Suburban SA25N Owner's Operation And Installation Manual page 4

10. 25,000 BTU/Hr Model: Replace two
INSTALLATION
screws removed in step 2. Attach fur-
(Continued)
nace flange and furnace cabinet
lower flange together.
Connecting Furnace to Gas
40,000 BTU/Hr Model: Place bottom
Supply at Front of Furnace
shield back in place. Replace two
screws removed in step 2. Attach bot-
1. Locate gas inlet pipe on lower, right
tom shield, furnace flange, and
front of furnace (see Figure 8).
furnace cabinet lower flange together.
2. Connect 3/8" NPT pipe or nipple to
11. Run 3/8" pipe or nipple through
gas inlet pipe (see Figure 8). See
knockout hole. Connect 3/8" pipe or
Providing Gas Piping to Furnace for
nipple to manifold elbow (see Figure
correct gas pipe installation.
14). See Providing Gas Piping to
Furnace for correct gas pipe instal-
lation.
CAUTION: Lightly apply pipe joint
sealant to male threads before
connecting. Use pipe joint sealant
that is resistant to liquid petroleum
(LP) gas.
12. Check connections for gas leak.
Figure 8 - Connecting Gas from Inside of
WARNING: Never use an open
Room
flame to check for a leak. Apply a
mixture of liquid soap and water to
all joints. Bubbles forming show a
Connecting Furnace to Gas
leak. Correct all leaks at once.
Supply at Rear of Furnace
13. Caulk around pipe or nipple. This pre-
1. Remove the two screws in back of fur-
vents cold air entering knockout hole.
nace cabinet located by the exhaust
vent(s) (see Figures 9 and 10).
2. Remove two screws on front lower
flange that attach furnace flange to
furnace cabinet flange (see Figure
11). Note: 40,000 BTU/Hr model has
a bottom shield (see parts list, page
19, for location). Removing two
screws will detach bottom shield.
3. Slide furnace out of furnace cabinet.
4. Locate gas inlet pipe on lower, right
front of furnace.
Figure 9 - Locations of Screws in Back
5. 40,000 BTU/Hr Model Only: Remove
of Furnace Cabinet (25,000 BTU/Hr
screw holding gas inlet pipe clamp to
Model)
furnace. (See Figure 12).
6. Disconnect gas inlet pipe from 3/8"
manifold elbow. Turn gas inlet pipe
counterclockwise to disconnect (see
Figure 12).
7. Rotate the 3/8" manifold elbow 90 so
the opening is pointing downward
(see Figure 12).
8. Locate knockout plug in furnace cabi-
net. Knockout plug is in lower left rear
of furnace cabinet (as viewed from
rear, see Figure 13). Remove
knockout plug.
Figure 10 - Locations of Screws in
Back of Furnace Cabinet (40,000
9. Slide furnace back into furnace cabi-
BTU/Hr Model)
net. Make sure exhaust tube gaskets
are in place. Make sure exhaust and
intake vent tubes extend into vent
caps on back of cabinet. Replace two
screws by exhaust vent(s) removed in
step 1.
Figure 11 - Removing Screws on Lower
Flange (40,000 BTU/Hr Model Shown)
Figure 12 - Disconnecting Gas Inlet Pipe
(40,000 BTU/Hr Model Shown)
Figure 13 - Location of Knockout Plug
Figure 14 - Inserting Pipe through
Knockout Hole
7
INSTALLATION
(Continued)
Providing Gas Piping to Furnace - Propane (LP) Gas Only
See Next Page for Natural Gas Piping
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 2500. 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 ÷ 2500 = 22
Locate 22 or higher on chart below.
According to the chart below, you should use 40 feet or less of 3/8" pipe, 125 feet
or less of 1/2" pipe, etc....
MINIMUM
RON PIPE
SIZE
10 20 30 40 50
47 32 26 22 19
3/8"
1/2" 87 61 48 42 37
3/4" 184 126 100 86 76
1" 344 232 189 162 142 129
696 484 391 331 291 265
1¼"
1½" 1060 729 590 504 444 404
2" 2022 1392 1094 961 842 762
2½" 3182 2188 1790 1524 1326 1226
5635 3911 3116 2718 2387 2154
3"
11602 7956 6431 5503 4906 4508
4"
IMPORTANT: Check gas line pressure at gas meter before connecting furnace to gas line. Gas line pressure must be no less than
11 inches of water and no greater than 13 inches of water. Gas pressures and input to the burners must not exceed the rated input
and pressure shown on the rating plate. For propane/LP gas, manifold pressure should be 10 inches of water. For elevations above
2000 feet, reduce rating 4% for each 1000 feet above sea level (U.S.A. only).
CAUTION: Never connect heater directly to the propane/LP supply. This heater requires an external regulator (not
supplied). Install the external regulator between the heater and propane/LP supply.
The installer must supply an external regulator. The external regulator will reduce incoming gas pressure. You must reduce incoming
gas pressure to between 11 and 14 inches of water. If you do not reduce incoming gas pressure, heater regulator damage could
occur. Install external regulator with the vent pointing down. Pointing the vent down protects it from freezing rain or sleet.
LENGTH OF PIPE (FEET)
60 70 80 90 100 125 150 175
18 16 15 14 13 12 11 10
33 30 28 26 25 22 20 18
69 63 59 55 52 48 42 39
119 112 106 99 86 79 73
245 232 212 202 182 166 149
371 351 324 305 272 252 232
696 656 616 576 517 470 430
1127 1060 994 928 829 749 969
1989 1856 1724 1657 1458 1326 1226
4110 3845 3580 3381 2983 2718 2519
8
200
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17
36
66
139
212
404
649
1127
2320