LAARS Mighty Therm2 MT2V (Sizes 500–2000 MBTU/h) - Install and Operating Manual - Manual (Page 9)

Mighty Therm 2
Page 9
enclosed spaces containing combustion appliances.
Mighty Therm2 units are not allowed to be vented
into a common horizontal vent system, unless a properly
sized vent fan is used, and the common vent system is
properly designed by the vent fan manufacturer or a
qualified engineer.
Refer to the installation and operating instructions
on all appliances to be common vented for instructions,
warnings, restrictions and safety requirements. If safe
operation of all appliances connected to a common vent
cannot be assured, including prevention of spillage of
flue gasses into living spaces, common venting should
not be applied, and appliances should each be vented
separately.
2.2.4 Category III Vent
When the Mighty Therm2 is vented with horizontal
discharge, it must be installed per this installation
manual and the venting system manufacturer’s
installation instructions. The vent system must be sealed
stainless steel ( see Table 5 ).
Route the vent pipe to the heater as directly as
possible. Seal all joints and provide adequate hangers
as required in the venting system manufacturer’s Instal-
lation Instructions. Horizontal portions of the venting
system must be supported to prevent sagging and may
not have any low sections that could trap condensate.
The unit must not support the weight of the vent pipe.
Horizontal runs must slope downwards not less than ¼
inch per foot (2 cm/m) from the unit to the vent terminal.
Reference Table 2 for the size of the Category III vent
system. Up to three elbows can be used with 50 linear
feet (15.2m) of pipe. Subtract 10 allowable linear feet
(3.0m) for every additional elbow used.
WARNING
The outdoor vent terminal gets hot. Unit must be
installed in such a way as to reduce the risk of burns
from contact with the vent terminal.
2.3 Locating Vent & Combustion Air
Terminals
2.3.1 Side Wall Vent Terminal
The appropriate Laars side wall vent hood must
be used, and is listed in the installation and operation
manual. The terminal provides a means of installing
the vent piping through the building wall, and must
be located in accordance with ANSI Z223.1/NFPA 54
and applicable local codes. In Canada, the installation
must be in accordance with CSA B149.1 or .2 and local
applicable codes. Consider the following when installing
the terminal:
1. Figure 4 shows the requirements for mechanical
vent terminal clearances for the U.S. and Canada.
2. Vent terminals for condensing appliances or
appliances with condensing vents are not permitted
to terminate above a public walkway, or over an
area where condensate or vapor could create a
nuisance or hazard.
3. Locate the vent terminal so that vent gases cannot
be drawn into air conditioning system inlets.
4. Locate the vent terminal so that vent gases cannot
enter the building through doors, windows, gravity
inlets or other openings. When possible, locations
under windows or near doors should be avoided.
5. Locate the vent terminal so that it cannot be
blocked by snow. The National Fuel gas code
requires that it be at a minimum of 12" above
grade. In a location that has the possibility of snow
accumulation, it is critical the installer places the
vent at least 12" higher than the maximum potential
snow line. Seek local municipalities and their codes
for appropriate installation techniques.
6. Locate the terminal so the vent exhaust does not
settle on building surfaces or other nearby objects.
Vent products may damage such surfaces or
objects.
7. If the boiler or water heater uses ducted combustion
air from an intake terminal located on the same
wall, locate the vent terminal at least 3 feet (0.9m)
horizontally from the combustion air terminal, and
locate the vent terminal at least 1 foot (0.3m) above
the combustion air terminal.
2.3.2 Side Wall Combustion Air Terminal
The Laars side wall combustion air terminal (see
Table 2 ) must be used when the unit takes its combustion
air through a duct from a side wall. Consider the
following when installing the terminal:
1. Do not locate the air inlet terminal near a source
of corrosive chemical fumes (e.g., cleaning fluid,
chlorinated compounds, etc.)
2. Locate the terminal so that it will not be subject to
damage by accident or vandalism.
3. Locate the combustion air terminal so that it
cannot be blocked by snow. The National Fuel
gas code requires that it be at a minimum of 12"
above grade. Depending on local conditions, the
installer should ensure that it remains at least 12"
above the maximum potential snow line. Seek
local municipalities and their codes for appropriate
installation techniques.
WARNING: It is critical that the combustion
air intake and the vent terminals remain at least
12" above the maximum potential snow line.
If either the vent terminal or the air terminal is
blocked by snow, there may be potential for the
unit to produce excess carbon monoxide and or
recirculate flue gasses into the building/dwelling.
TERM DESCRIPTION
Pipe Must comply with UL Standard 1738
such as Type 29-4C Stainless Steel
(either insulated or non-insulated).
Joint Follow vent manufacturer’s instructions
Sealing
Table 5. Required Horizontal Venting Material.