Residential furnaces come in various sizes measured in Btu (British thermal units). They range from 40,000 Btu all the way up to 100,000 Btu or even larger. Your furnace needs to be correctly sized to provide efficient heating and cooling and avoid excessive repairs. A furnace sized too small will not deliver, or it will strain to deliver enough heating and cooling to your home, while an oversized furnace will waste energy and money. Both will lead to excessive breakdowns and premature failure.
When we get called to a home with heating and/or cooling problems, one of the most common issues we confront is a furnace that’s improperly sized. For the most part it comes from either laziness or lack of knowledge by the person who installed or replaced the furnace.
Our field is filled with people who should know better, but who persist in using “rules of thumb” when it comes to selecting a furnace size. They will base it solely on the square footage of a home, or when replacing a unit will simply select the same size as the old one.
Common sense tells us that bigger homes probably will require larger furnaces, but a lot more goes into selecting the proper size for any given amount of space. Proper size should be based on energy-loss calculations that take into account window areas, the amount of insulation and other factors. This evaluation needs to be done room by room. Professional companies like ours used tried-and-true manuals and computer programs to guide us through the calculations. It’s not that hard to do and we’re always mystified why so many HVAC firms choose to shortcut the process when it requires so little effort, yet has so much to do with how the system performs.
Energy-loss calculations need to be done when replacing a furnace, as well as when installing a new one. One simple reason is that the old equipment might have been improperly sized, which might well be the reason it broke down. Even if the old furnace was right for the job, replacing older units with new high-efficiency models often enables you to downsize to a unit that can do more with less and save you energy and money in the process.
Also, with any furnace installation or replacement, it’s important for the technician to check the ductwork to make sure it is appropriately sized and not plagued by leakage. Your furnace is the heart of your home’s HVAC system, while the ductwork is its arteries. You know what happens to your heart if your arteries get clogged or get diseased.
No doubt you’ve heard the old adage – “you get what you pay for.” People who shop for the cheapest price when selecting an HVAC company will most likely end up with someone who cuts corners. One way to cut corners is to use a “rule of thumb” instead of energy-loss calculation when selecting or replacing a furnace. Applewood never cuts corners.