SECTION 3: C
RITICAL
C
ONSIDERATIONS
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SECTION 3: CRITICAL CONSIDERATIONS
3.1 Basic Information
UHD[X][S] heaters have automatic ignition burners
for ON/OFF operation only.
3.2 Manufactured Units
Gas-fired, power-vented duct furnace with tubular
heat exchanger. Units shall have a minimum of 82%
thermal efficiency. The standard unit shall consist of
a non-separated combustion design with an
aluminized heat exchanger and single stage gas
valve. Design and heat exchanger alternatives shall
be offered as follows:
• Separated Combustion: [S] A separated
combustion unit shall consist of a sealed
enclosure with a hinged door. Combustion air
inlet on rear of heater allows for intake venting
from outside of heated space to be attached.
Combustion flue gasses shall be ducted from
outside the heated space by ductwork
connected to unit’s outlet flange.
• Stainless Steel Heat Exchanger: [X] A stainless
steel heat exchanger unit shall consist of heat
exchanger tubes, heat exchanger tube supports
and heat exchanger tube plates produced of 409
stainless steel. Air inlet temperatures below 40
°F (4.4 °C) are not recommended for this
application.
3.3 Location and Suspension
All models:
• Must be installed indoors.
• Must be installed on the positive pressure side of
the air circulation blower.
• Must be installed in a level position with
horizontal discharge.
• May be mounted on a shelf of non-combustible
material using shelf mounting brackets.
for
details.
• May be suspended from above (
) or from wall brackets of sufficient
strength to support the heater as listed in the
Technical Data Table
.
• Drop rods must be a minimum of 3/8" diameter
mild steel. Four suspension points (3/8" nuts)
are located on top of the heater.
• Must be installed in a manner which allows
access to all serviceable components.
3.4 Minimum Required Installation Clearances
Clearances around the heater and vent must be as
indicated
and
to ensure access for servicing and correct
operation.
3.5 Ventilation
It is important to ensure that there is adequate air
space around the heater to supply air for
combustion, ventilation and distribution in
accordance with local and national codes.
3.6 Gas Supply
It is important that the gas supply pipe is sized
correctly to provide the inlet pressure as stated on
the heater serial plate. The gas supply pipe and
electrical connections must not support any of the
heater's weight.
3.7 Electrical Supply
A permanent 120 V / 1 Ø/ 60 Hz electrical supply is
required for the main electrical power. The heater
also requires suitable controls listed on
3.8 Vent
Choose heater orientation to allow for proper
location of the vent. Each heater must be fitted with
a correctly sized sealed vent system.
If vented horizontally, no other equipment may be
connected to the vent.
