Some factors to consider when choosing a boiler include the size of the area being heated, the geographical location, and the number of doors and windows. These factors determine the amount of energy output required for the boiler to properly heat each room.
The total amount of energy required, which is measured in BTUs, determines the size of the boiler. Typically, hot climates require only 20 BTUs per square foot. For moderate and cold climates, 35 to 50 BTUs per square foot are adequate.
Another important consideration when choosing a boiler is to select the proper venting system. Power-vent boilers use fans to vent their exhaust fumes. As such, they must be installed in open rooms. A chimney-vented boiler is recommended in cases where the boiler must be installed in a tightly-enclosed area.
Another factor to consider is the boiler’s annual fuel utilization efficiency rating, which measures the boiler’s effectiveness in turning fuel into energy. A higher efficiency rating means that the boiler uses comparatively less fuel than other boilers to produce the same amount of energy, while also decreasing waste gases. Boilers with a rating above 85 percent are considered to be high-efficiency boilers and are usually Energy Star certified.