Table 4
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.)
F
igure 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.
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.
VENTING
LABEL
POWER EXHAUSTER
PRESSURE
SWITCH
JUNCTION
BOX
FAN GUARD
FAN MOTOR
SIGHT GLASS
GAS SUPPLY
CONNECTION
(Not Shown)
ACCESS PANEL
COMBUSTION AIR
INLET COLLAR
LIGHTING
INSTRUCTION &
RATING PLATE
12
CHECKING INPUT RATE
Figure 11b
COMBINATION
GAS CONTROL
PRESSURE REGULATOR
ADJUSTMENT SCREW
(UNDER CAP SCREW)
MANIFOLD
PRESSURE TAP
PILOT
TUBING
IGNITION
CONTROL
IGNITION
CABLE
MAIN BURNER
MANIFOLD
Time for 1 Input, Cu. Ft. per Hour, When Meter Dial Size is:
Revolution,
Sec. 1/2 cu. ft. 1 cu. ft. 2 cu. ft. 5 cu. ft.
10
180 360 720 1800
12
150 300 600 1500
14
129 257 514 1286
16
112 225 450 1125
18
100 200 400 1000
20
90 180 360 900
22
82 164 327 818
24
75 150 300 750
26
69 138 277 692
28
64 129 257 643
30
60 120 240 600
35
51 103 206 514
40
45 90 180 450
45
40 80 160 400
50
36 72 144 360
55
33 65 131 327
60
30 60 120 300
70
26 51 103 257
80
22 45 90 225
90
20 40 80 200
100
18 36 72 180
1
20
15 30 60 150
Figure 11a
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.
Heater Parts from ACF Greenhouses
