Residential H&V - 60Hz R22 &R410A
Rev.: 22 Dec, 2008
22
Water-Source Heating and Cooling Systems
Electrical - Low Voltage Wiring
Figure 22: Accessory Wiring
Figure 23: AVM Valve Wiring
C
C
Thermostat
Y1
1
2
3
Y1
AVM
Taco Valve
Heater Switch
Figure 24: Taco SBV Valve Wiring
From Water Source
IN
OUT
NOTE: Shut-off valves, strainers and
other required components not shown.
Solenoid
Valve
Flow
Regulator
To Discharge
Stage 1
Stage 2
Figure 25: Two-Stage Piping
Accessory Connections
A terminal paralleling the compressor contactor coil has
been provided on the CXM control. Terminal “A” is designed
to control accessory devices, such as water valves. Note:
This terminal should be used only with 24 Volt signals
and not line voltage. Terminal “A” is energized with the
compressor contactor. See Figure 23 or the specifi c unit
wiring diagram for details.
Water Solenoid Valves
An external solenoid valve(s) should be used on ground
water installations to shut off fl ow to the unit when the
compressor is not operating. A slow closing valve may be
required to help reduce water hammer. Figure 23 shows
typical wiring for a 24VAC external solenoid valve. Figures
24 and 25 illustrate typical slow closing water control valve
wiring for Taco 500 series (ClimateMaster P/N AVM…)
and Taco ESP series valves. Slow closing valves take
approximately 60 seconds to open (very little water will fl ow
before 45 seconds). Once fully open, an end switch allows
the compressor to be energized. Only relay or triac based
electronic thermostats should be used with slow closing
valves. When wired as shown, the slow closing valve will
operate properly with the following notations:
1. The valve will remain open during a unit lockout.
2. The valve will draw approximately 25-35 VA through the
“Y” signal of the thermostat.
Note: This valve can overheat the anticipator of an
electromechanical thermostat. Therefore, only relay or
triac based thermostats should be used.
Two-stage Units
Tranquility
27™ (TT) two-stage units should be designed
with two parallel valves for ground water applications to limit
water use during fi rst stage operation. For example, at 1.5
gpm/ton [2.0 l/m per kW], a TT049 unit requires 6 gpm [23 l/
m] for full load (2nd stage) operation, but only 4 gpm [15 l/m]
during 1st stage operation. Since the unit will operate on fi rst
stage 80-90% of the time, signifi cant water savings can be
realized by using two parallel solenoid valves with two fl ow
regulators. In the example above, stage one solenoid would
be installed with a 4 gpm [15 l/m] fl ow regulator on the outlet,
while stage two would utilize a 2 gpm [8 l/m] fl ow regulator.
When stage one is operating, the second solenoid valve will
be closed. When stage two is operating, both valves will be
open, allowing full load fl ow rate.
Figure 26 illustrates piping for two-stage solenoid valves.
Review fi gures 23-25 for wiring of stage one valve. Stage
two valve should be wired between terminal “Y2” (ECM
board) and terminal “C.” NOTE: When EWT is below 50°F
[10°C], a minimum of 2 gpm per ton (2.6 l/m per kW) is
required.
Section 10 - Packaged IOM 22 4/24/09 3:16:51 PM
(44 pages)
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