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NOTE: If measuring gas pressure at the drip leg or Honeywell
VR9205R gas valve, a field-supplied hose barb fitting must be
installed prior to making the hose connection.
3. Turn ON the gas supply, check for leaks and operate
the furnace and all other gas consuming appliances
on the same gas supply line.
NOTE: To bring furnace up to High Fire, see
instructions for field test mode in GAS MANIFOLD
PRESSURE MEASUREMENT section.
4. Measure furnace gas supply pressure with burners firing.
Supply pressure must be within the range specified in
the Inlet Gas Supply Pressure table.
Inlet Gas Supply Pressure
Natural Gas
Minimum:
Propane Gas
Minimum: 11.0" w.c.
If supply pressure differs from table, make the necessary ad-
justments 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 threaded 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
M
AS
ANIFOLD
RESSURE
T
O PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE
INLET GAS SUPPLY PRESSURE MUST BE AS SPECIFIED ON THE UNIT
RATING PLATE WITH ALL OTHER HOUSEHOLD GAS FIRED APPLIANCES
.
OPERATING
The manifold pressure must be measured with the burners
operating. To measure the manifold pressure, use the fol-
lowing procedure:
1. Turn OFF gas to furnace at the manual gas shutoff valve
external to the furnace.
42
4.5" w.c.
Maximum: 10.0" w.c.
Maximum: 13.0" w.c.
Gas Line
To Furnace
Open To
Atmosphere
Manometer Hose
Manometer
Figure 51
EASUREMENT
CAUTION
2. Turn off all electrical power to the system.
3. Outlet pressure tap connections: Remove the outlet
pressure tap plug. Install an 1/8" NPT hose barb fitting
into the outlet pressure tap. Refer to gas valve diagram
on preceding page.
4. Attach a hose and manometer to the outlet pressure
barb fitting.
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. Modulating furnaces light at 80% of max input. For
natural gas, the expected manifold pressure at
ignition will be in a range of 1.8" - 2.5" W.C. For LP
gas, the range will be 5.8" - 6.8" W.C.
NOTE: Measure the gas manifold pressure with the
burners firing. After every time the main power is
turned off and back on, the furnace will enter a
calibration routine on the next call for heat The
inducer will ramp up and down during the
calibration routine. After calibration, the furnace
will proceed to ignition cycle.
8. Field Test Mode is intended to help a service person
troubleshoot and check out an installed appliance
by bringing the furnace up to High fire (100% input),
by-passing the normal modulating routing.
To enter Field Test Mode the Fault Recall Push-
Button must be pressed twice within a 5 second
period at any time during a heating cycle, at which
time the display will show "Ft". While the display
is showing "Ft", pressing and holding the Fault
Recall Push-Button for 3 seconds will enable the field
test mode and override the normal firing rate
sequence at a rate of 100% for 5 minutes or until
the end of the call for heat. The display will show
the normal "Hi" while the control is firing at 100%.
If the Fault Recall Push-Button has not been pressed
within 5 seconds of displaying "Ft" the display will
revert back to normal.
NOTE: Gas valve is factory set and does NOT require
any field adjustment. Do NOT attempt to adjust
valve.
9. Turn off all electrical power and gas supply to the
system.
10. Remove the manometer hose from the hose barb fitting.
11. Remove the 1/8" NPT hose barb fitting from the outlet
pressure tap. Replace the outlet pressure tap plug and
,
THE
seal with a high quality thread sealer.
12. Turn on electrical power and gas supply to the system.
13. Close thermostat contacts "R" and "W1/W2" to
energize the valve.
Using an approved liquid gas leak detector solution, check for
leaks at outlet pressure tap plug. Bubbles forming indicate a
leak. SHUT OFF GAS AND REPAIR ALL LEAKS IMMEDIATELY!
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