Addison UHAS 150, Installation, Operation & Service Manual

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SECTION 3: C
RITICAL
C
ONSIDERATIONS
5 of 59
SECTION 3: CRITICAL CONSIDERATIONS
3.1 Basic Information
UHA[T][X][S] heaters have automatic ignition
burners for ON/OFF or HIGH/LOW operation only.
3.2 Manufactured Units
Gas-fired, power-vented unit heater 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] For Models 150-250,
a separated combustion unit shall consist of a
sealed hinged enclosure. Combustion air inlet
on rear of heater allows for vent from outside
heated space to be attached. For Models 300-
400, a seperated combustion unit shall feature
an enclosed, sealed burner box. A piece of
flexible air duct connects this burner box to a
flange on the cabinet. Combustion air shall be
ducted from outside the heated space, with the
ductwork connecting to the unit with the use of
the 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 plate produced of 409
stainless steel.
The use of stainless steel heat exchanger unit is
recommended when air inlet temperatures are
below 40° F (4.4° C) or temperature rise is less
than 40° F (22.2° C) as condensation may form
on the heat exchanger resulting in corriosion that
may shorten its life.
• Two Stage Gas Valve: [T] A two-stage gas valve
shall allow heater to function in HIGH/LOW
operation.
3.3 Location and Suspension
All models:
• Must be installed indoors.
• Must be installed in a level position with
horizontal discharge.
• May be mounted on a shelf of non-combustible
material.
• May be suspended from above ( See Page 10,
Figure 4 ) or from wall brackets of sufficient
strength to support the heater as listed in the
Technical Data Table on Page 57, Section 16.2
and Page 59, Section 16.5 .
• 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
on Page 7, Figure 3 and Page 11, Section
7 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
on Page
11, Section 7 .
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.
See Page 19, Section 9 .
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 in accordance with
See Page 21, Section 10 .
3.8 Vent
Choose heater orientation to allow for the proper
location of the vent. Each heater must be fitted with
a correctly sized sealed vent system.
If vented horizontally, no other appliance may be
connected to the vent.
See Page 11, Section 7 .