A relatively new innovation in home heating, the two-stage furnace, is making an appearance around the country. These appliances deliver on-paper energy savings, but their real-world performance is largely determined by climate. A little research is needed to determine whether a two-stage furnace is a good idea in the Twin Cities.
Definition
The most common furnaces are one-stage models. Their burners have a single “On” setting: full blast. Typically, 
that basic on/off choice is mirrored at the air handler; it also has only one operational speed.
Two-stage furnaces have dual burner settings, “low-fire” and “high-fire,” twinned to a variable-speed blower motor (the machine adjusts its speed automatically). The low-fire setting, and minimal blower rotation, is employed in most weather conditions. Both measures result in reduced energy usage. If temperatures plummet, however, high-fire performance and increased air handler speed take over.
Great for Cold Locations
Two-stage furnaces are ideal for cold-winter climates, and the reason why is another two-parter:
- First, wild temperature swings increase fuel usage because your furnace must struggle to compensate for the sudden drops.
- This causes a second costly effect; machinery that starts and stops frequently wears out more quickly.
A two-stage furnace that can maintain comfortable indoor temperatures – in most conditions – on its low setting, then ramp up to high-fire when the weather demands, addresses both issues.
In East-Central Minnesota
Here in Minneapolis-St Paul, we have the coldest average winter temperature of any major city in America. A furnace that can perform effectively for much of the year at a fraction of its maximum potential, then deal with drastic cold snaps, should deliver substantial fuel savings.
Two-stage furnaces, however, are more complex appliances than conventional furnaces, so are typically more costly to buy. While the purchase and installation may cost a bit more money, the monthly energy savings can be considerable. Such decisions should be based on all available information.
Marsh Heating & Air Conditioning provides 24/7 service to the entire Twin Cities Metro area; please contact us to learn more, or to schedule a free in-home consultation.
Our goal is to help educate our customers in Minneapolis-St. Paul, Minnesota about energy and home comfort issues (specific to HVAC systems). For more information about two-stage furnaces and other HVAC topics, download our free Home Comfort Resource guide.
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