The Heat Is On

House air flow

Your home heat is probably on while you are reading this; living in Canada and given the time of year.We experience full-blown winters in this country and having some way to heat our homes is essential for survival.  We are going to explore the most common types of fuel-burning heating appliances, how they work, and their typical maintenance requirements.  Keeping your home warm and safe requires some basic understanding of your heating system.

The most common modern heating fuels in Canada are gas (natural and propane), oil, electricity, and wood.  These fuels can be used with radiant heat, warm air, and hot water (hydronic) systems.

When heating air, there are two ways to distribute that warm air – convection and forced air.

Forced Hot Air Systems

Many Canadians heat their homes with Forced Hot Air (FHA) furnaces. These furnaces consist of a burner, a contained burn chamber, an ignition device, a heat exchanger, a vent for exhaust gases, a fan compartment, and a duct system for distribution and return of the circulated air.

Each furnace is designed to use a specific fuel type. The burn chamber can use wood, oil, or gas to fuel combustion.  Electric furnaces do not need a burn chamber or exterior venting.  Some furnaces may have two burn chambers allowing them to burn wood in one and oil or gas in the other.  In modern systems, the burner ignition device for oil or gas systems is typically electrical, while wood must be ignited manually as you would in a fireplace.  The ignition timing is controlled by a thermostat (at least one) that activates ignition when the home's air temperature drops below the set point determined by the home's occupants.

Combustion creates hot exhaust gases which travel through the heat exchanger on the way to the vent system, which can be a chimney or a side vent.  Both these vent systems exhaust the combustion gases safely to the exterior.  The heat in those exhaust gases is passing through and captured in the heat exchanger which resides in or very near the fan compartment.  The fan pulls household air past the hot heat exchanger and that heated air is pushed into the distribution ducts which deliver the warm air to each room in the home.  As the air in the home cools, it is pulled back into the system via return air ducts with grates located on or near the floor; ideally at least one return vent is located on each level of the home.  The return air is recirculated past the heat exchanger and the loop is repeated.

To maintain the system at peak efficiency and safety, your furnace should be inspected and serviced annually by a qualified burner technician.They will measure the content of the flue gases to determine efficiency, check and/or replace fuel and air filters, and examine your venting system and fuel supply components.They will also confirm that no harmful exhaust gases (such as carbon monoxide) are leaking into the air circulating over the heat exchanger.

Older gas furnaces in particular have a predisposition to corrode metal heat exchangers.  One of the by-products of gas combustion is water.  The moisture in the exhaust gases that pass through the heat exchanger may condense on there as it cools.  Over time this can corrode the heat exchanger and cause pinhole perforations which allow exhaust gases to leak into the air being passed through the fan compartment.

Annual inspection and servicing will minimize fuel costs and make your home safer and more comfortable.

Hydronic (hot water) Heating Systems

Hydronic heating systems do not heat the air directly like an FHA furnace.Instead, water is heated by a boiler and the hot water is distributed via pipes throughout the home.We will discuss distribution methods a little later.

There are two main types of boilers; floor-mounted or wall-mounted. These boilers are typically installed in a utility room in the basement or off the garage.

Floor-mounted boilers usually use oil, gas, or wood for combustion fuel. There are also dual fuel units and electrically powered boilers, although these are less common.  Floor-mounted boilers tend to have larger volumes of water stored in them, compared to wall-mounted units.

Wall-mounted units are more compact and have minimal water storage capacity.  Rather than store hot water in a reservoir coil inside the boiler, wall-mounted units will heat the water on demand as required by the temperature setting on the thermometer(s).  They can use gas, oil, or electricity to heat the water that is circulated in the system.Like furnaces, any fuel burning boiler must vent combustion gases to the exterior via a chimney or a side vent.Using oil, that side vent must be metal; with gas, it can be an appropriate grade of plastic.

Both boiler types can use one of two methods to distribute heat throughout the home.Originally, cast iron radiators were used to supply heat in each area of the house.They were hot enough to radiate heat that warmed people and objects in the room (and to some extent the air), but proximity was a factor that determined the level of comfort.Cast iron radiators take a long time (and a lot of fuel) to reach their peak efficiency, so you should not operate them with frequent temperature adjustments at the thermometer.

The modern baseboard type of radiators use convection to pull cooler air in at the bottom and push the heated air out the top.  This is the most common means of heat distribution in modern hydronic heating systems. They can react quickly to revised temperature settings, so you can reduce heating costs at night while you sleep and have the home warm up quickly in the morning.  These installations lend themselves to having multiple zones throughout the home; each zone having its own thermostatic control.  When used properly, they are more efficient than cast iron radiators.

Another way to use hot water to heat homes is growing in popularity.  In-floor radiant distribution systems still use boilers to heat the water, but they distribute the heat though a network of plastic pipes located in or under the floors of the home.  These systems require a knowledgeable technician to design the pipe layout for each room of the house, to maximize comfort and efficiency.  These installations also lend themselves to having multiple zones.Radiant heat will warm the objects in the room rather than the air.  Proponents find that this method is more comfortable for occupants than warm-air heating.  These systems also have the advantage of being quieter that other methods, but because they are heating a large mass (the floor), efficiency is greater when minimizing variations in temperature settings.

Maintenance of hydronic heating systems may involve two or more technicians; one for burner maintenance and another for inspecting and maintaining the water related components.  So a burner technician and a qualified plumber or pipefitter could be needed.However, you may find plumbers that have taken the time to also qualify as burner technicians.  As with FHA systems, the technician will confirm that all components are performing safely and at optimum efficiency.  This will include the fuel supply, burner, venting system, and accessible distribution pipes and radiators.

Between Service Calls

Depending on which system you are operating, there are things you can do to keep the home safer and healthier:

Forced Hot Air Systems

These systems always contain an air filter, usually located in or very near the fan compartment of the furnace. The fan compartment cover is usually easy to remove to access those filters. Different filter types perform more or less effectively, but they all are designed to trap dirt, dust, and hair as the returned air passes through them on it way to being reheated.  The majority of these air filters are disposable and inexpensive and readily available at most hardware/home retailers.  Depending on a variety of factors, such as the presence of pets that shed hair, or hobbies or sports that may create dust, you will want to replace these disposable filters every 3 to 6 months.  There are also more permanent filters available, and these are washable.  These should be cleaned every 3 to 6 months as well.

Hydronic Heating Systems

While these systems do not move huge volumes of air around your home, you need to be mindful that they do circulate large volumes of hot water in the pipes throughout the house.  Undetected leaks can cause a great deal of damage to the home, so you should routinely check connections near your boiler, and wherever there are connection points such as at radiators or manifolds for in-floor systems.  Your service technician can advise you where these points are located.

If you have an oil-fired furnace or boiler, you will also have an oil tank on your property.  These tanks are either situated at an exterior location close to the home, or at an interior location such as the basement or garage. Take note that tanks located in garages must be protected from potential impact from a vehicle.

The two materials used most often to manufacture these tanks are steel or composite fiber material.You should monitor metal tanks for corrosion; exterior tanks are more vulnerable to this problem.  You also need to take steps to protect fuel lines and their connection points.Your fuel supplier can advise you on the best means of protecting the oil tank and fuel lines.  Any new tank installation must meet a rigorous standard and should only be completed by a licensed technician.  Any significant oil leaks in your home or on your property can give rise to catastrophic remediation costs.Many homeowners are moving away from oil-fired heating systems to eliminate this risk.

Any home with a fuel burning heating system, regardless of whether it is oil, gas, or wood needs to have carbon monoxide (CO) detectors located near the home's bedrooms.CO enters the home via heating systems that are not properly venting combustion systems.CO gas is colourless and odourless and mixes freely with air.  The detectors are placed near bedrooms to alert sleeping occupants to the presence of CO.  Most people who succumb to CO are sleeping and often cannot be aware of the symptoms of exposure (sleepiness, headaches, nausea).  They simply never wake up.

There are many different heating systems in the present marketplace.If you are looking to replace a fuel burning system with an electrically based system, some of these may be able to use all or part of your present distribution system.Also, modern heat pumps are very efficient and both heating and cooling your home.Split system heat pumps are a good alternative even if you are not looking to replace your present system as the operating costs compare favourable to almost any other system.

Stay warm and be safe this winter!

Illustration courtesy of © Carson, Dunlop & Associates Ltd. 2022

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