by a humidistat control. It will open the damper only when the house becomes too humid.

Other types of whole-house ventilation systems include exhaust or supply fans. These are for very tight houses that require a great deal of ventilation. The air must be distributed throughout the house and in a way that maintains comfort levels. The system should not create strong negative or positive pressures in the house. This means that the inlet and outlet air supply has to be in balance.

Some systems are designed with the exhaust fan in the attic and several ducts pulling air from the kitchen and bathrooms. Many central ventilation systems use a heat recovery ventilator that typically recovers 70 percent of the heat from the exhaust air and transfers the heat to the incoming air or to the hot water supply. Central ventilation systems should be designed and installed by a professional.

Combustion Air

Furnaces, fireplaces, wood stoves and any other fuel-burning appliances also require air for combustion and for diluting and exhausting the products of combustion out of the house. Without enough air supply, the chimney or flue could backdraft or spill dangerous gases into the house.

Backdrafts or spillage may be caused by competition for air. A roaring fireplace, a powerful kitchen ventilator, a barbeque range and or even a clothes dryer vented to the outside can exhaust air from the house. If a house is too tight, air could be pulled back into the house through the chimney or vent, resulting in backdrafts or spillage.

Some of the signs of combustion air problems include the following:

  • back-puffing of the furnace, indicated by soot or staining around the air intake;
  • unusual odours from the combustion appliance;
  • difficulty starting or maintaining a fire;
  • frequent headaches or nausea experienced by people in the house;
  • Carbon monoxide (CO) detector readings.

Carbon monoxide (CO) detectors

Because modern houses are more airtight and have more powerful air-exhausting systems, there is a greater chance that combustion products – sometimes containing deadly carbon monoxide gas – will build up to dangerous levels. A certified carbon monoxide detector located close to fuel-fired appliances (such as furnaces, fireplaces, space heaters, wood stoves and gas or propane refrigerators) will signal a potentially dangerous situation that must be corrected immediately.

Symptoms of low-level carbon monoxide poisoning are similar to those of the flu – headaches, lethargy and nausea. If your carbon monoxide detector goes off, leave your home immediately, call your gas distribution company and seek medical attention.

If you operate a conventional wood-burning fireplace (which can often leak carbon monoxide), install a carbon monoxide detector near the fireplace.

Carbon monoxide detectors are available at most hardware stores. Properly installed, these detectors will help protect occupants from accidental asphyxiation due to a failure or malfunction of combustion equipment or the penetration of automobile fumes from an attached garage. They should be installed in any home with combustion equipment or an attached garage. If you are replacing your heating system, consider buying a system that reduces the amount of combustion and dilution air from inside the house. Standard- or high-efficiency heating systems or integrated heat pump systems are possible solutions.

Wood fireplaces are among the worst culprits for robbing household air. The heat they supply does not make up for the heat lost when house air is drawn up the chimney. Some accessories – such as tightly fitted glass doors and outdoor air intakes – may nominally improve fireplace efficiency and require less household air, but the heating efficiency remains very low. Opening a window slightly when you operate the fireplace reduces the use of household air.

Oil and gas furnaces may require a free and unobstructed supply of outside air. The size and type of ducting system will vary according to the type of fuel and the location and heating capacity of the appliance. Obtain specific information on all aspects of combustion air supply systems from your local regulatory authority, fuel supplier or heating contractor before work begins.