It’s time to buy a new furnace. You thought it would be a relatively straightforward task, but you’re feeling a bit overwhelmed. What does your heating professional mean by all this talk about burners and fans?
Because the furnace’s burners and fans affect so many things — including the comfort of your home, the cost of the furnace, and the furnace’s operating efficiency — it’s important to understand what options are available to you. Here are some of the most common questions ATCO EnergySense is asked about burners and fans.
Different types of furnace burners operate with different degrees of flexibility.
Single-stage burners have no flexibility. The burner is either on or off. Older conventional, mid-efficiency and some high-efficiency furnaces have single-stage burners. You will have more difficulty efficiently maintaining a consistent, comfortable temperature in the house because the burner is either on or off.
Two-stage burners provide more flexibility than single-stage burners. When your home does not require a great deal of heat, the burners operate at a low level. When it gets colder, the “second stage” is activated and the burner runs at full capacity. This system operates more efficiently than a single-stage burner, offering increased energy savings. As well, two-stage burners provide a more consistent, even temperature.
Three-stage and modulating burners have the most flexibility. These systems gradually increase and decrease their operation to meet the home's heating demand, instead of abruptly cycling between on and off. Warm air circulates throughout your home for longer periods of time, with less natural gas being used to achieve more consistent temperatures. This system is the most efficient.
Furnace fans move heat through the heating ducts in your home. Most high-efficiency furnaces are equipped with a variable speed fan, although single-speed and two-speed fans can still be found.
Single-speed fans deliver heat at a single constant speed, whether the fan is set to run continuously or when there is a call for heat.
Two-speed fans run at either low or high speed. When there is no call for heat and the fan is set on continuous, it operates at a moderate speed to keep warm air circulating through the home. When there is a call for heat, the fan runs at a higher speed to bring the house to a comfortable temperature more quickly.
Variable speed fans, also known as Electronically Commutated Motor (ECM) or direct current (D/C) fans, operate at varying speeds to meet the home’s heating needs. The varying speed eliminates temperature swings and uncomfortable drafts. When set to run continuously, a variable speed fan circulates air through your home more efficiently, reducing electricity costs.
Running a furnace fan continuously ensures more uniform temperatures throughout your home. However, you need to be aware of a few things.
• AC motors (which are common in single- and two-speed fans) use considerably more electricity than variable speed (DC) motors. Read more in the Managing Electricity at Home ( PDF 2.1 MB) publication.
• You may draw in too much fresh air through the duct when running the fan continuously. This causes the furnace to trigger a call for heat that might otherwise not be needed. This can be resolved by putting in an electromechanical damper on the fresh-air duct.
More information on purchasing a high efficiency natural gas furnace can be found on our Energy Fact Sheets.
Any steps you take to make your home draft free will reduce heating requirements—and therefore reduce heating costs.
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