Unit Support - Lennox LHT180 Installation Instructions Manual

NOTICE
Roof Damage!
This system contains both refrigerant and oil.
Some rubber roofing material may absorb oil,
causing the rubber to swell. Bubbles in the rubber
roofing material can cause leaks. Protect the roof
surface to avoid exposure to refrigerant and oil
during service and installation. Failure to follow
this notice could result in damage to roof surface.
Use of this unit as a construction heater or air conditioner
is not recommended during any phase of construction.
Very low return air temperatures, harmful vapors and
operation of the unit with clogged or misplaced filters will
damage the unit.
If this unit has been used for heating or cooling of
buildings or structures under construction, the following
conditions must be met or the warranty will be void:
S The vent hood must be installed per these installation
instructions.
S A room thermostat must control the unit. The use of
fixed jumpers that will provide continuous heating or
cooling is not allowed.
S A pre-filter must be installed at the entry to the return
air duct.
S The return air duct must be provided and sealed to
the unit.
S Return air temperature range between 55°F (13°C)
and 80°F (27°C) must be maintained.
S Air filters must be replaced and pre-filters must be
removed upon construction completion.
S The input rate and temperature rise must be set per
the unit rating plate.
S The heat exchanger, components, duct system, air
filters and indoor coil must be thoroughly cleaned
following final construction clean-up.
S The unit operating conditions (including airflow,
cooling operation, ignition, input rate, temperature
rise and venting) must be verified according to these
installation instructions.
This appliance is not to be used by persons with reduced
physical, sensory or mental capabilities, or lack of
experience and knowledge, unless they have been given
supervision or instruction.
This appliance should not be used by children. Children
should be supervised to ensure they do not play with the
appliance.
IMPORTANT
The Clean Air Act of 1990 bans the intentional vent­
ing of refrigerant (CFC's and HCFC's) as of July 1,
1992. Approved methods of recovery, recycling or
reclaiming must be followed. Fines and/or incar­
ceration may be levied for non-compliance.

Unit Support

In downflow discharge installations, install the unit on a
non-combustible surface only. Unit may be installed on
combustible surfaces when used in horizontal discharge
applications or in downflow discharge applications when
installed on an LARMF18/36 roof mounting frame.
NOTE - Securely fasten roof frame to roof per local codes.
CAUTION
To reduce the likelihood of supply / return air by­
pass and promote a proper seal with the RTU, duct
work / duct drops / diffuser assemblies must be
supported independently to the building structure.
A-Downflow Discharge Application
Roof Mounting with LARMF18/36
4- The LARMF roof mounting frame must be installed,
flashed and sealed in accordance with the
instructions provided with the frame.
5- The LARMF roof mounting frame should be square
and level to 1/16" per linear foot (5mm per linear
meter) in any direction.
6- Duct must be attached to the roof mounting frame
and not to the unit; supply and return plenums must
be installed before setting the unit.
Installer's Roof Mounting Frame
Many types of roof frames can be used to install the unit
depending upon different roof structures. Items to keep
in mind when using the building frame or supports are:
1- The base is fully enclosed and insulated, so an
enclosed frame is not required.
2- The frames or supports must be constructed with
non-combustible materials and should be square and
level to 1/16" per linear foot (5mm per linear meter)
in any direction.
3- Frame or supports must be high enough to prevent
any form of
Recommended minimum frame height is 14"
(356mm).
4- Duct must be attached to the roof mounting frame
and not to the unit. Supply and return plenums must
be installed before setting the unit.
Page 5
moisture from entering
508336-01
unit.
1/2023