7
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT PLUS
®
DIRECT VENT GAS FIREPLACES (MPDP35/40) • CARE AND OPERATION INSTRUCTIONS
NOTICE:
A white film may develop
on the glass enclosure panel during
the first few fires as part of the burn-in
process.
The first few times you use the
fireplace, clean the glass after each use
(
AFTER THE GLASS HAS COMPLETELY
COOLED
); otherwise, the white film
will bake onto the glass and become
difficult to remove.
See glass cleaning instructions on
Page 11
.
GENERAL INFORMATION
(continued)
Manifold Gas Supply Pressure
(all models)
Fuel #
Low
High
Natural
Gas
(Lo) 1.6" WC
(0.40 kPa)
(Hi) 3.5" WC
(0.87 kPa)
Propane
(Lo) 6.3" WC
(1.57 kPa)
(Hi) 10.0" WC
(2.49 kPa)
Table 3
BTU Input
These electronic models come standard with a
remotely-modulated gas valve; flame appear-
ance and heat output cannot be controlled at the
gas valve. The BTU Input for these appliances
is shown in
Table 1
.
Burn-in Period
During the first few fires of this appliance there
will be some odor due to the curing of the
paint and burning off of lubricants used in the
manufacturing process. Depending on your
use, the burn-in period may take a few hours
or a few days.
KEEP YOUR HOUSE WELL VENTILATED
DURING THE CURING PROCESS. THE ODOR
AND HAZE EMITTED DURING THE CURING
PROCESS CAN BE QUITE NOTICEABLE AND
MAY SET OFF A SMOKE DETECTOR.
Do not turn on the blower during the burn-in
period.
Test gauge connections are provided on the
front of the electronic gas control valve (identi-
fied IN for the inlet and OUT for the manifold
side). The control valves have a 3/8" (10mm)
NPT thread inlet and outlet side of the valve
(refer to
Figure 1
).
Propane tanks are at pressures that will cause
damage to valve components. Verify that the
tanks have step down regulators to reduce the
pressure to safe levels.
Orifice Sizes - Sea Level to High Altitude
(All Models)
These appliances are tested and approved for
installation at elevations of 0-4500 feet (0-1372
meters) above sea level using the standard burner
orifice sizes (marked with an "*" in
Table 4
).
For elevations above 4500 feet, contact your
gas supplier or qualified service technician.
Deration -
At higher elevations, the amount
of BTU fuel value delivered must be reduced
by either using gas that has been derated by
the gas company or by changing the burner
orifice to a smaller size as regulated by the
local authorities having jurisdiction and by the
(USA) National Fuel Gas Code NFPA 54/ANSI
Z223.1 - latest edition or, in Canada, the CAN/
CSA-B149.1 codes - latest edition.
The appliance and its appliance main gas
valve must be disconnected from the gas
supply piping system during any pressure
testing of that system at test pressures
in
excess of
1/2 psi (3.5 kPa).
The appliance must be isolated from the gas
supply piping system by closing its equipment
shutoff valve during any pressure testing of
the gas supply piping system at test pres-
sures
equal to or less than
1/2 psi (3.5 kPa).
Inlet Gas Supply Pressure
(all models)
Fuel #
Minimum
Maximum
Natural Gas
4.5" WC
(1.12 kPa)
10.5" WC
(2.61 kPa)
Propane
11.0" WC
(2.74 kPa)
13.0" WC
(3.23 kPa)
Table 2
Gas Pressure - All Models
Tables 2 and 3
show the appliances' inlet and
manifold gas pressure requirements:
Install the appliance according to the regulations
of the local authorities having jurisdiction and,
in the USA, the National Fuel Gas Code NFPA
54 / ANSI Z223.1 - latest edition or, in Canada,
the CAN/CSA-B149.1 - latest edition.
Flame breadth, height and width will diminish
4% for every 1,000 feet of altitude.
Figure 1
SIT Proflame Valve
Orange Wire
(From DFC Wire
Harness)
Pressure
Regulator
Tower
Yellow Ground Wire
(From DFC Wire
Harness)
Green Wire
(From DFC Wire
Harness)
Line (In) Test Port
Manifold (Out)
Test Port
Connect GTMS
Wire Harness
Input (BTU/HR) Gas Valves (all models)
Models
Input Rate (BTU / HR)
Nat. Gas
Prop. Gas
MPDP35
25,000
22,000
MPDP40
31,000
29,000
Table 1
Burner Orifice Sizes
Elevation 0-4500 feet ( 0-1372 meters)
Model
Series
Nat.Gas
drill size (inches)
Propane
drill size (inches)
MPDP35
#42 (.093")*
H3721•
#54 (.055")*
99K79•
MPDP40
#36 (.1065")*
18L40•
#52 (.063")*
21L01•
Table 4
* Standard size installed at factory
• Part /Cat. Number
