Heat Controller HTV Series - Electrical - Low Voltage Wiring; WATER SOLENOID VALVES

Heat Controller, Inc. HTV/HTD/HTH SERIES
26
Electrical - Low Voltage Wiring
23
ELECTRICAL - LOW VOLTAGE WIRING
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 11 or
the specific unit wiring diagram for details.
COMPONENT VA
Typical Blower Relay 6-7
Typical Reversing Valve Solenoid 4-6
30A Compressor Contactor 6-9
SubTotal 16-22
+CXM Board (5-9 VA)* 21-31
Remaining VA for Accessories 19-29
Low Voltage VA Ratings
* Standard transformer is 75VA.
Figure 11: Acce ssory Wiring
WATER SOLENOID VALVES
An external solenoid valve(s) should be
used on ground water installations to shut
off flow to the unit when the compressor is
not operating. A slow closing valve may be
required to help reduce water hammer.
Figure 11 shows typical wiring for a 24VAC
external solenoid valve. Figures 12 and 13
illustrate typical slow closing water control
valve wiring for Taco 500 Series and Taco
ESP Series valves. Slow closing valves
take approximately 60 seconds to open
(very little water will flow 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
Two-stage units should be designed with
two parallel valves for ground water
applications to limit water use during first
stage operation. For example, at 1.5
gpm/ton, a HTV048 unit requires 6 gpm for
full load (2
nd
stage) operation, but only 4
gpm during 1
st
stage operation. Since the
unit will operate on first stage 80-90% of the
time, significant water savings can be
realized by using two parallel solenoid
valves with two flow regulators. In the
example above, stage one solenoid would
be installed with a 4 gpm flow regulator on
the outlet, while stage two would utilize a 2
gpm flow 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 flow
rate.
Figure 11: Accessory Wiring