Meter-Timing Gas; Dials Of Typical Gas Meter - Modine Manufacturing PSH Installation And Service Manual

CHECKING INPUT RATE
Table 4
Time for 1 Input, Cu. Ft. per Hour, When Meter Dial Size is:
Revolution,
Sec. 1/2 cu. ft.
10 180
12 150
14 129
16 112
18 100
20 90
22 82
24 75
26 69
28
64
30 60
35
51
40 45
45
40
50 36
55
33
60 30
70 26
80 22
90 20
100 18
120 15

Meter-Timing Gas

(Time required for one revolution is charted for various size
meter dials and various rates of gas input in cu. ft. per hour. To
convert to Btuh, multiply by the heating value of the gas used.)
Figure 10

Dials of Typical Gas Meter

(B) Pressure Method
The pressure method determines input by measuring the
pressure of the gas in the manifold in inches of water.
1. Determine correct manifold pressure from Table 5.
2. Remove access panel (see Figure 11a) and locate
combination gas control.
3. Move gas control knob (or lever) to off.
4. Remove the 1/8" pipe plug in outlet pressure tap in
combination gas control (see Figure 11b) and attach water
manometer or "U" tube which is at least 12" high.
5. Follow lighting instructions and turn thermostat up to get
unit to fire.
CAUTION
Check the gas inlet pressure at the unit upstream of the
combination gas control. The inlet pressure should be 6"-7"
W.C. on natural gas or 11"-14" W.C. on propane. If inlet pressure
is too high, install and additional pressure regulator upstream of
the combination gas control.
Important —Inlet pressure and manifold pressure must be
checked with unit in operation when making final adjustments.
12
1 cu. ft. 2 cu. ft. 5 cu. ft.
360 720 1800
300 600 1500
257 514 1286
225 450 1125
200 400 1000
180 360 900
164 327 818
150 300 750
138 277 692
129 257 643
120 240 600
103 206 514
90 180 450
80 160 400
72 144 360
65 131 327
60 120 300
51 103 257
45 90 225
40 80 200
36 72 180
30 60 150
6. If pressure as indicated by "U" tube is less than 1/2" higher
or lower than indicated in TAble 5, adjust regulator as
described under "meter-Timing method," Step 3.
If pressure as indicated by "U" tube is more than 1/2"
higher or lower than indicated in Table 5, check inlet
pressure at unit. The inlet pressure should be 6"-7" W.C.
pressure on natural gas and 11"-14" W.C. on propane gas.
After adjustment move gas control knob (or level) to off and
replace 1/8" pipe plug. With plug in place move knob (or leave)
to on.) Replace the access panel, making use a good tight seal
is achieved around the entire perimeter of the access panel.
Figure 11a
VENTING
LABEL
LIGHTING
INSTRUCTION &
RATING PLATE
COMBUSTION AIR
INLET COLLAR
Figure 11b
IGNITION
MANIFOLD
CONTROL
PILOT
TUBING
IGNITION
MAIN BURNER
CABLE
Heater Parts from ACF Greenhouses
POWER EXHAUSTER
PRESSURE
SWITCH
JUNCTION
BOX
FAN GUARD
FAN MOTOR
SIGHT GLASS
GAS SUPPLY
CONNECTION
(Not Shown)
ACCESS PANEL
COMBINATION
GAS CONTROL
MANIFOLD
PRESSURE REGULATOR
PRESSURE TAP
ADJUSTMENT SCREW
(UNDER CAP SCREW)