Installation
900414-00 12/2015
Innovative Hearth Products
MHD 35/40 Series Direct-Vent Gas Fireplaces
39
Figure 34 - Junction Box Wiring, 120 V, 60 hz, 1 phase
Figure 35 - Wiring Diagram—
Millivolt Gas Valves
Ground: green Neutral: white 120 V
AC: black
Wall-mounted ON/
OFF blower switch
or variable speed
control switch
*
Junction
box
Tab
broken
Hot side of
receptacle
Neutral side
of receptacle
Green ground screw
Tab
intact
Field wired
Factory wired
Blower
Ground
Plug blower into
this receptacle
Red
Black
Green
White
TP-TH
TP
TH
APPLIANCE- MOUNTED
ON/OFF SWITCH
(OPTIONAL)
BK/W(1)
BK/W(1)
WALL-MOUNTED ON/OFF SWITCH (OPTIONAL)
THERMOSTAT (OPTIONAL)
JUNCTION BOX
BLAC
K
W
GR
120
V
AC
WALL MOUNTED CONFIGURATION FOR FAN SWITCH (OPTIONAL)
BK
R
THERMOPILE
GAS VALVE
FAN
(OPTIONAL)
14.
Connect the Gas Line
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
Figure 37 - Gas Line Connection
Main gas shutoff
valve
Gas valve
Optional burner ON/OFF switch (millivolt units)
CPI/IPI switch (electronic units)
Piezo
(millivolt units) Door latch
(Optional) flexible gas
line connector
Gas
valve
3/8” Nipple
3/8” Union
3/8” Close nipple
3/8” Shutoff valve
3/8 NPT x 3/8”
Flare fitting
1/2 x 3/8” Flare
shutoff valve
3/8” Flex tubing
Gas
stub
1/2 x 3/8”
Reducer
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.