Two types of units cool an entire house: a central air conditioner or a heat pump. If you only need to cool a specific area, a window air conditioning unit could be your most energy-conserving choice. Regardless of what type you are considering, remember that models will vary in efficiency ratings and efficiency has a direct impact on operating costs, so optimizing efficiency should be a priority. Consider buying an ENERGY STAR®-qualified model.
If you decide you want to cool your entire house, you should consider which system to install - central air conditioning or a heat pump - when reviewing your home's heating needs. Chapter 5 describes how a heat pump both heats and cools. An air conditioner is actually a heat pump that can only cool. Remember: your heating decisions can affect your cooling options.
Duct Work for Central Air
Duct work is generally needed to carry cool air throughout the house in a central air conditioning system. If you have a forced air heating system, as shown, you can usually use the same ducts for cooling. If you do not have duct work, you can look into installing it or consider air conditioning technologies that have been developed for homes without ducts. These alternatives are more costly, so if you are considering them, investigate your options with your heating/cooling contractor.
Mini splits are systems suited to homes without a central air-distributed system. No duct work is required. The system consists of two components: an outdoor condensing unit, and an indoor evaporator and fan. The indoor section can frequently be mounted on any interior or exterior wall, and is much quieter than a window unit.
Window air conditioners are effective if you only need to cool a specific area of your home - say, a bedroom or a kitchen. And they will cost less to install than a central air conditioning system. If you don't have duct work, they might be your most practical choice. It is important to match the capacity of the window air conditioner with the size of the area to be cooled. Window units should either be covered in winter or, better still, removed to minimize heat loss.
A Word About… Fluorocarbon Refrigerants
Air conditioners (home and auto), heat pumps and most freezers and refrigerators rely on the compression and expansion of fluorocarbon refrigerants to produce their cooling effect. Remember, heat pumps are reversible air conditioners, so they use the same fluids.
The refrigerants include CFCs (chlorofluorocarbons), HCFCs (hydro chlorofluorocarbons) and HFCs (hydrofluorocarbons). These substances can damage the environment if they leak or escape from air conditioners.
CFCs are a major contributor to the thinning of the ozone layer and are no longer produced in North America. HCFCs, while their effect is less drastic than those of CFCs, still contribute to the thinning of the ozone layer, and are being phased out. HFCs are not known to damage the ozone layer but are greenhouse gases which cause global warming.
It is illegal in Ontario to allow these chemicals to escape and damage the environment. By law, in Ontario only technicians holding a valid Ozone Depletion Prevention (ODP) card issued by the Ministry of the Environment may work with these refrigerants, including when refrigerant is added to or removed from any equipment. When any appliance or equipment containing such refrigerants is retired from service, the refrigerant must be properly removed by an ODP card-holding technician.
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