The top three things to look for when purchasing a boiler are size, efficiency and venting requirements. Buying a new boiler can lead to significant savings on one's energy bill if the old boiler is more than a decade old. Older boilers tend to be oversized for their homes.
Boiler capacity appears on product details in BTUs, or British Thermal Units. Each BTU is the amount of energy it would take to elevate the temperature of one pound of water by one degree Fahrenheit. Every structure has its own BTU requirement based on climate, location, amount and quality of insulation, and the number of doors and openings. A home heating expert can estimate the BTUs that a home requires.
Boilers also have an annual fuel utilization efficiency rating, which shows the success the unit has at changing fuel into heat energy. Boilers with a rating of at last 85 percent are considered high-efficiency. Most oil furnaces carry AFUE ratings between 80 and 90 percent, while gas furnaces range between 89 and 98 percent. Electric boilers get close to 100 percent because they do not make waste gas, which makes them a good choice in places where electricity prices are relatively low.
Choosing the right venting system for the home is important as well. Direct- and power-vent boilers send exhaust through a side wall vent, while chimney-vented boilers send exhaust out through the chimney. Choosing the right boiler may not be a purely DIY decision, so consulting a heating professional can end up saving money over time.