A(n) ___ is a common type of heat exchanger used to heat the air in a building space.

Cold makeup water reduces overall boiler efficiency because energy is required to ___ the water.

Air flow in a natural draft system is controlled as necessary through the ___.

Low-water cutoffs must be checked at least weekly or when local ordinances require.

Low-water cutoffs must be checked at least weekly or when local ordinances require.

___ heat must be added or removed to cause a substance to change state between a solid and a liquid or a liquid and a gas.

___ heat must be added or removed to cause a substance to change state between a solid and a liquid or a liquid and a gas.

Low-water cutoffs must be checked at least weekly or when local ordinances require.

The ASME Boiler and Pressure Vessel Code requires each automatically fired steam boiler to be protected from overpressure by ___ pressure-actuated control(s).

The ___ is a nongovernmental international organization that is comprised of national standards institutions of over 90 countries.