Carrier 59MN7B Installation, Start-Up, Operating And Service And Maintenance Instructions page 68

ON/OFF Switch
Turn screw 1 click per
second to adjust rate.
Clockwise to increase
rate, counter clockwise
to decrease rate.
Inlet
Pressure Tap
Representative drawing only, some models may vary in appearance.
Fig. 60 - - Gas Valve without Tower Pressure Ports
MANIFOLD PRESSURE TAP
SET SCREW: 3/32" HEX HEAD
ACCEPTS 5/16" HOSE
CONNECTION
1/2" NPT
INLET
INLET PRESSURE TAP
SET SCREW:
3/32" HEX HEAD
ACCEPTS 5/16" HOSE
ON/OFF SWITCH
CONNECTION
Representative drawing only, some models may vary in appearance.
Fig. 61 - - Gas Valve with Tower Pressure Ports
Adjust Manifold Pressure - - Minimum Heat
To adjust manifold pressure to obtain input rate for Minimum
Heat:
1. Turn SW1- -2 ON and SW4- -2 must be OFF.
2. Jumper R and W/W1 thermostat connections on control to
start furnace.
3. After the main burners ignite and the blower starts, confirm
Minimum Heat manifold pressure is correct, based on the
manifold pressure tables in the installation instructions.
4. To adjust the Minimum Heat manifold pressure, slowly
turn adjusting screw counterclockwise to decrease manifold
pressure or clockwise to increase manifold pressure. Turn
adjustment no more than one click per second until you ob-
tain the required manifold pressure. See Fig. 60.
5. After adjusting the manifold pressure, remove jumpers
across thermostat connections to terminate the call for heat.
Wait until the blower off delay is completed.
6. Move setup switch SW1- -2 to the OFF position.
MODULATING
Min/Max Heat Adust
(Under Cap)
1/2" NPT Outlet
Manifold
Pressure Tap
1/2" NPT
OUTLET
OUTP
MIN/MAX HEAT
ADJUST (UNDER CAP)
A170116
!
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Manifold pressure tap set screw must be tightened and
⅛
- -in. NPT pipe plug must be installed to prevent gas leaks.
Clocking The Meter
Verify natural gas input rate by clocking meter.
NOTE: Contact your HVAC distributor or gas supplier for metric
gas meter Tables, if required.
1. Turn off all other gas appliances and pilots served by the
meter.
2. Move setup switches SW1- -2 to ON position and SW4-2 to
OFF. This keeps furnace locked in low--heat operation
when only W/W1 is energized or high heat operation when
R to W/W1 and W2 are jumpered.
3. Jumper R to W/W1 and W2. Run furnace for 3 minutes in
maximum heat operation.
4. Measure time (in sec) for gas meter to complete one
A10496
revolution and note reading. The 2 or 5 cubic feet dial
provides a more accurate measurement of gas flow.
5. Refer to Table 18 for cubic ft. of gas per hr. Multiply gas
rate cu ft./hr by heating value (Btuh/cu ft.) to obtain input
rate.
6. If clocked rate does not match required input from Step 5,
increase manifold pressure to increase input or decrease
manifold pressure to decrease input. Repeat steps 3 through
5 until correct maximum heat input is achieved. See Fig.
62.
Manifold
NOTE: Setup switches SW1- -2 must be ON and SW4- -2 must be
OFF. This keeps furnace locked in minimum heat operation when
R to W/W1 is energized. Repeat items 3 through 6 for minimum
heat operation until minimum heat input is achieved.
7. Remove jumpers across thermostat connections to
terminate the call for heat. Wait until the blower off delay is
completed then reset 115- -v power to furnace.
8. Restore furnace to normal operating condition.
9. Remove jumpers across thermostat connections to termi- -
nate the call for heat. Wait until the blower off delay is
completed.
10. Disconnect 115 VAC power to furnace.
11. Turn gas valve ON/OFF switch to OFF.
68
WARNING
Burner Flame
Fig. 62 - - Burner Flame
Burner
A11461