JOHNSON CONTROLS
49
SECTION 3 – START-UP
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
3
MANIFOLD PRESSURE – MODULATING GAS
TABLE 14 -
LOW FIRE (INDUCER FAN ON LOW, 1.4"
W.C. INPUT TO MAXITROL VALVE)
INPUT VOLTAGE TO SIGNAL
CONDITIONER (VDC)
MANIFOLD
PRESSURE (“W.C.)
0.0
0.22
0.5
0.22
1.0
0.22
1.5
0.22
2.0
0.22
2.5
0.32
3.0
0.45
3.5
0.66
4.0
0.84
4.5
1.05
5.0
1.25
5.5
1.30
6.0
1.30
6.5
1.30
TABLE 15 -
HIGH FIRE (INDUCER FAN ON HIGH,
3.5" W.C. INPUT TO MAXITROL VALVE)
INPUT VOLTAGE TO SIGNAL
CONDITIONER (VDC)
MANIFOLD PRESSURE
(“W.C.)
4.0
1.10
4.5
1.40
5.0
1.70
5.5
2.10
6.0
2.50
6.5
2.90
7.0
3.15
7.5
3.25
8.0
3.30
8.5
3.30
9.0
3.30
HIGH FIRE PRESSURE
REGULATOR
LOW FIRE
PRESSURE
REGULATOR
TWO STAGE
PRESSURE
REGULATOR
REGULATOR VENT COVER
INLET
LD11760A
FIGURE 16 -
MANIFOLD GAS PRESSURE
ADJUSTMENT
Manifold Gas Pressure Adjustment
Small adjustments to the manifold gas pressure can be
made by following the procedure outlined below. Refer
to
for the high and low fire
pressure regulator adjustment locations.
1. Turn the gas OFF to the unit.
2. Use a 3/16 inch Allen wrench to remove the 1/8
inch NPT plug from the outlet pressure tap of the
valve.
3. Install a brass adapter to allow the connection of a
hose to the outlet pressure tap of the valve.
4. Connect the hose to a manometer capable of read-
ing the required manifold pressure value.
5. Turn the gas back ON.
6.
Place the heat section into high fire operation.
7.
Compare the high fire manifold pressure to
8.
To adjust the high fire manifold pressure remove
the cap from the high fire pressure regulator. Use a
3/32 Allen wrench to make the manifold pressure
adjustment. To increase the manifold pressure,
turn the screw clockwise; to decrease the mani-
fold pressure, turn the screw counterclockwise.
Place your finger over the adjustment opening
while verifying the manifold pressure.
9.
Place the heat section into low fire operation.
10.
Compare the low fire manifold pressure to
11.
To adjust the low fire manifold pressure remove
the cap from the low fire pressure regulator. Use
a 3/32 inch Allen wrench to make the manifold
pressure adjustment. To increase the manifold
pressure, turn the screw clockwise; to decrease
the manifold pressure, turn the screw counter-
clockwise. Place your finger over the adjustment
opening while verifying the manifold pressure.
12. Turn the heat OFF.
13. Turn the gas OFF.
14. Remove the brass tubing adapter and replace the
plug in the outlet pressure tap.