When you have a furnace replacement looming, the most important step is finding a contractor who will conduct a load calculation to find the precise size heating system for you home. A contractor who simply goes by the size of your existing furnace, or uses a discredited “rule of thumb” sizing method, is taking a shortcut that can cost you long-term in higher energy bills, repairs and premature replacement. The load calculation takes into account a constellation of factors about your home and lifestyle that dictate the size of the system you need.
Contractors use computer software called Manuals J, S and D when sizing a new furnace and ensuring compatible ductwork. The most important calculation, Manual J, considers these factors in order to determine your home’s heating load:
- Cubic footage you need to heat;
- Insulation levels throughout the structure;
- Number of windows, their energy efficiency and orientation to the sun;
- Rate of air infiltration and the direction your home faces;
- Floorplan design;
- Number of home occupants and ages;
- Preferred indoor temperatures;
- Appliances you use that create heat; and
- Landscaping factors.
The contractor will use Manual S to analyze the suitability of different furnaces for your home. The last step is the ductwork analysis with Manual D that gives the contractor information about the capacity and configuration of the ductwork so it will work with your new furnace.
It’s important to go through these analyses because a system that’s too small won’t be able to heat your home comfortably when it’s especially cold, and one that’s too large will run in short cycles. Short cycling drives up energy costs, increases wear on the system, and won’t keep you as comfortable. It runs in brief cycles that won’t heat your home evenly. The air in rooms farther from the blower won’t have time to pass through the system long enough to be thoroughly heated.
A furnace is a long-term investment. Taking the time to go through each step of the sizing process assures your comfort and satisfaction. To learn more about a furnace replacement, please contact us at Ace Hardware Home Services. We’ve provided outstanding HVAC services for Dayton area homeowners since 1978.
Our goal is to help educate our customers in Dayton, Ohio about energy and home comfort issues (specific to HVAC systems). For more information, download our free Home Comfort Resource guide.
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