Desa GWN20TB Safety Information And Installation Manual page 12

CONNECTING TO GAS SUPPLY
WARNING: This appliance
requires a 3/8" NPT (National
Pipe Thread) inlet connection to
the pressure regulator.
WARNING: A qualified ser-
vice person must connect heater
to gas supply. Follow all local
codes.
WARNING: For natural
gas, never connect heater to
private (non-utility) gas wells.
This gas is commonly known
as wellhead gas.
IMPORTANT: For natural gas, check gas line
pressure before connecting heater to gas line.
Gas line pressure must be no greater than
10.5" of water. If gas line pressure is higher,
heater regulator damage could occur.
CAUTION: For propane/LP
gas, never connect heater directly
to the propane/LP supply. This
heater requires an external regu-
lator (not supplied). Install the
external regulator between the
heater and propane/LP supply.
For propane/LP gas, 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" of water. If you do not reduce incom-
ing gas pressure, heater regulator damage
could occur. Install the external regulator with
the vent pointing down as shown in Figure
14. Pointing the vent down protects it from
freezing rain or sleet.
12
INsTallaTIoN
Continued
iron or steel pipe. Internally-tinned
copper tubing may be used in
certain areas. Check your local
codes. Use pipe of large enough
diameter to allow proper gas vol-
ume to heater. If pipe is too small,
undue loss of volume will occur.
20,000 Btu/Hr Models - 3/8" or greater
30,000 Btu/Hr Models - 1/2" or greater
Installation must include equipment shutoff
valve, union and plugged 1/8" NPT tap. Locate
NPT tap within reach for test gauge hook up.
NPT tap must be upstream from heater (see
Figure 15, page 13).
IMPORTANT: Install an equipment shutoff
valve in an accessible location. The equip-
ment shutoff valve is for turning on or shutting
off the gas to the appliance.
Apply pipe joint sealant lightly to male NPT
threads. This will prevent excess sealant from
going into pipe. Excess sealant in pipe could
result in clogged heater valves.
sealant that is resistant to liquid
petroleum (LP) gas.
Install sediment trap in supply line as shown
in Figure 15, page 13. Locate sediment trap
where it is within reach for cleaning. Locate
sediment trap where trapped matter is not
likely to freeze. A sediment trap traps mois-
ture and contaminants. This keeps them from
going into heater controls. If sediment trap is
not installed or is installed wrong, heater may
not run properly.
Propane/LP
Supply Tank
Figure 14 - External Regulator With Vent
www.desatech.com
CAUTION: Use only new, black
Typical Inlet Pipe Diameters
WARNING: Use pipe joint
Pointing Down
External
Regulator
With Vent
Pointing
Down
124002-01C