LAARS Mighty Therm2 MT2P (Sizes 500–2000 MBTU/h) - Install and Operating Manual - Manual (Page 9)

MT2P Pool Heater Page 9
Canada, from CSA B149.1 as well as all applicable
local codes, it is required that installers provide some
means to prevent operation with a blocked common
vent. It is suggested that a blocked vent safety system
be employed such that if the switch from one appliance
trips due to excessive stack spill or backpressure
indicating a blocked vent condition, that all appliances
attached to the vent be locked out and prevented
from operating. (Note that the MT2P Pool Heater
is equipped with a blocked vent safety (pressure)
switch, as shipped.) As an additional precaution, it is
recommended that a Carbon Monoxide (CO) alarm be
installed in all enclosed spaces containing combustion
appliances. If assistance is required in determining
how a blocked vent safety system should be connected
to a LAARS product, please call Laars' Applications
Engineering Dept.
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 MT2P 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, per 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
Installation 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 1 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.
2.3 Locating Vent & Combustion Air
Terminals
2.3.1 Side Wall Vent Terminal
The Laars side wall vent hood ( listed in Table
1 ) must be used when the heater is vented through a
side wall. It provides a means of installing 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 CAN/CGA B149.1 or .2 and local
applicable codes ( see Figure 3 ). Consider the following
when installing the terminal:
1. Through-the-wall vent terminals must terminate at
least 7-feet above a public walkway.
2. Locate the vent terminal so that vent gases cannot
be drawn into air conditioning system inlets. The
National Fuel Gas Code requires that it be at least
3 feet (0.9m) above any such inlet
that is within a horizontal distance of 10 feet (3m).
3. Locate the vent terminal so that vent gases cannot
enter the building through doors, windows, gravity
inlets or other openings. The National Fuel Gas
Code requires that it be located at least 4 feet
(1.2m) below, 4 feet (1.2m) horizontally from,
or 1 foot (0.3m) above such openings. Whenever
possible, locations under windows or near doors
should be avoided.
4. Locate the vent terminal so that it cannot be
blocked by snow. The National Fuel Gas Code
requires that it be at least 12 inches (30 cm) above
grade, but the installer may determine it should be
higher, depending upon local conditions.
5. Locate the terminal so the vent exhaust does
not settle on building surfaces and other nearby
objects. Vent products may damage such surfaces
or objects.
6. Locate the terminal at least 6 feet (1.8m)
horizontally from any gas or electric metering,
regulating, or relief equipment.
7. If the MT2P 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.
8. Note that side wall vent terminals for all models
are shipped with reducers for the vent collars,
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.
OUTDOOR VENT OUTDOOR
SIZE TERMINAL COMBUSTION
AIR TERMINAL
500 20254703 D2007900
750 20254705 D2007900
1000 20254705 D2008000
1250 D2007700 D2008000
1500 D2007700 D2008000
1750 D2007800 D2008000
2000 D2007800 D2008200
Table 6. Vent Terminals for Outdoor Units.