Choosing the right equipment is essential whether you are upgrading the heating system in an existing home or installing one in brand-new construction. If you haven't shopped for furnaces or worked with HVAC contractors before, then several of the terms of the trade may be unfamiliar. When purchasing new equipment, you must consider three vital pieces of terminology: load, capacity, and efficiency. Although each of these characteristics is independent, balancing all three is a critical part of putting together a long-lasting and efficient heating system.
The Starting Point: System Load
In an HVAC system's design, the load is the amount of work that is required to keep your home comfortable. For a heating system, you can think of this as how cold your home will typically get. Two primary factors influence this value: interior volume and region. Colder temperatures obviously require any heating system to work harder, while larger interior volumes require more energy to heat. In most cases, you can use a simple formula to calculate your total heating load based on your home's location and square footage. This value can help to provide you with a ballpark estimate of your new furnace's size, but an in-depth audit by a trained HVAC professional is necessary for a more exact calculation.
Meeting Demand: Furnace Capacity
If you think of your home's heating load as the demand side of an equation, then the furnace's output capacity is the supply side. Furnaces, like most heating and cooling appliances, measure their capacity in British Thermal Units (BTUs). For ease of comparison, load calculations generally produce a number in BTUs, as well. Properly sizing your new furnace is a matter of selecting a unit with sufficient capacity to meet your calculated load. Note that straying too far from this value can result in a highly inefficient system in both directions. Oversized furnaces may short-cycle more often, while undersized furnaces will run continuously.
Getting There In Style: Efficiency
Keeping your home warm is a simple matter of matching furnace output and heating demand, but there's still more to consider. Modern furnace efficiency ratings indicate the percent of fuel converted into useful heat, with the remainder of the fuel's energy lost to exhaust gases. Most furnaces will keep your home equally warm (assuming they meet your load requirements), but they may get there with drastically different amounts of fuel. With a standard-efficiency furnace, a portion of your fuel costs is wasted money. With high-efficiency models, less of your fuel costs are lost to the environment as waste heat.
Keeping all three of these characteristics in mind is essential to choosing a furnace that will keep your home warm efficiently and reliably.
To learn more, contact a furnace installation contractor.