How to pick home heating system

We all know how tough winter can be in Canada. So, picking a right home heating system is of great importance. There are a variety of choices on the market, but how do we know which one we should pick if we know nothing about these heaters. Therefore, I just want to make a brief summary of some common types of home heating systems. The information is gathered from the reference websites. Please check these websites if more details are needed.

There are two systems to keep our homes heated: central heating systems and unitary systems. Simply speaking, central heating systems heat the entire home at the same time, while unitary systems are designed to heat individual rooms or serve as supplementary heating. There is no quick formula to determine the proper size of the heating systems since every home is different and heat is lost via different ways for different homes. The best way is still to consult contractors and obtain bids from several contractors. Generally, the capacity of the selected heating system needs to be from 10 to 30 percents higher than the design heat load. It is important to remember that heating systems are only replaced about every 20 years, so you will have to live with your decision for some time.



Now, let's talk about the central heating systems first.

Central heating systems can typically be divided into two broad classes, those that distribute heat by heated air and those that use water as the distribution medium. Electric and gas-fired warmair furnaces, air- and water-source heat pumps, and hot-water baseboard or radiant slab are all central systems. Electric baseboard and electric radiant heating are also used on occasion.

Central warm air systems

Warm-air heating systems include gas-fueled furnaces, electric furnaces, conventional heat pumps, and ground-coupled heat pumps. Ducts provide a passage for heated or cooled air from the heating or cooling unit to and from the conditioned space.

Gas-fueled warm air furnaces:
Natural gas or propane-fired warm air furnace are commonly used. Several manufacturers offer multi-stage furnaces. These units have both a high- and low-heat delivery rating. If it is mild outside, the unit delivers heat at the lower rate. If it is cold outside or the home is recovering from a setback condition, the higher delivery rate is used. The principal advantage is the ability to maintain a more constant inside temperature.

Electric furnaces:
Electric furnaces provide heat by using a series of electric resistance heating elements and a central fan. The fan is similar to a blower in a fuel-fired warm-air furnace. Electric furnaces were once quite popular but increasing electricity prices have made them potentially too costly to operate. In areas where the demand for heat is low or where electricity prices are low, they are still quite cost effective.

Air source heat pump:
Air-source heat pumps deliver heat at less than half the cost of an electric furnace. During the summer, heat is gathered from the house and rejected to the outside air. During the winter, heat is gathered from outside air and rejected (delivered) to the home. The heating capacity may not meet the home’s heating needs during extreme conditions and supplemental heat is often required.

Ground-source heat pumps:
Ground-source heat pumps work in a fashion similar to air source heat pumps except they transfer heat from or to the ground rather than the air. Two general approaches are used for coupling the heat pump to the ground. The oldest method, referred to as ground-water heat pump (GWHP), pumps water from a well or other water source, transfers heat from the water in the winter and to the water during the summer, and discharges the water back to the ground. The second and newer approach, referred to as ground-loop heat pump (GLHP), buries a long loop of plastic pipe in which a water and glycol mixture is circulated. If the size of the well or loop is undersized, it will not be able to transfer enough heat for the needs.

Hot water boilers:
Hot-water boilers commonly use either baseboard radiation or slab-radiant heating as delivery methods. Baseboard heaters have been used for years and are an adaptation of older cast-iron radiators. Cast-iron radiators needed to be large to provide the surface area needed. Baseboard radiation heaters have fins attached to a pipe to provide the needed area.

Slab radiant heating has gained popularity in the last twenty years. One common approach is to bury plastic or rubber tubing in a concrete slab during the construction process. Hot water from a boiler is circulated through the tubing to warm the floor.

Radiant heating systems are often considered more comfortable than forced-air delivery heating systems. The warm floor heats objects and people in the room, providing a higher sensation of comfort, often at lower air temperatures. Because the room air temperature is often set lower, heating costs are reduced over forced-air heating systems. Another advantage of both baseboard and slab-radiant heating is the ability to heat different rooms to different temperatures.

One of the major disadvantages for hot-water baseboard or radiant heating is a separate air-delivery system is needed if the home is to be air conditioned.


Now, let's talk about the unitary systems.

Unitary systems provide heat to only a portion of a home. These included window or through-the-wall heat pumps, electric baseboard heaters, vented and unvented room heaters, wall furnaces and wood stoves.

Wood stoves:
Three types of stoves are marketed: non-catalytic, catalytic, and pellet. Catalytic stoves contain a ceramic combustor that is coated with a chemical catalyst. The combustor helps assure unburned fuel is combusted prior to leaving the stove. As with all heating systems, it is important to match the stove’s size to the home’s heating needs. Oversized stoves will overheat the home and must be operated in a choked condition, reducing performance and increasing emissions.

Room heaters:
Space heaters are available in both vented and unvented configurations. Vented room heaters burn natural gas or propane and exhaust the products of combustion to the outside. Unvented heaters use room air for combustion and discharge products of combustion back into the room. If unvented heaters are used in a confined space, moisture will build up and potentially cause mold and mildew growth. Other indoor air quality problems may occur when unvented heaters are regularly used for space heating.

Wall furnaces:
Wall furnaces have application similar to room heaters. They are available in both traditional vented and sealed-combustion designs.

Electric baseboard radiation:
Electric baseboard radiation heaters are often used where supplemental heat is needed. Electric baseboards can be controlled room by room so savings are possible by only heating a portion of the home.

Window and through-the-wall heat pumps:
Packaged heat pumps are used a great deal in motels. They provide an excellent supplemental heat source when extending an existing heating system is not possible or if combustion heating is undesirable. Like window air conditioners, noise is a common problem. The compressor is located in the room, as is the distribution fan.

Solar heating:
Active solar energy systems are not commonly cost effective unless energy is expensive. However, use of passive solar heating principles in the design and operation of the home can provide a significant amount of a home’s heating needs.

Passive solar homes do not have to look significantly different than a traditional home. The principles are simple: Admit the sun’s energy into the home when heat is needed; provide a means to store some of the heat for when the sun doesn’t shine; and keep heat out when it is not needed.

To accomplish these simple concepts, a combination of overhangs, glazing, and thermal mass is used. Much of the house’s glass should be located on the southern exposure. Because the sun is to the south and low in the sky during the winter, southfacing glass lets the sun in. Avoid large expanses of east and west glass because they provide very little winter heating benefit but allow lots of heat in during the summer when the sun has moved north.

One important guide to select heating systems is to check their seasonal energy efficiency, also known as the Annual Fuel Utilization Efficiency (AFUE). The higher the AFUE, the more efficient the heating unit. Gas furnaces have a minimum AFUE of 78 % but can be as high as mid 90%. Hot water boilers have a minimum AFUE of 80% with some in the mid 90%. For a general guide, please regard to the second reference website.



Reference website

http://www.energycodes.gov/implement/pdfs/lib_ks_selecting_a_home_heating_system.pdf
http://www.aceee.org/Consumerguide/heating.htm