Boiler Size for Hydronic Heating

Hydronic Heating Systems

• In hydronic heating systems water from your plumbing system flows into the boiler where it heats. The hot water then flows through piping into every room of your home via a convector. The hot water flows through the convector and gradually warms up the room. The spent water returns to the boiler through a separate set of return pipes. A related version of this system heats the water to boiling in the boiler, creating steam. The steam follows pipes through your home to radiators. Once the steam cools, it condenses to water and returns to the boiler through the same pipes.

Boilers for Heating

• Boilers can use natural gas, oil or electricity to heat the water. The temperature a boiler heats the water to depends on whether you have a steam or a water system. Water system boilers only heat the water to 170 to 180 degrees Fahrenheit, as opposed to the 212 degrees Fahrenheit required to boil water for a steam system.

Why The Right Size Matters

• Bigger is not necessarily better when it comes to boilers. Too large a boiler for your home can cause energy loss. The boiler fires more often than it needs to when it is too large, wasting energy and driving up your electric bills.

Sizing Boilers

• Boiler sizes for a home are calculated by the number of square feet being heated. The size of the boiler refers not to the physical size but to the amount of heat the boiler generates in a measure called British thermal units. According to "Steam and Hot Water Primer," by Chris Langley, boiler size for a home is generally 50 BTUs per square foot, but this number depends on the location of the house. Homes in warmer climates need fewer BTUs per square foot, but people in colder regions can require a more powerful boiler.