The size of boiler system that you need for your house depends on the size of your doors, windows, insulation, and kind of weather that you have for outdoor design temperature. In selecting the right boiler, get one that fits the needs of your home. If you buy a small boiler, it may not be able to provide you with sufficient heat. Chances are, you’ll have to run it constantly to catch up with your needs.

If you buy one that is too large, you may be short of budget, and wasting energy. The best thing to do is calculate the area of your house per square foot to get the appropriate size of the boiler that you need. If you have a 3,000 sq ft house, with 3 occupants or less, and all of them take showers at the same time, you need a 30-gallon boiler. If you have 4 to 7 occupants, a 40-gallon unit will do.

How to determine the size of your boiler system:

• Measure each room in your house according to square footage.
• Each wall length should be converted to inches. If the length of your room measures 10 feet by 8 feet on one side, and 3 inches on the other side, multiply 10 ft by 12, since one foot has 12 inches, in order to get 120 inches. Then, multiply 8 ft by 12 inches and add 3 to get a total of 99 inches. To get the square inches of each room, multiply 99 by 120 to get a total of 11,880 sq inches.
• Convert your measurement from sq inches to sq feet to get the size of your boiler system. Divide the sum of sq inches by 144, to get the number of sq feet. If the total is 158,950 sq inches, therefore, the area of your house is 1,103.819 sq feet.
• To meet the heat required for this area, determine the required number of Btu or British thermal units. Your heater should have the capacity to produce around 50 Btu per sq foot. Multiply your area of 1,103 sq feet by 50 to get the right size of your boiler.

You will notice that it’s not easy to calculate the size of the boiler system that you need, so, it’s recommended to ask the help of a professional that offers flat rate on materials and labor to make everything perfect.