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home heating system options explained by experiences local HVAC pro

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Types of Heating Systems

Central Heating


Most North American homes depend on a central furnace to provide heat. A furnace works by blowing heated air through ducts that deliver hot air to rooms in the house via air registers or grilles. This type of heating system is called a ducted hot air distribution system or forced hot air. It can be powered by electricity, natural gas or fuel oil.

Inside a gas or oil furnace, fuel is mixed with air and burned.

The flames heat a metal heat exchanger in which the heat is transferred to the air. Air is pushed through the heat exchanger by the "air handler" furnace fan and then forced through ductwork downstream of the heat exchanger. At the furnace, combustion products are vented from the building through a chimney. Old "atmospheric" furnaces vented directly to the atmosphere and wasted about 30% of the fuel's energy just to keep the exhaust gases hot enough to safely rise through the chimney. Today's low-efficiency furnaces greatly reduce this waste by using an "inducer" fan to draw exhaust gases through the heat exchanger and induce draft in the chimney.

"Condensing" furnaces are designed to capture much of this escaping heat by cooling the exhaust gases to well below 140°F, where the water vapor in the exhaust condenses in water. This is the main characteristic of a high-performance furnace (or boiler). These usually vent through a side wall with a plastic tube.

New standards for ovens are currently being developed in the United States

Department of Energy, and is expected to be finalized in the spring of 2016. Current furnace standards have not been updated since 1


Heating system controls regulate the ignition of various components system heating and off you go. The most important control from your perspective is the thermostat, which turns the system, or at least the distribution system, on and off to ensure your comfort. A typical forced air system will have only one thermostat.

But there are other internal controls in a heating system, such as "high limit" switches that are part of an invisible but essential set of safety controls.

The best gas furnaces and boilers they have today efficiency over 90%

The efficiency of a fossil fuel furnace or boiler is a measure of the amount of useful heat produced per unit of input energy (fuel). Combustion efficiency is the simplest measure; it's just the efficiency of the system while it's running. Combustion efficiency is the miles per gallon your car travels at 90 km/h on the highway.

In the United States.

S., furnace efficiency is regulated by the minimum AFUE (Annual Fuel Usage Efficiency). AFUE estimates seasonal efficiency by averaging peak and partial load situations. AFUE takes into account start-up, cooling, and other operational losses that occur under real-world operating conditions and includes an estimate of the electricity used by the air handling unit, inductor fan, and the orders. AFUE is like your car's mileage between refueling, including highway driving, and stop-and-go traffic.

The higher the AFUE, the more efficient the furnace or boiler.


Boilers are special water heaters. While furnaces carry heat in hot air, boiler systems distribute heat in hot water, which gives off heat as it passes through radiators or other appliances in rooms in the house. . The colder water then returns to the boiler to be heated again. Hot water systems are often referred to as hydronic systems.

Residential boilers typically use natural gas or fuel oil as fuel.

In steam boilers, which are much less common in homes today, water is boiled and the steam carries heat through the house, condensing to water inside the radiators while it cools. Fuel oil and natural gas are commonly used.

Instead of a system of fans and ductwork, a boiler uses a pump to circulate hot water through pipes to the radiators. Some hot water systems circulate water through plastic pipes in the floor, a system called underfloor heating (see "State-of-the-art heating").

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Important boiler controls include thermostats, water tanks, and valves that regulate water flow and temperature. Although the cost is not insignificant, it is generally much easier to install thermostats and "zone" controls for individual rooms with hydronic systems than with forced air. Some controls are standard in new boilers, others can be added to save energy (see section "Modifications by heating engineers" on the heating maintenance page).

As with ovens, gas condensing boilers are relatively common and significantly more efficient than non-condensing boilers (unless very sophisticated controls are used). Oil-fired condensing boilers are rare in the United States.

S for several reasons related to the lower latent heat potential and increased fouling potential with conventional fuel oil.

Heat Pumps

Heat pumps are two-way air conditioners only (see detailed description in the cooling systems section). During the summer, an air conditioner works by moving heat from the relatively cool indoors to the relatively warm outdoors. In winter, the heat pump reverses this trick, absorbing heat from the cold outside using an electrical system and rejecting that heat inside the house.

Almost all heat pumps use forced hot air supply systems to move heated air throughout the house.

A geothermal heat pump heats and cools in any climate by exchanging heat with the ground, which has a more constant effect. temperature

There are two relatively common types of heat pumps. Air-source heat pumps use outdoor air as a heat source in winter and as a heat sink in summer. Ground-source heat pumps (also called geothermal, GeoExchange, or GX) obtain heat from the ground, where temperatures are more consistent throughout the year.

Air-to-air heat pumps are much more common than geothermal heat pumps, as they are cheaper and easier to install. Geothermal heat pumps, however, are much more efficient and are often chosen by consumers who intend to stay in the same home for a long time or who have a strong desire to live more sustainably. How to determine if a heat pump is right for your climate is discussed in more detail in "Fuel Options".

While an air-source heat pump is installed much like a central air conditioner, pumps from geothermal heat sources require that a "ring" be buried in the ground, usually in long, shallow trenches. deep (3-6' deep) or in one or more vertical wells. The particular method used will depend on the experience of the installer, the size of your lot, the subsoil and the landscape.

Alternatively, some systems draw water from the ground and pass it through the heat exchanger instead of using a coolant. Groundwater is then returned to the aquifer.

Since the electricity from a heat pump is used to move heat rather than generate it, the heat pump can supply more energy than it consumes. The relationship between heating energy supplied and energy consumed is called the coefficient of performance, or COP, with typical values ​​between 1.5 and 3.

5. It is a "steady state" measurement and not directly comparable to Seasonal Heating Performance Factor (HSPF), a seasonal measurement needed to rate the heating efficiency of air-source heat pumps. Conversion between measurements is not easy, but geothermal units are generally more efficient than air-source heat pumps.

Direct Heat

Gas Heaters

In some areas, direct fired gas heaters are popular. This includes wall, pedestal and pedestal ovens, all of which feature no ductwork and relatively low heat output.

Since they have no ducts, they are very useful for heating a single room. If more than one room is to be heated, doors between rooms must be left open or another method of heating is required. The best models use “sealed combustion air” systems, with pipes installed through the wall to both supply combustion air and carry combustion products. These units can provide acceptable performance, especially for cabins and other buildings where large temperature differences between bedrooms and main rooms are acceptable. Models can run on natural gas or propane, and some burn kerosene.

Ventless Gas Heaters: A Bad Idea

Gas or kerosene heaters that don't have a vent have been sold for decades, but we advise against it strongly their use for health and safety reasons. Known by manufacturers as "ventless" gas heaters, they include wall-mounted and freestanding stoves, as well as open-flame gas fireplaces with ceramic logs that aren't actually connected to a chimney. Manufacturers claim that since the combustion efficiency of the products is very high, they are safe for building occupants. However, this statement only holds true if you keep a nearby window open for a sufficient supply of fresh air, which defeats the purpose of supplemental heating. Risks include exposure to combustion by-products, as discussed in Ventilation, and oxygen depletion (these heaters must be equipped with oxygen depletion sensors).

Because of these risks, at least five states (California, Minnesota, Massachusetts, Montana, and Alaska) ban their use in homes, and many cities in the United States and Canada have banned them as well.

Space Electric Heaters

Portable (plug-in) electric heaters are cheap to buy, but expensive to operate. These resistive heating elements include "oil" and "quartz infrared" heating elements. They transform the electric current from the wall socket directly into heat, like a toaster or an iron. As explained later in the "Choosing a New System" section, it takes a lot of electricity to provide the same amount of useful heat that natural gas or fuel oil can provide locally.

A 1500 watt plug-in heater will use almost the entire capacity of a 15 A branch circuit; therefore, adding a lot of extra load will trip the circuit breaker or blow the fuse. The cost of running a 1,500 watt unit for one hour is simple to calculate - it's 1.5 times the cost of electricity in cents per kilowatt hour. At national average rates - 12¢ kWh for electricity - this heater would cost 18¢ an hour to operate and would quickly cost more than its purchase price. On the other hand, for intermittent use, it is the "least harmful" solution, whereas the alternatives would require significant investments to improve, for example, the ducts of a specific area.

Remember that electric resistance heating is usually the most expensive form of heating and is therefore rarely recommended.

"Electric baseboard heating" is another type of resistive heating, similar to a plug-in space heater except that it is hardwired. It has two main virtues: the installation cost is low and it is easy to install individual room thermostats in order to be able to lower the heating in unused rooms. The management costs, as with all resistive systems, are generally very high, unless the house is "super insulated".

Wood and Pellet Stoves

Wood burning can make a lot of sense in the countryside if you like stacking wood and fueling the stove or oven.

The prices of wood are generally lower than those of gas, oil or electricity. If you cut your own wood, the savings can be significant. Pollutants from burning wood have been a problem in some parts of the country, causing the United States Environmental Protection Agency (EPA) to implement regulations regulating pollutant emissions from wood-burning stoves.

As a result, the new models work quite well. Pellet stoves offer many advantages over wood stoves. They are less polluting than wood-burning stoves and offer users better comfort, better temperature control and better indoor air quality.


Gas fireplaces (and most wood-burning fireplaces) are essentially part of the furnishings of a room, providing light warmth (and a means of disposing of secret documents ), but is generally not an efficient heat source. With traditional installations that rely on air drawn from the room into the chimney for combustion and dilution, the chimney generally loses more heat than it provides, as a large amount of hot air is drawn in through the unit and must be replaced with cold outside air.

On the other hand, if your fireplace has a sealed glass door, an outside air source, and a good damper for the fireplace, it can provide useful heat.

State-of-the-art heating

Radiant floor heat generally refers to systems that circulate hot water through pipes under the floor. This heats the floor, which in turn heats the people using the room. It is highly controllable, considered effective by its proponents, and expensive to install. It also requires a highly experienced system designer and installer and limits the choice of carpets and other floor finishes - you don't want to "cover" your heat source.

Contact the Radiant Panel Association (link is external)

Ductless, Mini-Split, Multi-Split. Residential pipelines are relatively rare outside of North America. Ductless heat pumps, which distribute energy through refrigeration lines instead of water or air, are widely used. Extensive field trials in the Pacific Northwest suggest they can perform well in the cold and be very cost effective when replacing electric resistance heating. Like geothermal systems, the relative immaturity of the market ensures that whole-house multi-split systems are priced at full price.

Heat-electricity cogeneration (CHP) or cogeneration for homes is the subject of serious studies in some countries. The basic principle is to use a small generator to meet part of the electrical needs of the house and to recover the waste heat (generally more than 70% of the calorific value of the fuel) to heat the house (hydronic or water systems for air) and produce domestic hot water. These systems are not yet widely available. They are likely to have the best economy in homes with high heating bills because the home cannot be practicably insulated, such as stone or brick homes.

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