A system boiler heats water and pumps it into a holding tank connected to the household water lines and central heating system. System boilers deliver hot water to multiple faucets simultaneously and at moderate pressure.
System boiler installation is quick and simple because each boiler contains many heating and water delivery components that would otherwise require separate installation, according to Swale Heating.
Other common types of boilers include open vent boilers and combination condensing boilers. Open vent boilers have multiple storage tanks, including a general tank and one or more attic expansion tanks. The elevated tanks boost water pressure, but take up considerable space.
Combination condensing boilers have no storage tank. This type of boiler heats water as it flows into the heating unit and immediately delivers the water to a faucet or the radiator system. Combination condensing boilers provide instant hot water, but have limited output capacity. These space-saving boilers are only capable of supplying water to one faucet at a time.
Another type of boiler is the high-efficiency condensing boiler. Boilers in this category use heat exchangers to recycle heat that would otherwise dissipate through the exhaust pipe. Consequently, high-efficiency condensing boilers consume less fuel than other models.