How Small a Space Can a Hot Water Boiler Fit?

Conventional vs. Combination Boilers

• Conventional boilers feature gas-fired jets that heat an iron heat exchanger. The water becomes hot as it flows over the heat exchanger. Also known as a storage water heater, conventional boilers are larger than other types because they require a 20- to 80-gallon tank for storing water. Conventional boilers are primarily for space heating. Combination boilers provide space heating and instant hot tap water through its heating coils. Running water from the house's plumbing system passes through the coils, making it unnecessary for combination boilers to have water tanks. As a result, combination boilers do not need as much space as conventional boilers and are easier to install.

Fuel-fired vs. Electric

• Whether a boiler is fuel-fired or electric also determines how small a space a water boiler fits. Fuel-fired boilers have certain space requirements because they emit gases. These type of boilers cannot be installed in small spaces or rooms with flammable objects such as aerosol cans, paint thinners or gasoline. Homeowners with electric boilers have more options for places to install their boilers because they do not have to worry about gases. Electric boilers also have higher annual fuel utilization efficiency (AFLUE) ratings. Fuel-fired or electric boilers are either conventional or combination units.

Storage Closets

• According to East Carolina University, a confined space is an area large enough for someone to work, such as installing a hot water boiler, but also has restricted means of entering or exiting the space. Also, confined spaces are not meant for homeowners to work in for long time periods. A prime example of a confined space within a house is a storage closet. Natural gas and oil-fired boilers should not be installed in a storage closet because they emit noxious fumes. A confined space is any area with less than 50 cubic feet of space per 1,000 British thermal units per hour emitted from the boiler.

Attics

• Proper access opening, passageways and working space are needed when installing a water boiler in an attic. The International Association of Certified Home Inspectors recommends an access opening of at least 20 inches wide by 30 inches long, which allows the removal of the appliance. The association also suggests a passageway of 30 inches tall and 22 inches wide, but no longer than 24 feet. The work space surrounding the boiler should be 30 inches deep and 30 inches wide; the work space needs to be located on the appliance's service side.