13
3.
These units are designed for either natural or propane
(LP) gas and are specifically constructed at the factory for
only one of these fuels. The fuels are NOT interchangeable.
However, the furnace can be converted in the field from
natural gas to LP gas with the appropriate factory kit (see
unit Technical Manual for the appropriate kit). Only a
qualified contractor, experienced with natural and propane
gas systems, should attempt conversion. Kit instructions
must be followed closely to assure safe and reliable unit
operation.
4. With all units on a common line operating under full fire,
natural gas main supply pressure should be adjusted to
approximately 7.0” w.c., measured at the unit gas valve.
If the gas pressure at the unit is greater than 10.5” w.c.,
the contractor must furnish and install an external type
positive shut off service pressure regulator. The unit will
not function satisfactorily if supply gas pressure is less than
5.5” w.c. or greater than 10.5” w.c..
NOTE:
A minimum horizontal distance of 48” between
the regulator and the furnace flue discharge is required.
5. With all units on a common line operating under full LP
gas main supply pressure should be at least 11.0” w.c. and
must be no greater than 14.0” w.c., measured at the unit
gas valve. Unit will not function satisfactorily if supply gas
pressure is less than 11.0” w.c. or greater than 14.0” w.c..
6. All pipe connections should be sealed with a pipe thread
compound, which is resistant to the fuel used with the
furnace. A soapy water solution should be used to check
all joints for leaks. A 1/8” NPT plugged tap is located on the
entering side of the gas valve for test gauge connection to
measure supply (main) gas pressure. Another 1/8” tap is
provided on the side of the manifold for checking manifold
pressure.
T
HIS
UNIT
AND
ITS
INDIVIDUAL
SHUTOFF
VALVE
MUST
BE
DISCONNECTED
FROM
THE
GAS
SUPPLY
SYSTEM
DURING
ANY
PRESSURE
TESTING
OF
THAT
SYSTEM
AT
TEST
PRESSURES
IN
EXCESS
OF
1/2 PSIG (13.8”
W
.
C
.).
WARNING
T
HIS
UNIT
MUST
BE
ISOLATED
FROM
THE
GAS
SUPPLY
PIPING
SYSTEM
BY
CLOSING
ITS
INDIVIDUAL
MANUAL
SHUTOFF
VALVE
DURING
ANY
PRESSURE
TESTING
EQUAL
TO
OR
LESS
THAN
1/2 PSIG.
CAUTION
7. There must be no obstruction to prevent the flow of
combustion and ventilating air. A vent stack is not required
and must never be used. The power ventor will supply
an adequate amount of combustion air as long as the air
passageways are kept free of any obstructions and the
recommended external unit clearances are maintained.
CIRCULATING AIR AND FILTERS
Ductwork
The supply duct should be provided with an access panel large
enough to inspect the air chamber downstream of the heat ex-
changer. A cover should be tightly attached to prevent air leaks.
Ductwork dimensions are shown in the roof curb installation
manual.
If desired, supply and return duct connections to the unit may be
made with flexible connections to reduce possible unit operating
sound transmission.
VENTING
NOTE: Venting is self-contained.
CONDENSATE DRAIN CONNECTION
Condensate Drain Connection
A 1” female NPT drain connection is supplied on the end of the
condensate pan, with an alternative connection on the bottom of
the pan. An extrnal trap must be installed for proper condensate
drainage.
Drain Pan (Side View)
NOTE:
Trap should be deep enough to offset maximum
unit static difference. A minimum 4” trap is recommended.
Drain Plug
Roof Curb
See NOTE
Base Rail
Open Vent
2” Min
DRAIN CONNECTION
Install condensate drain trap as shown. Use 1” drain line and fittings
or larger. Do not operate without trap.
Horizontal Drain
Drainage of condensate directly onto the roof may be acceptable;
(refer to local code). It is recommended that a small drip pad of
either stone, mortar, wood or metal be provided to prevent any
possible damage to the roof. When using the horizontal drain
connection, check the drain plug in bottom connection to ensure
it is tight.
Cleaning
Due to the fact that drain pans in any air conditioning unit will
have some moisture in them, algae and fungus will grow due to
airborne bacteria and spores. Periodic cleaning is necessary to
prevent this build-up from plugging the drain.
