Before you invest in a new heating system, make sure that your HVAC contractor commits to do the furnace sizing carefully. Failing to do so could land you with a system that’s the wrong size. Considering how long winters last in Minnesota, a properly sized furnace will perform better, lower energy bills and have a longer life span than one that’s the wrong size.
Going by the BTUs (British thermal units) of your current system can be misleading because of any energy-efficiency improvements you or a prior homeowner has made to the home since the original furnace was installed. Instead the HVAC contractor should use industry standard software Manual J to find the size of the furnace you need based on your ho
me’s heating load, which consists of these factors and others:
- Size and energy efficiency of your home
- Heat generated indoors
- Floorplan design
- Personal comfort preferences
- Window location and orientation
Once the contractor has determined your home’s heating load and the size of furnace that will handle it, he or she moves onto the next steps, which involve sizing and configuring the ductwork, and verifying that the system you’ve chosen is the best system for your home and heating conditions.
Conducting the load calculation avoids these problems:
- Higher energy bills. The energy heating systems use at start-up is the highest, and as a result the frequent start-ups with oversized equipment increase energy costs.
- Shorter system life. Those frequent start-ups increase the wear on all the components inside the furnace, wearing it out faster. A system that’s too large may also rust faster, since the flue and heat exchanger don’t become as hot.
- Lower indoor comfort. The air in your home won’t have as much time to pass through the blower, and you may have problem areas that don’t get warm enough.
- Reduced indoor air quality (IAQ). The shorter running cycle won’t remove as many airborne particulates, compromising IAQ.
The major issue associated with choosing too small a furnace is that it won’t be able to heat your home adequately during our coldest weather.
To learn more about why furnace sizing is so critical, please contact us at Marsh Heating & Air Conditioning, providing outstanding HVAC services for Twin Cities homeowners since 1974.
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 furnace sizing and other HVAC topics, download our free Home Comfort Resource guide.
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