13
Installation, Operation & Maintenance - HKV Series
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 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 Comfort-Aire/Century in different configurations
as shown in Figure 5 for connection between the HKV
Series and the piping system. The hose kits include shut
off valves, P/T plugs for performance measurement, high
pressure stainless steel braid hose, "Y" type strainer
with blowdown valve, and "J" type swivel connection.
Balancing valves to facilitate the balancing of the system,
and an external low pressure drop solenoid valve for
use in variable speed pumping systems, may also be
included in the hose kit. 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.
The flow rate is usually set between 2.25 and 3.5 gpm
per ton [2.9 l/m and 4.5 l/m per kW] of cooling capacity.
Comfort-Aire/Century 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.
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 or DXM22 Control:
When an antifreeze is selected, the LT1 jumper (JW3)
should be clipped to select the low temperature
(Antifreeze 13°F [-10.6°C]) setpoint to avoid nuisance
faults. See Low Water Temperature Cutout Selection.
NOTE THAT THE EXTENDED RANGE OPTION SHOULD
BE SELECTED WHEN LOOP CONDITIONS ARE
EXPECTED TO DROP BELOW 60°F [16°C].
Figure 5: Typical Water Loop Application
Thermostat
Wiring
Unit
Power
Water In
Ball Valve with
integral P/T plug
Return Air
Field Supplied
Disconnect Box
Water Out
Water
Control Valve
Ball Valve with
integral P/T plug
TO Drain, See Fig. 4
Supply
Air
Supply
Air