LAARS Mighty Therm LO-NOx PW (Sizes 500-1825) - Install and Operating Manual - Manual (Page 6)

LAARS HEATING SYSTEMS Page 6
4. Avoid terminating heater vents near air
conditioning or air supply fans. The fans can
pick up exhausted flue products from the heater
and return them inside the building creating a
possible health hazard. A minimum of 4 feet
(1.2m) horizontal distance must be maintained
from electrical meters, gas meters, and relief
equipment.
5. Always use double-wall or insulated vent pipe
(Type B or equivalent). In cold weather,
uninsulated outside vents can chill the rising flue
products blocking the natural draft action of the
venting systems. This can create a health hazard
by spilling flue products in the heater room.
6. Avoid oversized vent piping or extremely long
runs of pipe which may cause excessive cooling
and condensation. Rule of Thumb: the total
length of the vent, including the connector and
any offset, should not exceed 15 feet (4.6m) for
every inch (25mm) of vent diameter. Longer
total lengths shown in venting tables are based
on maximum capacity, not condensation factors.
7. When the installation of a draft fan is necessary
in connecting a venting system to a Laars heater,
the installation should be engineered by
competent personnel following good engineering
practices. The draft fan supplier should be
consulted for correct size. The installation
should be in accordance with the latest edition of
ANSI Z223.1 and/or, in Canada, CAN/CGA B-
149 and any local codes having jurisdiction.
When a draft fan is installed, a suitable draft
switch must be wired into the boiler control
circuit at terminal designated "Field Interlock"
to prevent firing of the boiler unless a positive
draft has been established.
2.2.3 Removal of Existing Heater
At the time of removal of an existing heater, the
following steps shall be followed with each appliance
remaining connected to the common venting system
placed in operation, while the other appliances
remaining connected to the common venting system
are not in operation.
1. Seal any unused openings in the common
venting system.
2. Visually inspect the venting system for proper
size and horizontal pitch and determine that
there is no blockage or restriction, leakage,
corrosion or other deficiencies which could
cause an unsafe condition.
3. Insofar as is practical, close all building doors
and windows, as well as all doors between the
space in which the appliances remaining
connected to the common venting system are
located and other spaces of the building. Turn on
clothes dryers and any appliance not connected
to the common venting system. Turn on any
exhaust fans, such as range hoods and bathroom
exhausts so they will operate at maximum speed.
Do not operate a summer exhaust fan. Close
fireplace dampers.
4. Place in operation the appliance being inspected.
Follow the lighting instructions. Adjust
thermostat so appliance will operate
continuously.
5. Test for spillage at the draft hood relief opening
(if the appliance is equipped with a drafthood),
after 5 minutes of main burner operation. Use the
flame of a match or candle, or smoke from a
cigarette, cigar or pipe.
6. After it has been determined that each appliance
remaining connected to the common venting
system properly vents when tested as outlined
above, return door, windows, exhaust fans,
fireplace dampers and any other gas-burning
appliances to their previous condition of use.
7. Any improper operation of the common venting
system should be corrected so the installation
conforms with the National Fuel Gas Code,
ANSI Z223.1. When resizing any portion of the
common venting system, the common venting
system should be resized to approach the
minimum size as determined using the
appropriate Tables in Appendix G in the
National Fuel Gas Code, ANSI Z223.1.
In Canada, at the time the boiler is removed from
common venting system, the common venting system
should be resized so the installation conforms to CAN/
CGA B149.1 or .2.
2.3 Installation of Outdoor Heaters
(Not available in Canada)
1. Locate the heater to provide the clearances as
listed in Table 1, “Minimum Heater Clearances.”
2. Do not place the heater in an enclosure or wall
recess. Avoid locations where wind deflection
off structures might cause downdraft. When such
wind conditions are possible, place the heater at
least 3 feet (0.9m) from the structures.
3. Never install the heater under any kind of roof
overhang. Do not place the heater below or
adjacent to any doors, windows, louvers, grills,
etc., which connect in any way with an inhabited
area of a building. This includes other structures
such as garages or utility rooms (see Figure 5).
4. Although the Laars models are CSA designed
certified for outdoor installations, such
installations are not recommended in areas where
the danger of freezing exists unless proper
precautions are taken for freeze protection.
Outdoor installations are not recommended in
areas where the danger of snow blockage exists.