Reznor RPB Manual

I-RPB (04-21) 131782-A, Page 10
6.0 Mechanical
(cont'd)
6.1 Gas Piping
and Pressures
(cont'd)
Measuring manifold gas pressure cannot be done until the heater is in operation. It is
included in the steps of the Check-Test-Start procedure in Paragraph 9.0. The following
warnings and instructions apply.
WARNING
Manifold gas pressure must never exceed 3.5 IN WC for natural
gas and 10 IN WC for propane gas.
For Natural Gas: When the heater leaves the factory, the combination valve is set so
that the outlet gas pressure of a single-stage valve or high re of a two-stage valve is
regulated to 3.5 IN WC. Low re on a two-stage valve is set to 1.8 IN WC. Inlet supply
pressure to the valve must be a minimum of 5 IN WC or as noted on the rating plate
and a maximum of 14 IN WC. NOTE: Always check the rating plate for minimum
gas supply pressure. Minimum supply pressure requirements vary based on size of
burner and the gas control option. Most units require a minimum of 5 IN WC of natu-
ral gas as stated above, but Sizes 350 and 400 with electronic modulation require a
minimum of 6 IN WC natural gas supply pressure. Sizes 300 and 350 with mechanical
modulation require 7 IN WC.
For Propane: When the heater leaves the factory, the combination valve is set so that
the outlet gas pressure of a single-stage valve or high re of a two-stage valve is 10 IN
WC. Low re on a two-stage valve is set to 5 IN WC. Inlet pressure to the valve must
be a minimum of 11 IN WC and a maximum of 14 IN WC.
Before attempting to measure or adjust manifold gas pressure, the inlet (supply) pres-
sure must be within the specied range for the gas being used both when the heater is
in operation and on standby. Incorrect inlet pressure could cause excessive manifold
gas pressure immediately or at some future time.
Manifold or Orice (Valve Outlet) Pressure Settings
Instructions to Check Valve Outlet (Manifold) Pressure:
1) With the manual valve (on the combination valve) positioned to prevent ow to the
main burners, connect a manometer to the 1/8" pipe outlet pressure tap in the valve.
NOTE: A manometer (uid-lled gauge) is recommended rather than a spring type
gauge due to the di󰀩culty of maintaining calibration of a spring type gauge.
2) Open the valve and operate the heater. Measure the gas pressure to the manifold.
To measure the low stage pressure on units equipped with a two-stage valve, discon-
nect the wire from the "HI" terminal on the valve. Be sure to reconnect the wire.
Normally adjustments should not be necessary to the factory preset regulator. If adjust-
ment is necessary, set pressure to correct settings by turning the regulator screw IN
(clockwise) to increase pressure. Turn regulator screw OUT (counterclockwise) to
decrease pressure. Consult the valve manufacturer's literature provided with the fur-
nace for more detailed information.
CAUTION: DO NOT bottom out the gas valve regulator adjusting screw.
This can result in unregulated manifold pressure causing overre and
heat exchanger failure.

Reznor RPB Specifications

General

Brand	Reznor
Model	RPB
Category	Furnace
Language	English