WHY INVEST IN A 2-STAGE FURNACE? This is one of the most frequently asked questions to an HVAC professional, which is not surprising given the many misconceptions that are out there. The main advantage to the two stage furnace is the improved home comfort that is achieved through the reduced indoor temperature fluctuations that the 2-stage furnace delivers, NOT increased efficiency (a 90% furnace is 90% efficient, regardless of how many stages it runs in).
The reduced indoor temperature fluctuations on a 2-stage furnace are accomplished through a gas valve that has both a low-fire and a high-fire position, and the multi-speed/variable-speed blower motor. The 2-stage furnace is especially appropriate in climates such as that of Chicago where a “winter day” can be defined as anything from +40 degrees down to -40 degrees. Obviously, it is much easier to heat your home when it is +40 than when it is -40, although you have to use the same system to heat your home on both days.
A single stage furnace, with a fixed gas valve and a blower motor that runs on only one speed will cycle on and off continuously during periods of mild weather (+40). Not only does this type of start-stop-start-stop operation put an extreme amount of stress on the system, but the space that the system is trying to heat will be in temperature fluctuation.
The 2-stage furnace, on the other hand, will operate in its low-fire stage during periods of mild weather (pushing less air through the ducts and less combustion gas through the flue), and automatically ramp up to its second high-fire stage during extremely colder weather. This will cause the home to experience fewer and much less severe temperature swings in the home, which will result in greater over-all comfort for you and energy savings. In addition, your system can be expected to last longer since it is not being continually shut on and off (which, in the case of the single stage furnace, inevitably leads to motor seizure and failure or other furnace repairs).
Other Related articles
- HVAC for Beginners- How A Furnace Works| Lynwood, Glenwood
- 2010 Energy Tax Credits| Addison, Palos Park, Lockport
- Fix My Furnace| Lockport, Mokena, Woodridge
- A Top of the Line Furnace| Downers Grove, Hinsdale, Alsip
- Dispelling the Misconceptions| Streamwood, Markham, Hoffman Estates