Comfort-Aire HWW120 - Manual (Page 10)

9
Installation & Operation WATER-TO-WATER (HWW) SERIES Heat Controller, Inc.
Water-Loop Heat Pump Applications
Commercial systems typically include a number of units
plumbed to a common piping system. Any unit plumbing
maintenance work can introduce air into the piping system,
therefore air elimination equipment is a major portion of the
mechanical room plumbing. In piping systems expected to
utilize water temperatures below 50°F [10°C], 1/2” [13mm]
closed cell insulation is required on all piping surfaces to
eliminate condensation. Metal to plastic threaded joints should
never be employed due to their tendency to leak over time.
Teflon tape thread sealant is recommended for FPT water
connections (commercial class) to minimize internal fouling
of the heat exchanger. Do not overtighten connections and
route piping so as not to interfere with service or maintenance
access. Hose kits are available from Heat Controller in
different configurations for connection between the system.
The piping system should be flushed to remove dirt, piping
chips, and other foreign material prior to operation. See
Piping System Cleaning and Flushing Procedures later in this
document. The flow rate is usually set between 2.25 gpm and
3 gpm per ton [2.9 l/m and 4.5 l/m per kW] of cooling capacity.
Heat Controller recommends 2.5 gpm per ton [3.2 l/m per
kW] for most applications of water loop heat pumps. To insure
proper maintenance and servicing, P/T ports are imperative
for temperature and flow verification, as well as performance
checks. See Figure 2 for typical water-loop application
installation.
Cooling Tower/Boiler Systems typically utilize a
common loop maintained 60-90°F [16-32°C]. The use of a
closed circuit evaporative cooling tower with a secondary
heat exchanger between the tower and the water loop
is recommended. If an open type cooling tower is used
continuously, chemical treatment and filtering will be
necessary.
Low Water Temperature Cutout Setting
CXM Control: When an antifreeze is selected, the FP1
jumper (JW3) should be clipped to select the low temperature
(Antifreeze 15°F [-9.4°C]) setpoint to avoid nuisance faults.
See Figure 5: Low Water Temperature Cutout - FP1.
� WARNING! �
� CAUTION! �
Never jumper terminal “A” from CXM board #1 to CXM
board #2 on multi-compressor/control bound units. See
Figure 6 [Page 15] in electrical section of this document
for motorized valve wiring.
CAUTION! Many units are installed with a factory or
field supplied manual or electric shut-off valve. DAMAGE
WILL OCCUR if shut-off valve is closed during unit
operation. A high pressure switch must be installed on
the heat pump side of any field provided shut-off valves
and connected to the heat pump controls in series with
the built-in refrigerant circuit high pressure switch to
disable compressor operation if water pressure exceeds
pressure switch setting. The field installed high pressure
switch shall have a cut-out pressure of 300 psig and a
cut-in pressure of 250 psig.
Air Pad or
Extruded
polystyrene
insulation board
Unit Power
Disconnect
Thermostat Wiring
Load Plumbing
Connection
Optional
Balancing
Valve
Water Out
Optional Low
Pressure Drop
Water Control
Valve
Ball Valve with
integral P/T plug
Stainless steel braid
hose with integral “J”
swivel
Y-Strainer
with blow-off
valve
Water In
Ball Valve with
integral P/T plug
Building
Loop
Figure 2: Typical Water-Loop Application