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Fig. 7. Outdoor temperature sensor installation.
IMPORTANT
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 because the calculated temperature
- based on the sensor's resistance reading - can be
distorted by high EMI, potentially causing the AQ252
to not operate properly.
If using shielded cable or conduit, connect the shield
wire to earth ground only at the AQ252 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.
System Demands Wiring
Additional information about settings for the various System
Demands is discussed in Table 6 on page 32.
AUX-IN
If the optional Aux In. contacts (terminals 11 and 12) 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 41).
HEAT DEMAND
If the optional Heat Demand (terminals 13 and 14) will be used,
wire them to a system setpoint demand (dry contact closure),
such as a pool or spa Aquastat®.
AQ252 Universal Injection/Mixing Boiler Reset Control Panels
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 41). Heat Demand priority allows only heat for the first 30
minutes of a call for heat and then allows the space heating
needs to be added in for the next 30 minutes. This cycle
continues until the call for heat is satisfied.
DOMESTIC HOT WATER
Wire the DHW (terminals 15 and16) to the Aquastat or
thermostat on the domestic hot water tank.
DHW priority allows only DHW heat for the first 30 minutes of a
call for DHW and then allows the space heating needs to be
added in for the next 30 minutes. This cycle continues until the
call for DHW is satisfied.
M13775
NOTE: If the AQ252 is connected to a modulating
Low Voltage Outputs Wiring
10 VDC
The 10 Vdc terminals (17 and 18) of the AQ252 produce a
modulating (0-10 Vdc or 2-10 Vdc) signal that can drive a
modulating boiler's combustion fan or a modulating mixing
device, such as a motorized mixing valve or a variable-speed
injection pump.
FLOATING ACTION OUTPUT
BOILER
Wire the Boiler dry contact output (terminals 22 and 23) to the
T-T terminals on the boiler Aquastat or the boiler's control
panel. See Fig. 15 on page 13 for wiring connections to a
typical boiler Aquastat.
These contacts are made any time the system has a request
for boiler operation, unless the water supply temperature is
above the target temp at that time. If this occurs, the system
primary boiler pump would come on.
9
condensing boiler with built-in DHW management, the
DHW tank's Aquastat should be connected to the
AQ252's DHW (terminals 15 and 16). The AQ252's
Aux. Out (terminals 24 and 25) should be wired to the
boiler's DHW input terminals to the AQ252.
Boiler Signal: If the AQ252 panel is configured to send a
0-10V or 2-10V signal to a modulating/condensing
boiler, connect the AQ252's modulating output terminals
(17 and 18) to the modulating signal input on the boiler
control.
Secondary Loop Control: If a 0-10V or 2-10V driven
variable speed injection pump or a modulating mixing
valve is used for controlling the temperature of the
secondary loop, wire the mixing device to the - and +
terminals (17 and 18) of the AQ252.
Floating action valve: If a floating action valve is used for
controlling the temperature of the secondary (mixed)
loop, wire the Common (Com), Open (O), and Close (C)
(terminals 19, 20, and 21) of the AQ252 to the
corresponding terminals on the mixing valve's actuator.
69-1986—02
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