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Enerco | enerRadiant® HST Series Heater
Operating Instructions and Owner’s Manual
Non-Pressurized Outside Air Supply Duct
Outside Combustion Air Supply
The Ener-Radiant HST heater is approved for installation with an
outside air supply system. Some compounds such as halogenated
hydrocarbons or other corrosive chemicals in the air can be drawn
into the equipment and cause an accelerated rate of corrosion of
some of the heater components. The use of such chemical
compounds near the enclosure should be avoided.
IMPORTANT:
If the building has a slight negative pressure or
contaminants are present in the air, an outside combustion air
supply to the heaters is strongly recommended.
For an outside air supply a three (3") inch O.D. single wall pipe may
be attached to the heater. The duct may be up to twenty five (25')
feet maximum length or two (2') feet minimum length with no
more than two (2) elbows.
The air supply duct may have to be insulated to prevent
condensation on the outer surface. The outside air terminal should
be securely fastened to the outside wall by drilling four (4) holes in
the outside flange; wood screws or bolts and expansion sleeves
may be used to fasten terminal.
VERTICAL THROUGH THE ROOF
Intake Vent
3" Starting Collar
¼” per ft.
downwards
6" Min.
3" Dia.
Single-Wall Pipe
Flashing
3' Min.
Vent Cap
(Leslie VersaCap)
Vertical Venting
Air For Combustion (Residential)
If indoor combustion air is to be supplied for a tightly enclosed
area, one square inch of free area opening shall be provided below
the heater for each 1,000 Btu/hr of heater input.
When outside air is used, the opening below the heater shall be
one square inch of free area for each 4,000 Btu/hr of heater input.
In contaminated atmospheres or high humidity areas, optional
outside air for combustion is recommended.
Adequate clearances around the perforated fresh air plate must be
maintained at all times. In larger open areas of buildings,
infiltration normally is adequate to provide air for combustion.
Direct Outside Air For Combustion (Residential)
Outside combustion air should be supplied directly to the heater
when the building is subject to negative pressure or contaminants
are present in the building air. These contaminates include paints,
solvents, corrosive vapors or any other foreign particles that may
cause damage to the heater or result in poor combustion.
Outside combustion air can be brought directly to the heater by a 3
inch diameter duct less than 25 feet long or equivalent. This is
attached to a 3 inch starting collar that is fitted to the top of the
control cabinet after first removing and discarding the perforated
cover. An approved vent cap must be placed directly to the end of
the outside combustion air inlet pipe. The combustion air inlet
should be a minimum of 3 feet, either vertically or horizontally,
from the flue vent termination. The air intake terminal must be
located not less than one foot above grade. It is good installation
practice to supply combustion air from the same pressure zone as
the vent outlet.
In colder climates, where necessary, insulate the fresh air duct.
Avoid locating the fresh air duct directly above the control box.
Provide a capped cleanout T as necessary.
