Setting Gas Pressure - Rheem RGFG Installation Instructions Manual

FIGURE 26
LP JUMPER INSTALLED ON SERVO MODU-
LATING GAS VALVE WITH PINS NOT CON-
NECTED. THIS IS INCORRECT. MAKE
SURE THAT THE JUMPER CONNECTS THE
TWO PINS TOGETHER AND VERIFY MANI-
FOLD GAS PRESSURE AT HIGH FIRE TO
MAKE SURE THE VALVE IS PROPERLY
CONVERTED FOR LP GAS
JUMPER
IMPROPERLY
INSTALLED.
NOTE THAT
PINS ARE
NOT CON-
NECTED.
FIGURE 27
LP JUMPER INSTALLED ON SERVO MODU-
LATING GAS VALVE WITH PINS PROPERLY
CONNECTED. THIS IS CORRECT. MAKE
SURE THAT THE JUMPER CONNECTS THE
TWO PINS TOGETHER AND VERIFY MANI-
FOLD GAS PRESSURE AT HIGH FIRE TO
MAKE SURE THAT THE VALVE IS PROPER-
LY CONVERTED FOR LP GAS
JUMPER
PROPERLY
INSTALLED.
NOTE THAT
PINS ARE
CONNECTED.

SETTING GAS PRESSURE

A properly calibrated pressure gauge
or U-Tube manometer is required for
accurate gas pressure measurements.
CAUTION
ELEVATIONS ABOVE 2000 FT
REQUIRE THAT THE FURNACE
INPUT RATING BE ADJUSTED AND
THAT THE SIZE OF THE BURNER
ORIFICES BE RE-CALCULATED
BASED ON ELEVATION AND GAS
HEATING VALUE. THE BURNER ORI-
FIGURE 28
SERVO-CONTROLLED GAS VALVE MANIFOLD PRESSURE TAP LOCATION
34
FICES MAY (OR MAY NOT) NEED TO
BE CHANGED. SEE THE SECTION
TITLED "HIGH ALTITUDE INSTALLA-
TIONS" OF THIS BOOK FOR
INSTRUCTIONS.
Supply Gas Pressure Measure-ment.
1. With gas shut off to the furnace
at the manual gas valve outside
the unit, remove the line
pressure tap plug on the gas
valve. See Figure 25.
2. Connect a U-Tube manometer to
the pressure tap.
3. Turn on the gas supply and operate
the furnace at 100% and all other
gas-fired units on the same gas line
as the furnace.
4. Note or adjust the supply-line pres-
sure to give:
A. 5" - 10.5" w.c. for natural gas.
B. 11" - 13" w.c. for LP gas.
5. Shut off the gas at the manual gas
valve and remove the
U-Tube manometer.
6. Replace the supply-line pressure
tap plug before turning on the gas.
7. Check unit for leaks.
If the supply-line pressure is above
these ranges, install an in-line gas regu-
lator to the furnace for natural gas units.
With LP gas, have the LP supplier
reduce the supply-line pressure at the
regulator.
If supply-line pressure is below these
ranges, either remove any restrictions in
the gas supply piping or enlarge the gas
pipe. See Tables 9 and 10. With LP gas,
have the LP supplier adjust the supply-
line pressure at the regulator.
MANIFOLD TAP
CAUTION
ELEVATIONS ABOVE 2000 FT
REQUIRE THAT THE FURNACE
INPUT RATING BE ADJUSTED
AND THAT THE SIZE OF THE
BURNER ORIFICES BE RE-CAL-
CULATED BASED ON ELEVATION
AND GAS HEATING VALUE. THE
BURNER ORIFICES MAY (OR MAY
NOT) NEED TO BE CHANGED. SEE
THE SECTION TITLED "HIGH ALTI-
TUDE INSTALLATIONS" OF THIS
BOOK FOR INSTRUCTIONS.
® SERVO GAS VALVE (FUEL
‰ CODE: HA OR HB) MANIFOLD
‰ GAS PRESSURE
‰ MEASUREMENT/ADJUSTMENT.
1. With the gas to the unit shut off
at the manual gas valve, remove
the outlet pressure tap plug in
the gas valve. See Figure 28.
2. Connect the positive pressure
hose from a manometer to the
pressure tap.
3. Note the manifold gas pressure
to be:
A. 3.5" w.c. (±.3) for natural gas .
B. 10.0" w.c. ( ±.5) for LP gas.
NOTE: Make sure the unit is
operating at maximum heating
capacity (100%) before adjusting
the manifold pressure.
4. To adjust the pressure regulator,
insert a small slotted screwdriver
into the opening at the top of the
valve.
NOTE: Only small variations in
gas pressure should be made by
adjusting the pressure regulator.
NOTE: Allow up to 5 seconds for
each change in manifold pres-
sure.
5. Turn the adjustment screw clock-
wise to increase pressure, or
counterclockwise to decrease
pressure.
6. Check manifold gas pressure.
7. Repeat step 5 & 6 if needed.
8. Securely replace the regulator
cap.
NOTE: Shut off gas at the manu-
al gas valve and remove the U-
Tube manometer.
9. Replace the manifold pressure
tap plug before turning on
the gas.
10. Check unit for leaks.
NOTE: Do not use gas valve pres-
sure adjustment as a means to
adjust temperature rise. The blower
motor will change speed to maintain
a reasonably constant temperature
rise.