Gas Manifold Pressure Measurement And Adjustment; Gas Input Rate Measurement (Natural Gas Only ) - Goodman GCH95 Installation Instructions Manual

If supply pressure differs from table, make the necessary adjust-
ments to pressure regulator, gas piping size, etc., and/or consult
with local gas utility.
5. Turn OFF gas to furnace at the manual shutoff valve and
disconnect manometer. Reinstall plug before turning on
gas to furnace.
6. Turn OFF any unnecessary gas appliances stated in step
3.
Gas Line
Gas
Shutoff
Valve
Drip Leg Cap
With Fitting
Measuring Inlet Gas Pressure (Alt. Method)
G M P
AS ANIFOLD RESSURE
T
O PREVENT UNRELIABLE OPERATION
GAS MANIFOLD PRESSURE MUST
. O
PLATE NLY MINOR ADJUSTMENTS
THE GAS VALVE PRESSURE REGULATOR
Only small variations in gas pressure should be made by adjust-
ing the gas valve pressure regulator. The manifold pressure must
be measured with the burners operating. To measure and adjust
the manifold pressure, use the following procedure.
1. Turn OFF gas to furnace at the manual gas shutoff valve
external to the furnace.
2. Turn off all electrical power to the system.
3. Outlet pressure tap connections:
a. Honeywell VR9205 valve: Remove the outlet pressure
boss plug. Install an 1/8" NPT hose barb fitting into the
outlet pressure tap.
b. White-Rodgers 36G54 valve: Back outlet pressure test
screw (inlet/outlet pressure boss) out one turn
(counterclockwise, not more than one turn).
4. Attach a hose and manometer to the outlet pressure barb
fitting (Honeywell valve) or outlet pressure boss (White-
Rodgers valve).
5. Turn ON the gas supply.
6. Turn on power and close thermostat "R" and "W1" contacts
to provide a call for low stage heat.
7. Measure the gas manifold pressure with burners firing.
Adjust manifold pressure using the Manifold Gas Pressure
table shown below.
Gas Line
To Furnace
Open To
Atmosphere
Manometer Hose
Manometer
M A
EASUREMENT AND DJUSTMENT
CAUTION
OR EQUIPMENT DAMAGE
BE AS SPECIFIED ON THE UNIT
SHOULD BE MADE BY ADJUSTING
.
8. Remove regulator cover screw from the low (LO) outlet
pressure regulator adjust tower and turn screw clockwise
to increase pressure or counterclockwise to decrease
pressure. Replace regulator cover screw.
9. Close thermostat "R" and "W2" contacts to provide a call for
high stage heat.
10. Remove regulator cover screw from the high (HI) outlet
pressure regulator adjust tower and turn screw clockwise
to increase pressure or counterclockwise to decrease
pressure. Replace regulator cover screw.
11. Turn off all electrical power and gas supply to the system.
12. Remove the manometer hose from the hose barb fitting or
outlet pressure boss.
13. Replace outlet pressure tap:
a. Honeywell VR9205 valve: Remove the 1/8" NPT hose barb
fitting from the outlet pressure tap. Replace the outlet
pressure boss plug and seal with a high quality thread
sealer.
b. White-Rodgers 36G54 valve: Turn outlet pressure test
screw in to seal pressure port (clockwise, 7 in-lb
minimum).
14. Turn on electrical power and gas supply to the system.
15. Close thermostat contacts "R" and "W1/W2" to energize the
valve.
Using a leak detection solution or soap suds, check for leaks at
outlet pressure boss plug (Honeywell valve) or screw (White-Rodg-
ers valve). Bubbles forming indicate a leak. SHUT OFF GAS AND
REPAIR ALL LEAKS IMMEDIATELY!
NOTE: For gas to gas conversion, consult your dealer for
appropriate conversion.
Gas
,
THE
RATING
Natural
Propane
G I R
AS NPUT ATE
The gas input rate to the furnace must never be greater than that
specified on the unit rating plate. To measure natural gas input
using the gas meter, use the following procedure.
1. Turn OFF the gas supply to all other gas-burning appliances
except the furnace.
2. While the furnace is operating, time and record one
complete revolution of the smallest gas meter dial.
3. Calculate the number of seconds per cubic foot (sec/ ft
gas being delivered to the furnace. If the dial is a one cubic
foot dial, divide the number of seconds recorded in step 2
by one. If the dial is a two cubic foot dial, divide the number
of seconds recorded in step 2 by two.
4. Calculate the furnace input in BTUs per hour (BTU/ hr). Input
equals the installation's gas heating value multiplied by a
conversion factor (hours to seconds), divided by the number
of seconds per cubic foot. The measured input must not be
greater than the input indicated on the unit rating plate.
EXAMPLE:
Installation's gas heating (HTG) value: 1,000 BTU/ft
(Obtained from gas supplier)
32
Manifold Gas Pressure
Rate Range
Low Stage 1.7 to 2.3" w.c.
High Stage 3.2 to 3.8" w.c.
Low Stage 5.7 to 6.3" w.c.
High Stage 9.7 to 10.3" w.c. 10.0" w.c.
M (N
EASUREMENT ATURAL
Nominal
2.0" w.c.
3.5" w.c.
6.0" w.c.
G O )
AS NLY
3
) of
3