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AQ252 Universal Injection/Mixing Boiler Reset Control Panels
Temperature Sensor Wiring
Connect the lead wires of each sensor to the corresponding
terminals on top of the AQ1520 Control Module. See Fig. 5.
The Boiler Supply, Return and Secondary loop sensors can be
installed either as strap-on sensors or inserted into an
immersion well that is packed with thermally-conductive paste.
BOILER SUPPLY AND RETURN SENSORS.
Both the Supply and Return Sensors should be installed on the
supply and return piping of the boiler for proper operation of
the AQ252 Control Panel. Even if the AQ252 is connected to a
modulating condensing boiler with its own supply and/or return
sensors, the AQ252's sensors should still be installed for the
control to operate.
The Boiler Supply water sensor should be installed on the
supply piping close to the exit port of the boiler, using one of
the AQ12C11 strap-on sensors supplied with the AQ252. See
Fig. 6 on page 8.
The Boiler Return sensor should be installed on the return
piping as close to the entrance port to the boiler as practical,
using the other AQ12C11 strap-on sensor supplied with the
AQ252.
The correct location is one that will measure the temperature of
all combined sources of water returning back to the boiler.
Insulate strap-on sensors with pipe wrap to ensure accurate
boiler temperature sensing.
The Boiler Supply and Return water sensors come with 10 ft.
(3m) of wire to minimize the need for splicing.
69-1986—02
Fig. 5. Low voltage wiring for the AQ15200B Control Module.
SECONDARY (MIXED) LOOP SUPPLY SENSOR
The secondary sensor should be installed on the secondary
(mixed) water piping, far enough downstream of the mixing
device that the return water from the mixed loop and the boiler
loop water are sufficiently well mixed, but before it flows
through a branch leading to a zoning pump, zoning valve or
manifold. The sensor used for the secondary loop is the same
type of sensor (AQ12C11) as the Boiler Supply and Return
sensors. See Fig. 6.
Fig. 6. Strap-on temperature sensor installation.
OUTDOOR SENSOR
The outdoor sensor should be located:
• in a shady location out of direct sunlight
• at least three feet from dryer, bathroom, or other vents
• above the expected snow line where ice and debris cannot
cover it
• on the north side of the building.
See Fig. 7 on page 9 for typical placement. Outdoor sensor
comes with 10 ft. (3m) of wire to facilitate splicing the sensor on
the interior of the building. Alternatively, if the building is
equipped with a continuous fresh air supply using, for example,
an air-to-air heat exchanger, the outdoor sensor may be
installed in the insulated portion of the ventilation intake duct,
taking care not to expose the sensor to direct or indirect
sunlight.
8
M27685A
M13763
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