Gas Valve; Inlet Gas Pressure Range; Nominal Manifold Pressure - Johnson Controls TM9T Series Installation Manual

1083286-UIM-L-1219
ADJUSTMENT OF MANIFOLD GAS PRESSURE &
INPUT RATE
Inlet and manifold gas pressure may be measured by connecting the
"U" tube manometer to the gas valve with a piece of tubing. Follow the
appropriate section in the instructions below. Refer to Figure 35 for the
locations of the pressure ports on the gas valve.
Turn gas off at the ball valve or gas cock on gas supply line
before the gas valve. Find the pressure ports on the gas
valve marked Out P and In P.
1. The manifold pressure must be taken at the port marked OUT P.
2. The gas line pressure must be taken at the port marked IN P.
3. Using a 3/32" (2.4 mm) Allen wrench, loosen the set screw by turn-
ing it 1 turn counter clockwise. DO NOT REMOVE THE SET
SCREW FROM THE PRESSURE PORT.
Read the inlet gas pressure
Connect the positive side of the manometer to the IN P Tap on the gas
valve. Do not connect any tubing to the negative side of the manometer,
as it will reference atmospheric pressure. Refer to Figures 35 and 36 for
connection details.
1. Turn gas and electrical supplies on and follow the operating instruc-
tions to place the unit back in operation.
Table 16: Inlet Gas Pressure Range

INLET GAS PRESSURE RANGE

Natural Gas
Minimum 4.5" w.c. (1.12 kPa)
Maximum 10.5" w.c. (2.61 kPa)
IMPORTANT: The inlet gas pressure operating range table specifies
what the minimum and maximum gas line pressures must be for the
furnace to operate safely. The gas line pressure MUST BE a mini-
mum of:
• 7" w.c. (1.74 kPA) for Natural Gas
• 11" w.c. (2.74 kPA) for Propane (LP) Gas
in order to obtain the BTU input specified on the rating plate and/or
the nominal manifold pressure specified in these instructions and on
the rating plate.
2. Once the correct gas inlet pressure has been established, see
Table 16, turn the gas valve to OFF and turn the electrical supply
switch to OFF; then remove the flexible tubing from the gas valve
pressure tap and tighten the pressure tap plug using the 3/32" (2.4
mm) Allen wrench.
3. Turn the electrical and gas supplies back on, and with the burners
in operation, check for gas leakage around the gas valve pressure
port for leakage using an approved non-corrosive gas leak detec-
tion fluid, or other non-flammable leak detection methods.
Read the manifold gas pressure
Connect the positive side of the manometer to the OUT P Tap on the
gas valve. Do not connect any tubing to the negative side of the
manometer, as it will reference atmospheric pressure. Refer to Figures
35 and 36 for connection details.
IMPORTANT: The cap for the pressure regulator must be removed
entirely to gain access to the adjustment screw. Loosening or tighten-
ing the cap does not adjust the flow of gas.
32
This gas valve has separate regulator adjustment screws for high fire
and low fire, as shown in Figure 35. The procedure below is used to
adjust either the high fire manifold pressure or the low fire manifold
pressure.
1. Refer to Figure 35 for location of pressure regulator adjustment cap
2. Turn gas and electrical supplies on and follow the operating instruc-
3. Place jumper wire from W1 to W2 to R on the furnace control board
Table 17: Nominal Manifold Pressure
Propane (LP)
8.0" w.c. (1.99 kPa)
13.0" w.c. (3.24 kPa).
FIGURE 35: Gas Valve
4. After the manifold pressure has been adjusted, re-calculate the fur-
5. Once the correct BTU (kW) input has been established, turn the
6. Turn the electrical and gas supplies back on, and with the burners
NOTICE
Gas manifold pressure must be set on high fire before adjusting low
fire pressure.
and adjustment screws on main gas valve.
tions to place the unit back in operation.
for the furnace to operate HIGH fire. Once correct manifold pres-
sure is set (HI), remove jumper from W2 for the furnace to operate
on low fire. Set the manifold pressure (LO) to correct manifold pres-
sure.

NOMINAL MANIFOLD PRESSURE

Natural Gas (High Fire)
Natural Gas (Low Fire)
Propane (LP) Gas (High Fire)
Propane (LP) Gas (Low Fire)
HIGH STAGE REGULATOR
ADJUSTMENT
OUTLET
PRESSURE
PORT
INLET
WRENCH
BOSS
INLET
PRESSURE
PORT
ON OFF
SWITCH
IMPORTANT: If gas valve regulator is turned in (clockwise), manifold
pressure is increased. If screw is turned out (counterclockwise), man-
ifold pressure will decrease.
nace input to make sure you have not exceeded the specified input
on the rating plate. Refer to "CALCULATING THE FURNACE
INPUT (NATURAL GAS)".
gas valve to OFF and turn the electrical supply switch to OFF; then
remove the flexible tubing from the gas valve pressure tap and
tighten the pressure tap plug using the 3/32" (2.4 mm) Allen
wrench.
in operation, check for gas leakage around the gas valve pressure
port for leakage using an approved non-corrosive gas leak detec-
tion fluid, or other non-flammable leak detection methods.
3.5" w.c. (0.87 kPa)
1.6" w.c. (0.40 kPa)
9.8" w.c. (2.488 kPa)
4.0" w.c. (0.99 kPa)
VENT
PORT
OUTLET
LOW STAGE REGULATOR
ADJUSTMENT
Johnson Controls Ducted Systems