Lennox MLDVT-30NM Installation Instructions Manual page 3

Provide adequate clearances around air open-
ings and adequate accessibility clearance for
service and proper operation. Never obstruct
the front openings of the appliance.
These appliances are designed to operate on
natural or propane gas only. The use of other
fuels or combination of fuels will degrade
the performance of this system and may be
dangerous.
These fireplaces are designed as supplemental
heaters. Therefore, it is advisable to have an alter-
nate heat source when installed in a dwelling.
Millivolt Models - The millivolt appliances are
manually controlled and feature a spark igniter
(piezo) that allows the appliance's pilot gas to
be lit without the use of matches or batteries.
This system provides continued service in the
event of a power outage.
Millivolt models come standard with a manu-
ally-modulated gas valve; flame appearance and
heat output can be controlled at the gas valve.
The BTU Input for these appliances is shown
in Tables 1 and 2.
Input (BTU) Manually-Modulated
Gas Valves (all models)
NATURAL GAS
Models Input Rate (BTU / HR)
3,500 high
MLDVT-30N
0,500 low
6,000 high
MLDVT-35N
2,500 low
22,000 high
MLDVT-40N
7,000 low
23,000 high
MLDVT-45N
7,500 low
Table 1
Input (BTU) Manually-Modulated
Gas Valves (all models)
PROPANE GAS
Models Input Rate (BTU / HR)
2,500 high
MLDVT-30P
9,000 low
5,000 high
MLDVT-35P
,500 low
20,000 high
MLDVT-40P
5,800 low
22,000 high
MLDVT-45P
7,000 low
Table 2
Gas Pressure - All Models
Tables 3 and 4 show the appliances' gas
pressure requirements:
Inlet Gas Supply Pressure
(all models)
Fuel # Minimum
4.5" WC
Natural Gas
(.2 kPa)
.0" WC
Propane
(2.74 kPa)
Table 3
Manifold Gas Supply Pressure
(all models)
Fuel # Low
Natural (Lo) 2.2" WC
Gas (0.55 kPa)
(Lo) 6.3" WC (Hi) 0.0" WC
Propane
(.57 kPa)
Table 4
Do not use these appliances if any part has been
under water. Immediately call a qualified, profes-
sional service technician to inspect the appliance
and to replace any parts of the control system and
any gas control which have been under water.
Ne pas se servir de cet appareil s'il a été plongé
dans l'eau, complètement ou en partie. Appeler
un technicien qualifié pour inspecter l'appareil et
remplacer toute partie du système de contrôle et
toute commande qui ont été plongés dans l'leau.
Test gauge connections are provided on the
front of the millivolt and electronic gas control
valve (identified 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.
These appliances must be isolated from the
gas supply piping system (by closing their
individual manual shut-off valve) during any
pressure testing of the gas supply piping
system at test pressures equal to or less
than 1/2 psig (3.5 kPa).
These appliances and their individual
shut-off valves must be disconnected from
the gas supply piping system during any
pressure testing of that system at pressures
greater than 1/2 psig (3.5 kPa).
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.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
These appliances must not be connected to a
chimney or flue serving a separate solid fuel
burning appliance.
Maximum
Orifice Sizes - Sea Level to High Altitude
0.5" WC
(All Models)
(2.6 kPa)
3.0" WC
These appliances are tested and approved for
(3.23 kPa)
installation at elevations of 0-4500 feet (0-1372
meters) above sea level using the standard
burner orifice sizes (marked with an "*" in
Table 5 ). For elevations above 4500 feet,
contact your gas supplier or qualified service
technician .
High
Install the appliance according to the regulations
(Hi) 3.5" WC
of the local authorities having jurisdiction and,
(0.87 kPa)
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.
(2.49 kPa)
Elevation 0-4500 feet ( 0-372 meters)
Model
Series
MLDVT-30
MLDVT-35
MLDVT-40
MLDVT-45
Table 5
Gas Valve Diagrams
See Figure 1 for Millivolt models and Figure 2
For Electronic Models.
Main Gas Control Knob
IN
Manifold Pressure Tap
Inlet Pressure Tap
Figure 1
Burner Orifice Sizes
Nat.Gas Propane
drill size (inches) drill size (inches)
#50 (0.070")* #59 (0.04")*
H4873• H7838
#49 (0.073")* 0.045"*
2L82• 75L0•
#43 (0.089")* #55 (0.052")*
99K75• 9L52•
0.090"* #54 (0.055")*
37L70• 99K79•
* Standard size installed at factory
• Part /Cat. Number
SIT Millivolt Gas Valve
Pilot Adjustment
Screw
OFF/PILOT/ON
OUT
HI/LO Variable
Flame Height
Adjustment
3