29
GAS PIPING CONNECTIONS
Gas Piping Checks
Before placing unit in operation, leak test the unit and gas
connections.
Check for leaks using an approved chloride-free soap and
water solution, an electronic combustible gas detector, or
other approved testing methods.
NOTE:
Never exceed specified pressures for testing. Higher
pressure may damage the gas valve and cause subsequent
overfiring, resulting in heat exchanger failure.
Disconnect this unit and shutoff valve from the gas supply
piping system before pressure testing the supply piping
system with pressures in excess of ½ psig (3.48 kPa).
Isolate this unit from the gas supply piping system by closing
its external manual gas shutoff valve before pressure testing
supply piping system with test pressures equal to or less
than ½ psig (3.48 kPA).
Propane Gas Tanks and Piping
CAUTION
Never allow the products of combustion, including carbon
monoxide, to enter the return duct work or circulation air
supply.
A gas detecting warning system is the only reliable way
to detect a propane gas leak. Rust can reduce the level
of odorant in propane gas. Do not rely on your sense of
smell. Contact a local propane gas supplier about installing
a gas detecting warning system. If the presence of gas
is suspected, follow the instructions listed in the Safety
Considerations section of this manual.
All propane gas equipment must conform to the safety
standards of the National Board of Fire Underwriters, NBFU
Manual 58. CANADA: National Standard of Canada, Natural
Gas and Propane Installation Code (NSCNGPIC) CAN/CSA
B149.1-15.
For satisfactory operation, propane gas pressure must be
10” WC at the furnace manifold with all gas appliances in
operation. Maintaining proper gas pressure depends on
three main factors:
1.
Vaporization rate, depending on temperature of the
liquid, and “wetted surface” area of the container or
containers.
2. Proper pressure regulation. (Two-stage regulation is
recommended for both cost and efficiency).
3. Pressure drop in lines between regulators, and
between second stage regulator and the appliance.
Pipe size will depend on length of pipe run and total
load of all appliances.
Complete information regarding tank sizing for vaporization,
recommended regulator settings, and pipe sizing is
available from most regulator manufacturers and propane
gas suppliers.
Since propane gas will quickly dissolve white lead and most
standard commercial compounds, special pipe dope must
be used. Always use a pipe thread sealant approved for all
gases.
Refer to the Figure 35 for typical propane gas installations
and piping.
200 PSIG
Maximum
5 to 15 PSIG
(20 PSIG Max.)
Continuous
11" W.C.
Second Stage
Regulator
First Stage
Regulator
Propane Gas Installation (Typ.)
Figure 35
CIRCULATING AIR & FILTERS
Duct work - Air Flow
Duct systems and register sizes must be properly
designed for the CFM and external static pressure rating
of the furnace. Design the ductwork in accordance with the
recommended methods of “Air Conditioning Contractors of
America” Manual D.
Install the duct system in accordance with Standards of the
National Board of Fire Underwriters for the Installation of
Air Conditioning, Warm Air Heating and Ventilating Systems.
Pamphlets No. 90A and 90B.
Checking Static Pressure
(80% Furnace Shown, 90% Similar
Figure 36