Choose the right-sized furnace for your home.
Choosing the right-sized gas furnace depends on the size of your home and how much heat it loses through its windows, walls, doors and roof. If a furnace is too small, it will run constantly to keep up with demand. If it's too large, it will turn on and off constantly, shortening the life of the furnace's parts. An HVAC contractor can calculate the British Thermal Units (BTUs) necessary to heat your home, but you can also calculate the correct furnace size yourself. Does this Spark an idea?
Instructions
1. Find the gas furnace's efficiency rating percentage. This is located in the manual and on the sticker attached to the furnace. Multiply this percentage by the furnace's BTU capacity, which is also listed on the label. For example, if the efficiency rating is 90 percent and the furnace is a 100,000 BTU unit, then your total is 90,000 BTUs.
2. Compare the BTUs you've calculated to the charts available from the manufacturer. The charts are a guide to how many BTUs you'll need to heat the number of rooms in your house. If the number you've calculated is too low, you'll need a slightly larger furnace. If it's too high, you'll need a smaller one.
3. Go online to make a more specific calculation that takes into account the average winter temperature, number of heating days, size and type of windows and the insulation in your roof and walls. The Energy Star website has an online calculator that will give you a closer estimate of the furnace size needed --- see the Resources section for a link that allows you to download the form.
Tags: your home, efficiency rating, furnace size, right-sized furnace
