Desa VN20BTB Safety Information And Installation Manual page 12

INsTallaTIoN
Continued
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 incoming gas pres-
sure, 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.
CAUTION: Use only new,
black iron or steel pipe. Inter-
nally-tinned copper tubing may
be used in certain areas. Check
your local codes. Use pipe of
large enough diameter to allow
proper gas volume to heater. If
pipe is too small, undue loss of
volume will occur.
Typical Inlet Pipe Diameters
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).
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.
WARNING: Use pipe joint
sealant that is resistant to liquid
petroleum (LP) gas.
Propane/LP
Supply Tank
Figure 14 - External Regulator With Vent
Pointing Down
12
Install sediment trap in supply line as shown
in Figure 15. 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 moisture 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.
IMPORTANT: Hold the pressure regulator
with wrench when connecting it to gas pip-
ing and/or fittings. Do not over tighten pipe
connection to regulator. The regulator body
could be damaged.
Pressure
Regulator
3/8" NPT
Pipe Nipple
External
3/8" NPT/ 1/2"
Regulator
Flare 90° Elbow
with Vent
Pointing
Down
* A CSA design-certified equipment shutoff valve
with 1/8" NPT tap is an acceptable alternative to
test gauge connection. Purchase the optional
CSA design-certified equipment shutoff valve
from your dealer. See Accessories, page 21.
www.desatech.com
Tee Joint
Reducer
Bushing
to 1/8"
NPT
1/8" NPT
Plug Tap
Tee
Joint
From External Regulator
Pipe
Nipple
Refer to
Cap
connector's
instructions
Flexline
Connection Using Flexline
Figure 15 - Gas Connection
Note: Burner
bracket not
shown for clarity
Heater
Cabinet
Ground Joint
Union
Equipment
Shutoff
Valve *
Natural Gas
From Gas Meter
(4" W.C. to
3" Min.
10.5" W.C.
Pressure)
Propane/LP
(11" W.C. to 14" W.C.
Pressure)
See
illustration
above for
detail
121880-01B