Owner’s manual, Installation, Continued) – Williams 4003532 User Manual
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OWNER’S MANUAL
Providing Gas Piping to Furnace
You must provide gas piping from gas source to furnace. The gas piping must be in a vertical
position where it connects to the furnace. This prevents interference with front cover
installation.
Consult your local gas company for proper routing of the gas lines.
Pipe size is determined by the length of pipe from the gas source to the furnace and the total
BTU load on the gas source.
Add the total BTUs required for all appliances connected to the gas source including this furnace.
Divide this number by 1030. This will give you the approximate cubic feet per hour needed.
Example:
40,000 BTU/Hr
+ 15,000 BTU/Hr for other gas appliances
55,000 BTU/Hr total
55,000
÷
1030 = 53.4
Locate 53.4 or higher on chart below.
According to the chart below, you should use 50 feet or less of 1/2" pipe, 200 feet
or less of 3/4" pipe, etc...
MINIMUM
IRON PIPE
SIZE
LENGTH OF PIPE (FEET)
10
20
30
40
50
60
70
80
90
100
125
150
175
200
3/8"
72
49
40
34
30
27
25
23
22
21
18
17
15
14
1/2"
132
92
73
63
56
50
46
43
40
38
34
31
28
26
3/4"
278
190
152
130
115
105
96
90
84
79
72
64
59
55
1"
520
350
285
245
215
195
180
170
160
150
130
120
110
100
1
1
/
4
"
1050
730
590
500
440
400
370
350
320
305
275
250
225
210
1
1
/
2
"
1600
1100
890
760
670
610
560
530
490
460
410
380
350
320
2"
3050
2100 1650 1450 1270 1150 1050
990
930
870
780
710
650
610
2
1
/
2
"
4800
3300 2700 2300 2000 1850 1700 1600 1500 1400 1250 1130 1050
980
3"
8500
5900 4700 4100 3600 3250 3000 2800 2600 2500 2200 2000 1850 1700
4" 17500 12000 9700 8300 7400 6800 6200 5800 5400 5100 4500 4100 3800 3500
IMPORTANT:
Check gas line pressure at gas meter before connecting furnace to gas line. Gas
line pressure must be no less than 5 inches of water and no greater than 7 inches of water. Gas
pressures and input to the burners must not exceed the rated input and pressure shown on the
rating plate. For natural gas, manifold pressure should be 3.5 inches of water. For elevations
above 2000 feet, reduce rating 4% for each 1000 feet above sea level (U.S.A. only).
INSTALLATION
(Continued)
Continued