15 May 2003
CHAPTER 3 SYSTEMS
SYSTEM SELECTION. The following determines eligibility of a facility for air
conditioning, dehumidification, evaporative cooling, mechanical ventilation, or heating.
HEATING SYSTEMS. Use steam or high-temperature water for large
Steam. Do not use single-pipe systems. For safety purposes, use low-
pressure steam (15 psig [100 kPa gage] and below) where terminal equipment is
installed in occupied areas. High-pressure steam (above 15 psig [100 kPa gage]) unit
heaters may be used for space heating in areas such as garages, warehouses, and
hangars where the discharge outlets are a minimum of 13 feet (4 meters) above floor
Do not use gravity flow hot-water systems.
3-2.2.2 For safety purposes, use low-temperature hot water (250 degrees F [120
degrees C] and below) where terminal equipment is installed in occupied areas.
Medium-temperature hot water (350 to 420 degrees F [120 to 175 degrees C]) or high-
temperature hot water (350 to 400 degrees F [175 to 200 degrees C]) unit heaters may
be used for space heating in areas such as garages, warehouses, and hangars where
the discharge outlets are a minimum of 13 feet (4 meters) above floor level.
3-2.2.3 Freeze protection will be automatically provided by operating circulating
pumps when outside temperature drops below 35 degrees F (2 degrees C) or will be
provided by the addition of an appropriate antifreeze solution.
Warm Air. Do not use gravity flow warm air furnaces. Direct-fired heaters
are prohibited in areas subject to hazardous concentrations of flammable gas, vapors,
Infrared Radiant Heating
. Consider infrared radiant heating for high-bay
areas or where spot heating is required. Gas, oil, and electricity may be considered as
fuel sources. Use night setback where it is both appropriate and cost effective.
Electric Resistance Heating.
Do not use electric resistance heating except
where permitted in the following circumstances:
3-2.5.1 Family Housing. Electric resistance heating may be used where a bathroom
has been added and the existing heating system is inadequate to heat the addition, or
where a bathroom has been added and it is unreasonable from an engineering or
economic position to extend the existing heating system to the new area. Provide an
occupant-activated time switch with a maximum time setting of 30 minutes for electric
maximum setting of 75 degrees F (24 degrees C) throughout the housing project.