Connect The Gas Line - Superior Fireplaces MHD 35 Series Installation And Operation Instructions Manual

Innovative Hearth Products
MHD 35/40 Series Direct-Vent Gas Fireplaces
Figure 34 - Junction Box Wiring, 120 V, 60 hz, 1 phase
Plug blower into
this receptacle

Connect the Gas Line

14.
All codes require a shutoff valve mounted in the supply line. Figure 37 illustrates two methods for connecting the
gas supply. The flex-line method is acceptable in the U.S., however, Canadian requirements vary depending on
locality. Installation must be in compliance with local codes.
NOTE: Ensure the CPI/IPI switch is set to intermittent mode with the pilot in the OFF position. See control
compartment door label for more information.
NOTE: A sediment trap is recommended in the gas piping within the home to prevent moisture and debris in the line
from damaging the valve.
NOTE: Secure all joints tightly using appropriate tools and sealing compounds (ensure propane resistant compounds
are used in propane applications). Seal around the gas line to prevent cold air leakage. Gas line holes and other
openings can be caulked or stuffed with unfaced fiberglass insulation.
Figure 36 - Control Compartment
Main gas shutoff
valve
Optional burner ON/OFF switch (millivolt units)
CPI/IPI switch (electronic units)
These fireplaces are equipped with a gas flex line for use (where permitted) in connecting the unit to the gas line. A
gas flex line is provided to aid in attaching the direct-vent fireplace to the gas supply. The gas flex line can only be
used where local codes permit. The flex line is rated for both natural and propane gas. A manual shut off valve is also
provided with the flex line.
The gas control valve is located in the lower control compartment (Figure 36).
Access the Control Compartment
See Page 52 for instructions on Accessing the Control Compartment.
Millivolt and electronic control valves have a 3/8" (10 mm) NPT thread inlet port.
* Wall-mounted ON/
OFF blower switch
or variable speed
control switch
Junction
box
Hot side of
Red receptacle
Black
Neutral side
of receptacle
Tab
Green ground screw
intact
Blower
Field wired
Factory wired
Ground
Gas valve
Figure 35 - Wiring Diagram—
APPLIANCE- MOUNTED
ON/OFF SWITCH
(OPTIONAL)
BK/W(1)
WALL-MOUNTED ON/OFF SWITCH (OPTIONAL)
THERMOSTAT (OPTIONAL)
Tab
broken
WALL MOUNTED CONFIGURATION FOR FAN SWITCH (OPTIONAL)
FAN
(OPTIONAL)
Piezo
(millivolt units) Door latch
Millivolt Gas Valves
THERMOPILE
TP-TH
TP
TH
GAS VALVE
BK/W(1)
BK
R
W
GR
JUNCTION BOX
Figure 37 - Gas Line Connection
3/8 NPT x 3/8"
Gas
Flare fitting
valve
3/8" Flex tubing
(Optional) flexible gas
line connector
3/8" Nipple
3/8" Union
3/8" Close nipple
3/8" Shutoff valve
Installation
900414-00 12/2015
1/2 x 3/8" Flare
shutoff valve
Gas
stub
1/2 x 3/8"
Reducer
39