Honeywell AQ25A Series Technical Reference Booklet page 13

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
AQ25A.
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.
Fig. 6. Strap-on temperature sensor installation.
OUTDOOR SENSOR: FOR USE WITH AQ1000 THERMOSTATS
IMPORTANT
The AQ25A is not an Outdoor Reset Boiler Control
Panel. The purpose of the outdoor sensor is to
communicate the outdoor temperature to the
AQUATROL network for display on all AQ1000
thermostats.
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 for typical placement. Outdoor sensor comes with
10 ft. (3 m) 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.
AQ25A SERIES PROGRAMMABLE BOILER CONTROL PANELS
IMPORTANT
M13763
System Demands Wiring
Additional information about settings for the various System
Demands is discussed in Table 6 on page 30.
AUX-IN
If the optional Aux In. contacts (terminals 9 and 10) will be
used, wire them now. These inputs are powered with 24 Vdc
and must connect only to a dry closure contact (unpowered
switch).
The Aux-In contact closure sets the system into a specific state
as determined by the installer setup using the EQUIPMENT
SETUP > AUXILIARY I/O sub-menu (see Fig. 25 on page 38).
HEAT DEMAND
If the optional Heat Demand (terminals 11 and 12) will be used,
wire them to a system setpoint demand (dry contact closure),
such as a pool or spa Aquastat®.
The HEAT contact closure drives the system to control either at
the Reset temperature or the Setpoint temperature as
determined by the installer setup using the EQUIPMENT
SETUP > ZONING > HEAT DMND selection (see Fig. 25 on
page 38). Heat Demand priority allows only heat for the first 30
7
Fig. 7. Outdoor temperature sensor installation.
Do not run sensor wires parallel, or close, to
telephone, Ethernet, or power cables. Cross all
power, Ethernet, and telephone wiring at right angles.
If sensor wires are located in an area with strong
sources of electromagnetic interference, or EMI, (e.g.,
if sensor wires are run in the same electrical chase as
line voltage wiring) use twisted pair, shielded cable, or
run wires in a grounded metal conduit. This is
important, since the calculated temperature - based
on the sensor's resistance reading - can be distorted
by high EMI, potentially causing the AQ25A to not
operate properly. If using shielded cable or conduit,
connect the shield wire to earth ground only at the
AQ25A panel. do not ground the shield or conduit at
any other location or electromagnetic shielding will be
ineffective. If shielded cable is used, Honeywell
recommends the use of shielded cable with a
continuous ground plane, such as foil, with an integral
drain wire for bonding to earth ground.
M13775
69-2119—02