Page 3
ML180UHT Gas Furnace
The ML180UHT unit is shipped ready for installation in the
upflow or horizontal right position (for horizontal left posi
tion the combustion air pressure switch must be moved).
The furnace is shipped with the bottom panel in place. The
bottom panel must be removed if the unit is to be installed in
a horizontal application. The panel may also be removed in
upflow applications with bottom return air.
Shipping and Packing List
Package 1 of 1 contains
1 - Assembled ML180UHT unit
1 - Bag assembly containing the following:
2 - Screws
1 - Snap bushing
1 - Snap plug
1 - Wire tie
1 - Vent warning label
1 - Owner's manual
The following items may be ordered separately:
1 - Thermostat
1 - Suspension kit (for horizontal installations)
1 - Propane/LP changeover kit
1 - Return air base
1 - High altitude kit
1 - Side filter kit
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Requirements
The ML180UHT furnace is approved for installation for in
side of building only, with clearances as listed in figure 6.
(Accessibility and service clearances must take prece
dence over fire protection clearances). Installation of Len
nox forced air central furnaces must be in accordance with
these instructions, local gas fitting regulations, municipal
building codes and electrical wiring regulations
The acceptable natural gas Wobbe number values for use
with Lennox furnaces are shown in Table 1.
TABLE 1
Wobbe
Number*
Min
Normal
Max
46.95 mj / m
3
(1260 Btu / ft
3
)
50.15 mj / m
3
(1346 Btu / ft
3
)
53.28 mj / m
3
(1430 Btu / ft
3
)
Gas Properties 101.3 kPa, 15° C Dry bulb
(14.73 psia, 60° F Dry Bulb)
* Wobbe number = heating value
square root of specific
gravity
If you need to know whether a gas is acceptable, request
the Wobbe number from your gas supplier and compare to
the chart. If the number is within the ranges listed for Natu
ral gas, the gas is acceptable to use. If the Wobbe number
is outside the acceptable ranges, the gas is not acceptable
to use.
As LP (Propane) is a regulated/manufactured gas, a
Wobbe number is not required to determine acceptability.
For propane installations, the acceptable heating value
range is 93.2 mj / m
3
(2500 btu/ft
3
) +/- 5%.
NOTE -
Lennox does not recommend using unrefined or
”well head” gas on Lennox gas-fired furnaces. The quality
of gas is not controlled and may have contaminants which
may lead to corrosion, premature heat exchanger failure or
may void the equipment warranty. The information pro
vided above is intended for evaluating fuel gases available
commercially through gas utilities or LP (propane) suppli
ers.
Adequate clearance must be made around the air open
ings into the vestibule area. Provisions shall be made for
proper operation and for combustion air and ventilation air
supply according to local codes or these instructions.
NOTE -
For installation on combustible floors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.
For installation in a residential garage, the furnace must be
installed so that the burner(s) and the ignition source are
located no less than 457 mm (18 in) above the floor. The
furnace must be located or protected to avoid physical
damage by vehicles. When a furnace is installed in a public
garage, hangar, or other building that has a hazardous at
mosphere, the furnace must be installed according to local
codes.
Unit must be adjusted to obtain a temperature rise within
the range specified on appliance rating plate.
This ML180UHT furnace must be installed so that its elec
trical components are protected from water.
When this furnace is used with cooling units, it shall be
installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment.
With a parallel flow arrangement, a damper (or other
means to control the flow of air) must adequately prevent
chilled air from entering the furnace. If the damper is manu
ally operated, it must be equipped to prevent operation of
either the heating or the cooling unit, unless it is in the full
HEAT
or
COOL
setting.
When installed, this furnace must be electrically
grounded according to local codes.
