![background image](http://html.mh-extra.com/html/carrier/aquazone-50hql072-120/aquazone-50hql072-120_installation-start-up-and-service-instructions-manual_2563393031.webp)
31
heat/cool mode, Y1 is used for cooling stage 1, Y2 is used for
cooling stage 2, W1 is used for heating stage 1 and O/W2 is
used for heating stage 2. Select ON for heat pump applications.
In heat pump mode, Y1 used is for compressor stage 1, Y2 is
used for compressor stage 2, W1 is used for heating stage 3 or
emergency heat, and O/W2 is used for RV (heating or cooling)
depending upon switch 4 setting.
O/B Thermostat Type — Switch 4 provides selection for heat
pump O/B thermostats. O is cooling output. B is heating out-
put. Select ON for heat pumps with O output. Select OFF for
heat pumps with B output.
Dehumidification Fan Mode — Switch 5 provides selection
of normal or dehumidification fan mode. Select OFF for dehu-
midification mode. The fan speed relay will remain OFF dur-
ing cooling stage 2. Select ON for normal mode. The fan speed
relay will turn on during cooling stage 2 in normal mode.
Switch 6 — Not used.
Boilerless Operation — Switch 7 provides selection of boiler-
less operation and works in conjunction with switch 8. In
boilerless operation mode, only the compressor is used for
heating when FP1 is above the boilerless changeover tempera-
ture set by switch 8 below. Select ON for normal operation or
select OFF for boilerless operation.
Boilerless Changeover Temperature — Switch 8 on S1 pro-
vides selection of boilerless changeover temperature set point.
Select OFF for set point of 50 F or select ON for set point
of 40 F.
If switch 8 is set for 50 F, then the compressor will be used
for heating as long as the FP1 is above 50 F. The compressor
will not be used for heating when the FP1 is below 50 F and the
compressor will operate in emergency heat mode, staging on
EH1 and EH2 to provide heat. If a thermal switch is being used
instead of the FP1 thermistor, only the compressor will be used
for heating mode when the FP1 terminals are closed. If the FP1
terminals are open, the compressor is not used and the control
goes into emergency heat mode.
DIP SWITCH BLOCK 2 (S2) — This set of DIP switches is
used to configure accessory relay options. See Fig. 8B, 9B and
10B.
Switches 1 to 3 — These DIP switches provide selection of
Accessory 1 relay options. See Table 17 for DIP switch
combinations.
Switches 4 to 6 — These DIP switches provide selection
of Accessory 2 relay options. See Table 18 for DIP switch
combinations.
Auto Dehumidification Mode or High Fan Mode — Switch 7
provides selection of auto dehumidification fan mode or high
fan mode. In auto dehumidification fan mode the fan speed
relay will remain off during cooling stage 2 if terminal H is
active. In high fan mode, the fan enable and fan speed relays
will turn on when terminal H is active. Set the switch to ON for
auto dehumidification fan mode or to OFF for high fan mode.
Switch 8 — Not used.
Table 17 — DIP Switch Block S2 —
Accessory 1 Relay Options
LEGEND
NOTE: All other DIP switch combinations are invalid.
Table 18 — DIP Switch Block S2 —
Accessory 2 Relay Options
LEGEND
NOTE: All other switch combinations are invalid.
Units with Modulating Hot Water Reheat
(HWR) Option —
A heat pump equipped with Hot Water
Reheat (HWR) can operate in three modes: cooling, cooling
with reheat, and heating. The cooling/heating modes are like
any other Aquazone™ water source heat pump. The reversing
valve ("O" signal) is energized in cooling, along with the com-
pressor contactor(s) and blower relay. In the heating mode, the
reversing valve is deenergized. Almost any thermostat will
activate the heat pump in heating or cooling modes. The
Deluxe D microprocessor board, which is standard with the
HWR option, will accept either heat pump (Y,O) thermostats
or non-heat pump (Y,W) thermostats.
The reheat mode requires either a separate humidistat/
dehumidistat or a thermostat that has an integrated dehumidifi-
cation function for activation. The Deluxe D board is config-
ured to work with either a humidistat or dehumidistat input to
terminal “H” (DIP switch settings for the Deluxe D board are
shown in Table 19). Upon receiving an “H” input, the Deluxe
D board will activate the cooling mode and engage reheat.
Table 19 — Humidistat/Dehumidistat Logic and
Deluxe D DIP Switch Settings
Table 20 shows the relationship between thermostat input
signals and unit operation. There are four operational inputs for
single-stage units and six operational inputs for dual-stage
units:
• Fan Only
• Cooling Stage 1
• Cooling Stage 2
• Heating Stage 1
• Heating Stage 2
• Reheat Mode
HWR APPLICATION CONSIDERATIONS — Unlike
most hot gas reheat options, the HWR option will operate over
a wide range of entering-water temperatures (EWTs). Special
flow regulation (water regulating valve) is not required for low
EWT conditions. However, below 55 F, supply-air tempera-
tures cannot be maintained at 72 F because the cooling capacity
exceeds the reheat coil capacity at low water temperatures. Be-
low 55 F, essentially all water is diverted to the reheat coil (no
heat of rejection to the building loop). Although the HWR op-
tion will work fine with low EWTs, overcooling of the space
may result with well water systems or, on rare occasions, with
ground loop (geothermal) systems (NOTE: Extended range
units are required for well water and ground loop systems).
Since dehumidification is generally only required in cooling,
most ground loop systems will not experience overcooling of
the supply-air temperature. If overcooling of the space is a con-
cern (e.g., computer room well water application), auxiliary
heating may be required to maintain space temperature when
ACCESSORY 1
RELAY OPTIONS
DIP SWITCH POSITION
1
2
3
Cycle with Fan
On
On
On
Digital NSB
Off
On
On
Water Valve — Slow Opening
On
Off
On
OAD
On
On
Off
NSB —
Night Setback
OAD —
Outside Air Damper
ACCESSORY 2
RELAY OPTIONS
DIP SWITCH POSITION
4
5
6
Cycle with Fan
On
On
On
Digital NSB
Off
On
On
Water Valve — Slow Opening
On
Off
On
OAD
On
On
Off
NSB —
Night Setback
OAD —
Outside Air Damper
Sensor
2.1
2.2
2.3
Logic
Reheat
(ON) - H
Reheat
(OFF) - H
Humidistat
Off
Off
Off
Reverse
0 VAC
24 VAC
Dehumidistat
Off
On
Off
Standard
24 VAC
0 VAC