Design Dynamics VF-18N-MHD Gas Heater User Manual


 
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116986-01H 13
where trapped matter is not likely to freeze.
A sediment trap traps moisture and contami-
nants. This keeps them from going into heater
controls. If sediment trap is not installed or is
installed wrong, heater may not run properly.

    


CHECKING GAS CONNECTIONS

and connections, internal and
external to unit, for leaks after


WARNING: Never use an

-



CAUTION: Make sure exter-

  
-
der Connecting to Gas Supply,



      

1. Disconnect appliance with its appliance
main gas valve (control valve) and equip-
ment shutoff valve from gas supply piping
system. Pressures in excess of 1/2 psig
will damage heater regulator.
2. Cap off open end of gas pipe where equip-
ment shutoff valve was connected.
3. Pressurize supply piping system by either
opening propane/LP supply tank valve
for propane/LP gas or opening main gas
valve located on or near gas meter for
natural gas or using compressed air.
INSTALLATION
Continued
Installation must include an 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 12).
IMPORTANT: Install equipment shutoff valve
in an accessible location. The equipment
shutoff valve is for turning on or shutting off
the gas to the appliance.
Check your building codes for any special
requirements for locating equipment shutoff
valve to replaces.
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.
    


We recommend that you install a sediment
trap in supply line as shown in Figure 12.
Locate sediment trap where it is within reach
for cleaning. Install in piping system between
fuel supply and heater. Locate sediment trap
* Purchase the optional equipment shutoff
valve from your dealer. See Accessories,
page 25.
** Minimum inlet pressure for purpose of input
adjustment.
Figure 12 - Gas Connection
3" Minimum
Equipment Shutoff Valve
With 1/8" NPT Tap*
Approved
Flexible Gas
Hose (if allowed
by local codes)
Cap Pipe Tee
Nipple Joint
Sediment Trap
Natural Gas
From Gas Meter
(5" W.C.** to 10.5"
W.C. Pressure)

From External
Regulator
(11" W.C.** to
14" W.C.
Pressure)
To Gas
Control