OHP Installation Manual

1918
OHP Series
2.0 Installation • Ventilation
Ventilation
This infrared heater must be vented in accordance with national, state, provincial and local codes, and the
guidelines in this manual. Refer to the latest edition of the ANSI Z223.1 (NFPA 54) Standard.
It is required that the upper levels of the space to be heated are properly ventilated to supply combustion air
to the heaters and to sufficiently dilute the products of combustion. It is also important to keep the flue
discharge area clear of gas piping and electrical wiring (see Figure 2.9).
Provisions must also be made to provide sufficient fresh air intake area and exhaust air outlet area. Natural
or mechanical means shall be provided to supply and exhaust at least 4 CFM/1,000 BTU/h of total gas input
of heaters installed. Exhaust openings for the removal of flue products must be above the level of the
heater(s).
Where insufficient air movement exists, induced air displacement is required. A balanced system is essential
to avoid negative building pressure which causes excessive infiltration, unfavorable drafts, and affects
combustion efficiency.
Air displacement may be accomplished by either gravity or mechanical means. Mechanical exhausters are
preferred and typically mounted at high points on the roof over where stagnant air accumulates inside. For
a flat roof, considerations of prevailing winds, high and low pressure areas, and distribution of air movement
must be taken into consideration when locating exhausters.
Best air distribution is accomplished by using a number of small exhausters versus one large exhauster.
Provide a minimum of one square inch of inlet area per 1,000 BTU/h for combustion air supply. Inlet opening
in the building should be well distributed, located high on the wall and should direct incoming air upward to
dilute products of combustion while preventing drafts at lower levels. Inlets are typically 1 to 3 sq. ft.
In certain applications, local codes may require that mechanical exhaust systems be interlocked with the
heaters to enable both to function simultaneously or allow control of exhausters with a ceiling mounted
humidistat.
Figure 2.9 • Hot Flue Discharge
WARNING
!
Improper or insufficient ventilation may result in explosion, fire, health problems,
carbon monoxide poisoning, or death. Vent enclosed spaces and buildings
according to national, state, provincial, and local codes.
Discharge released from side
air channels. Keep area clear of
gas piping and electrical wiring.