Verify Manifold Pressure; Input Check And Adjustment - Trane 4DCL4024 Installer's Manual

Installer's Guide
4. Before connecting the piping circuit to the unit, bleed the air
from the supply line and then cap or plug the line and test the
pressure at the tapped shut-off cock. The pressure reading
should not exceed 14 inches water column.
5. Using an appropriate backup wrench on the gas valve inlet boss,
connect the gas piping to the unit. Check the completed piping
for leaks using a soap and water solution or the equivalent.
6. After installation of the gas pipe in the unit, the pipe opening
should be closed with the filler/barrier plug provided.
Manifold Pressure
Check the manifold pressure at the unit gas valve. Do not exceed
the recommended pressure shown on the unit nameplate.

Input Check and Adjustment

1. Make sure all gas appliances are off except the furnace.
2. Clock the gas meter with the furnace operating (determine the dial
rating of the meter) for one revolution.
3. Match the "Sec" column in the gas flow (in cfh) Table 3, with the time
clocked.
4. Read the "Flow" column opposite the number of seconds clocked.
5. Use the following factors if necessary.
NOTE: For manifold pressures and orifice sizes for gas with
For 1 Cu. Ft. Dial Gas Flow CFH =
For 1/2 Cu Ft. Dial Gas Flow CFH =
For 5 Cu. Ft. Dial Gas Flow CFH =
other BTU ratings, contact the local gas utility. Manifold
pressure should be 1.8 (low) to 3.5 (high) inches water column
(+0.1). Input for natural gas must not exceed the value shown on
the unit nameplate.
6. Multiply the final figure by the heating value of the gas obtained
from the utility company and compare to the nameplate rating.
This must not exceed the nameplate rating.
7. Changes can be made by adjusting the manifold pressure.
Outlet Pressure Boss
Inlet Pressure
Boss
Gas Valve ON/
OFF Toggle High Fire Coil
Switch Terminal (H)
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Chart Flow Reading
2
Chart Flow Reading
4
10X Chart Flow Reading
4
2nd Stage (HI) Manifold
Pressure Adjustment
Regulator Vent
1st Stage (LO)
Manifold
Pressure
Adjustment
Coaxial Coil
Terminal (M)
Common Termi-
nal (C)
Figure 18. Burner and Valve
a. Attach a manifold pressure gauge.
b. Remove the slot screw on top of the gas valve for 1st stage mani-
fold pressure adjustment. Remove slot screw on outlet side for 2nd
stage adjustment (See Figure 18).
c. Turn the adjustment nut in to increase the gas flow rate, and out to
decrease the gas flow rate using a 3/32" hex wrench.
Table 3. Gas Flow in Cubic Feet Per Hour
2 Cubic Foot Dial
Sec. Flow Sec. Flow
8 900 29 248
9 800 30 240
10 720 31 232
11 655 32 225
12 600 33 218
13 555 34 212
14 514 35 206
15 480 36 200
16 450 37 195
17 424 38 189
18 400 39 185
19 379 40 180
20 360 41 176
21 343 42 172
22 327 43 167
23 313 44 164
24 300 45 160
25 288 46 157
26 277 47 153
27 267 48 150
28 257 49 147
Sec. Flow Sec. Flow
50 144 82 88
51 141 84 86
52 138 86 84
53 136 88 82
54 133 90 80
55 131 92 78
56 129 94 76
57 126 96 75
58 124 98 73
59 122 100 72
60 120 104 69
62 116 108 67
64 112 112 64
66 109 116 62
68 106 120 60
70 103 124 58
72 100 128 56
74 97 132 54
76 95 136 53
78 92 140 51
80 90 144 50