15
PIPE INSTALLATION
1. Install the gas piping in accordance with applicable
local codes.
2. Check gas supply pressure. Each duct furnace must
be connected to a manifold pressure and a gas
supply capable of supplying its full rated capacity as
specifi ed in Table 5. A fi eld LP tank regulator must
be used to limit the supply pressure to a maximum
of 14" W.C. (3.5 kPa). All piping should be sized
in accordance with the latest edition of ANSI
Standard Z223.1, National Fuel Gas Code; in
Canada, according to CGA B149. See Tables 1, 4
& 5 (of this manual) for correct gas piping size. If gas
pressure is excessive on natural gas applications,
install a pressure regulating valve in the line
upstream from the main shutoff valve.
3. Adequately support the piping to prevent strain on
the gas manifold and controls.
4. To prevent the mixing of moisture with gas, run the
take-off piping from the top, or side, of the main.
5. Duct furnaces are shipped with a combination valve
which includes:
a. Manual "A" valve
b. Manual "B" valve
c.
Solenoid
valve
d.
Pilot
safety
e.
Pressure
regulator
Pipe directly into the combination valve (see Figure
10).
6. A 1/8" N.P.T. plugged tapping, accessible for test
gauge connection, must be installed immediately
upstream of the gas supply connection to the
appliance.
7. Provide a drip leg in the gas piping near the gas duct
furnace. A ground joint union and a manual gas
shutoff valve should be installed ahead of the unit
heater controls to permit servicing. The manual
shutoff valve must be located external to the jacket
(See Figure 10).
8. Make cer tain that all connections have been
adequately doped and tightened.
Do not over tighten the inlet gas piping
into the valve. This may cause stresses that will crack
the valve!
NOTICE: Use pipe joint sealant resistant to the action
of liquefied petroleum gases regardless of gas
conducted.
Check all pipe joints for leakage
using a soap solution or other approved method.
Never use an open fl ame or severe personal injury
or death may occur!
Gas Type
Manifold
Pressure
Supply Inlet
Pressure
Natural Gas
3.5 in. W.C.
(0.9 kPa)
14 in. W.C. Max.
(3.5 kPa)
5.5 in W.C. Min.
(1.4 kPa)
Propane (LP) Gas
10.5 in. W.C.
(2.6 kPa)
14 in. W.C. Max.
(3.5 kPa)
13.0 in W.C. Min.
(3.2 kPa)
*For single stage applications only at normal altitudes.
D3631C
Figure 10- Pipe Installation, Standard Controls
Never use an open fl ame to detect
gas leaks. Explosive conditions may exist which
will result in personal injury or death.
The appliance and its individual shutoff valve must be
disconnected from the gas supply piping system during
any pressure testing of that system in excess of 1/2 psig
(3.5 kPa).
The appliance must be isolated from the gas supply piping
system by closing its individual manual shutoff valve
during any pressure testing of the gas supply piping
system at test pressures equal to or less than 1/2 psig
(3.5 kPa).
Table 5 - Gas Requirements*
