Instructions / Assembly
Installing Your Furnace
16
Attaching Your Furnace (continued)
After furnace is in position, install rear outlet register as shown in
Figure 12. Have damper in open position when inserting the
assembly. Secure the rear outlet register to speed nuts with the
machine screws furnished.
Gas Supply and Piping
GAS PIPING
The gas supply line must be of adequate size to handle the Btu/hr.
requirements and length of the run for the unit being installed.
Determine the minimum pipe size from Figure 17, basing the
length of the run from the gas meter or source to the unit.
All piping must comply with local codes and ordinances or with the
National Fuel Gas Code (ANSI Z223.1 NFPA No. 54), whichever
applies. (In Canada: CAN/C.G.A B149). Refer to Figure 18 for
the general layout of the unit. It shows the basic fittings needed.
The following rules apply:
1. Use new, properly reamed pipe free from chips such as
steel or black iron pipe and fittings or other approved by
local codes.
2. Do not thread pipe too far. Valve distortion or malfunction
may result from excess pipe within the control. Apply a
moderate amount of good quality dope to pipe only. Leave
the two end threads bare. If L.P. gas installation, use
compound resistant to action of liquefied petroleum gases.
3. Use ground joint unions.
4. Install a drip leg (sediment trap) to trap dirt and moisture
before it can enter the gas valve. The nipple must be a
minimum of 3-inches long.
5. Install a manual shut-off valve.
6. Provide a 1/8 NPT test gauge connection immediately
before the gas supply connection to the furnace.
2509622A Nat. 25,000 18,935 #43 0.089 1
2509621A L.P. 25,000 19,759 .057" 1
3509622A Nat. 35,000 24,496 #36 0.106 1
3509621A L.P. 35,000 25,588 .069" 1
5009622A Nat. 50,000 38,490 .091" 2
5009621A L.P. 50,000 39,827 .058" 2
Furnace Technical Information
Main Burner Orifice
Drill
Decimal
Quantity
Heating
Capacity
Rating
Btu/hr.
Input
Rating
Btu/hr.
Gas
Type
Model
Number
Gas Supply and Piping (continued)
FIGURE 12 – Mounting Rear Outlet Register
The gas control valve, in the furnace, is shipped with a seal over
the gas inlet tapping. Do not remove the seal until ready to
connect the piping.
GAS SUPPLY
For L.P. gas, the minimum inlet gas supply pressure for the
purpose of input adjustment is 11-inches water column. The
maximum inlet gas supply pressure is 13-inches water column.
For natural gas, the minimum inlet gas supply pressure for the
purpose of input adjustment is 5-inches water column. The
maximum inlet gas supply pressure is 7-inches water column.
Gas pressure and input to the burners must not exceed the rated
input and pressure shown on the nameplate. The natural gas
manifold pressure should be 4-inches water column. The
manifold pressure should be 10-inches water column for L.P. gas.
For operation in elevations above 2,000 feet, a burner orifice
change may be required to suit the gas supplied. Check with
your local gas supplier.
ORIFICE SIZES
The efficiency rating of this appliance is a product thermal
efficiency rating determined under continuous operating
conditions and was determined independently of any installed
system. For elevations above 2,000 feet, reduce ratings 4% for
each 1,000 feet above sea level.
WARNING: Danger of property damage, bodily injury or
death. Make sure the furnace is equipped to operate on
the type of gas available. Models designed as natural gas
are to be used with natural gas only. Models designed for
use with liquefied petroleum (L.P) gas have orifices sized
for commercially pure propane gas. They cannot be used
with butane or a mixture of butane and propane.
Gas Conversion Kits
Natural Gas to L.P. Gas
Model
Description
8913
25096A Series with Williams Brand Gas Valve
8914
35096A Series with Williams Brand Gas Valve
8909
50098 Series with Williams Brand Gas Valve
Gas Conversion kits
L.P. Gas to Natural Gas
Model
Description
8915
25096A Series with Williams Brand Gas Valve
8916
35096A Series with Williams Brand Gas Valve
8912
50098 Series with Williams Brand Gas Valve
Furnace Technical Information