CAUTION
The gas valve body is a very thin casting that cannot
take any external pressure. Never apply a pipe
wrench to the body of the gas valve when installing
piping. A wrench must be placed on the octagon hub
located on the gas inlet side of the valve. Placing a
wrench to the body of the gas valve will damage the
valve causing improper operation and/or the valve to
leak.
CAUTION
Burner ignition may not be satisfactory on first startup
due to residual air in the gas line or until gas manifold
pressure is adjusted. The ignition control makes
three attempts to light before locking out. After three
trials for ignition, if the appliance does not operate,
follow the instructions Turning off the appliance in the
User's Information Manual and call your gas supplier
to verify the quality and/or consistency of the gas
supply. If the gas supply has been verified and/or
other gas appliances are operating properly, and the
appliance still does not ignite, call service to properly
troubleshoot the unit.
It is possible to connect gas piping from either side of the
furnace using any of the gas pipe entry knockouts on both
sides of the furnace. See Figure 15.
Gas orifice conversion for propane (LP)
This furnace is factory-made for natural gas-fired
operation, but it is possible to convert it to operate
on propane (LP) gas by using a factory-supplied LP
conversion kit. Follow the instructions supplied with the
LP kit.
WARNING
LoNOx furnaces requiring propane (LP) gas must
have the LoNOx screens removed prior to installation
and operation. Refer to the propane kit conversion
instructions.
WARNING
Examine the burner flames to make sure they are in
good adjustment. Look to a pure blue flame with a
light blue cone at its center that burns full, steady and
straight. If yellow or orange, or a partial, diverted, or
unsteady flame is detected, then turn off gas valves
and clean any debris from nozzles and pilot light. If
condition still exists, then check airflow, venting, gas
pressure, etc. If condition still exists, contact technical
service for further instructions.
High altitude gas orifice conversion
This furnace is factory-made for natural gas-fired
operation at 0 ft to 5,000 ft (0 m to 1,524 m) above sea
level.
To maintain correct and safe operation, it is essential to
change the manifold pressure when installing the furnace
in a location where the altitude is greater than 5,000 ft
(1,524 m) above sea level. See Table 4 for the correct
manifold pressure settings.
Table 4: Nominal Manifold Pressure
Manifold pressures (in. W.C.)
at different altitude ranges (ft)
Manifold pressures (kPa) at
different altitude ranges (m)
Gas heating
halue
(Btu/ft
3
)
0–7999 8000–8999 9000–9999
Gas heating
value
(MJ/m
3
)
0–2437 2438–2742 2743–3048
800 3.5 3.5 3.5 29.8 0.87 0.87 0.87
850 3.5 3.5 3.5 31.7 0.87 0.87 0.87
900 3.5 3.5 3.5 33.5 0.87 0.87 0.87
950 3.5 3.5 3.3 35.4 0.87 0.87 0.81
1000 3.5 3.2 2.9 37.3 0.87 0.80 0.73
1050 3.5 2.9 2.7 39.1 0.87 0.73 0.67
1100 3.2 2.7 2.4 41.0 0.80 0.66 0.61
2500 (LP) 9.8 8.2 7.5 93.2 (LP) 2.44 2.03 1.86
Installation Manual: RL18 Single-Stage Standard ECM Residential Gas Furnaces (Non-condensing Multi-position Standard
Low NOx)
18
Johnson Controls Ducted Systems
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