Reznor RXH (Outdoor PreevA) Unit Installation Manual - Manual (Page 17)

Form I-RDH/REH/RHH/RXH (12-14), P/N 215210 R14, Page 17
1) Gas Valve Pressure Tap Locations
Locate the 1/8” outlet pressure tap on the single or two-stage valve (See
FIGURE
11A). With the manual valve turned off to prevent flow to the gas valve, connect a
manometer to the 1/8” outlet pressure tap in the valve. Both high-fire and low-fire outlet
pressure can be checked at this pressure tap.
2) Measure Outlet Pressure and Adjust (if needed)
Open the manual valve and operate the heater.
Using the manometer connected to the valve, measure the outlet pressure of the sin-
gle-stage gas valve or high fire on a two-stage valve. To measure low-stage pressure
on units with a two-stage valve (Options AG2, AG3, AG15, AG16, AG60, AG61, AG62,
DG1, DG5, and D12C), disconnect the wire from the “HI” terminal on the valve. Mea-
sure gas pressure with the manometer attached to the valve. Re-connect the wire.
Normally, when operating at the altitude indicated on the rating plate, adjust-
ments to the factory settings should not be necessary. If adjustment is required,
remove the cap from the adjustment screw on the single or two-stage valve. Adjust
pressure setting by turning the regulator screw IN (clockwise) to increase pressure.
Turn regulator screw OUT (counterclockwise) to decrease pressure. If an adjustment
is made, turn up the thermostat. Cycle the burner once or twice to properly seat the
adjustment spring in the valve. Re-check the pressure. When the outlet pressure is
right for the installation, remove the manometer and replace the cap. Check for a leak
at the pressure tap fitting.
WARNING
Valve outlet gas pressure must never exceed the value listed in
TABLE 11 (or as shown on the rating plate).
1) Gas Valve Pressure Tap Locations
The manifold includes a single-stage valve and a modulating valve (
FIGURE 11B).
Locate the outlet pressure tap just behind the orific adapter (See FIGURE 11A above).
To check high fire outlet pressure, connect a manometer to the outlet pressure tap just
behind the orific adapter.
To check low-fire (bypass pressure), locate the 1/4” NPT pressure tap just behind the
orifice adapter as shown in FIGURE 11C. Connect a manometer to the 1/4” pressure tap.
Low Fire
Outlet
Adjustment
Screw
High Fire Outlet
Adjustment Screw
Inlet
Pressure Tap
Two-Stage
Combination Valve
1/8” Outlet Pressure Tap
FIGURE 11A - Top Views of Valves Showing Outlet
Pressure Tap and Adjustment Locations
Single-Stage Combination Valves
CAUTION: DO NOT
bottom out the gas
valve regulator
adjusting screw.
This can result in
unregulated manifold
pressure causing
excess overfire and
heat exchanger
failure.
INSTRUCTIONS for single-
stage and two-stage gas
control options (Options
AG1, AG2, AG3, AG15,
AG16, AG60, AG61, AG62,
DG1, DG5, D12C)
The outlet pressure is regulated by the combination single or two stage gas valve. The
combination valve outlet pressure should be as shown in TABLE 11, page 20, (for the
model size, gas type, gas control option, and altitude of the installation) or as noted on
the rating plate.
Modulating Valve in
Options AG8, AG9,
AG9H, AG40, DG2,
DG6, and D12B -- DO
NOT adjust.
To ensure an accurate high fire
reading at the single-stage valve, a
minimum signal of 20VDC must be
present at the modulating valve.
FIGURE 11B - Top View
of Modulating Valve in
AG8, AG9, AG9H, AG40,
DG2, DG6, and D12B
1/8” Outlet
Pressure
Tap
Inlet Pressure Tap
Adjust Outlet
Pressure
1/8” Outlet
Pressure Tap
Adjust Outlet
Pressure
Inlet
Pressure
Tap
INSTRUCTIONS
for ELECTRONIC
MODULATION Gas
Control Options AG8,
AG9, AG9H, AG40, DG2,
DG6, and D12B