Weil-McLain UO-3 CV, Instruction Manual

Page: 8 / 24

8
Exhaust fans and other air-using devices:
Size air
openings large enough to supply all air-using devices
in addition to the minimum size required for combustion
air. If there is any possibility of the equipment room
developing a negative pressure due to exhaust fans,
clothes dryers, etc., either pipe combustion air directly to
the burner or provide a sealed enclosure for the burner
and supply it with its own combustion air supply.
Safety Shutoff for Direct Vent System
The direct vent blocked fl ue safety shut off system, refer
to Figure 3, shuts down the burner if the exhaust fl ue is
blocked and/or if the air inlet is blocked. It recognizes
a blocked
fl ue by sensing excessive pressure in the
combustion chamber. It recognizes a blocked inlet by
sensing excessive vacuum in the air inlet adapter.
This system meets the requirements for a blocked
fl ue or
blocked combustion air inlet per CSA Standard B140.0.
It is designed to interrupt the cad cell circuit and allow
the control to shut down the burner.
Direct/Sidewall Venting Application
For direct vent installations, follow instructions provided
with appliance and direct vent system. Outside
combustion air is required for direct venting.
When installing an NX outside air adapter (Beckett Part
Number 52018U), refer to the instruction sheet supplied
with the adapter. This kit allows combustion air to be
Figure 3. Pressure Switch Installation
piped directly to the burner. The NX outside air adapter
kit may also be used for chimney vent applications that
require outside combustion air.
Mounting dimensions
When using the Beckett universal adjustable fl ange,
mount the air tube at a 2° downward pitch unless
otherwise speci
fi ed by the appliance manufacturer.
Verify that the air tube installed on the burner
provides the correct insertion depth. See Figure 4.
1.
2.
Figure 4. – Mounting Burner in Appliance
SK8745
Tilt down 2°
If space between burner
air tube and opening
exceeds 1/2 inch, pack
burner opening with
ceramic fiber refractory.
Connect Outside Air Duct
to NX Adapter
The outside air adapter must be installed by strictly
following the kit installation instructions.
DO NOT attempt to install outside air piping without
using the outside air adapter and instructions
provided.
Abundant fresh air is required for proper combustion. y
y
y
Failure to install adapter properly could
result in impaired combustion, appliance
soot-up, puffback of smoke, and fi re or
asphyxiation hazards.
Do not attempt to install outside air piping to
the burner without using the outside air kit and
instructions. y
Failure to comply could result in impaired
combustion, appliance soot-up, puffback of smoke,
and fi re or asphyxiation hazards.
Follow the Outside Air Kit
Instructions Exactly
Section: Inspect/Prepare Installation SIte