Solid fuel units burn continuously, not
intermittently as do oil or gas units. For this
reason, particular attention should be paid to
the safety control features of the unit. On boilers,
pressure-temperature relief valves control draft
when water jacket temperature exceeds a set
limit, and a circulating pump control allows
water to circulate through the piping if the boiler
overheats. On furnaces, besides the damper control,
a blower is wired to operate continuously when
the duct temperature exceeds 250°F. A furnace or
boiler should be installed by a qualified installer
in accordance with National Fire Protection
Association standards, state codes, and the
manufacturer’s recommendations. In most states,
installation requirements are specified by the state
building code and a permit is needed.