9
NSKW INSTALLATION MANUAL
to determine the flow rate. These ports should be located
adjacent to the supply and return connections on the unit.
The proper flow rate cannot be accurately set without
measuring the water pressure drop through the refrigerant-
to-water heat exchanger (See Pressure Drop Table for water
flow and pressure drop information). Normally about 0.054
L/s per kW flow rate of cooling capacity (0.040 L/s per kW
minimum) is needed. Both source as well as load fluid piping
must be at least as large as the unit connections on the heat
pump (larger on long runs).
Never use flexible hoses of a smaller inside diameter than that
of the water connection on the unit and limit hose length to
3.05 m per connection. Check carefully for water leaks.
CAUTION: Water piping exposed to outside
temperature may be subject to freezing.
Open Loop Well Water Systems
Always maintain water pressure in the heat exchanger by
placing water control valves at the outlet of the unit. Use
a closed bladder type expansion tank to minimize mineral
deposits. Ensure proper water flow through the unit by
checking pressure drop across the heat exchanger and
comparing it to the figures in the pressure drop table.
Normally, about 0.038 L/s per kW flow rate of cooling
capacity is needed in open loop systems, 0.029 L/s per kW
minimum if entering source temperature is above 10°C.
Some water control valves draw their power directly from
the unit’s 24V transformer and can overload and possibly
burn out the transformer. Check total VA draw of the water
valve(s) and ensure it is under 40 VA.
Discharge water from a heat pump can be disposed of in
various ways depending on local building codes (i.e. recharge
General
Each unit is equipped with captive female pipe thread (FPT)
water connections to eliminate ‘egg-shaping’ from use of
a backup wrench. For making the water connections to
the unit, a Teflon tape thread sealant is recommended to
minimize internal fouling of the piping. Do not over tighten
connections. All supply and return water piping should be
insulated to prevent excess condensation from forming on
the water lines.
NOTES: 1) WaterFurnace recommends a male national pipe
thread (NPT) to British standard pipe fitting (BSPF) to
adapt to NSKW water connections. 2) Units are factory run-
tested using propylene glycol. Prior to connecting piping
to unit, thoroughly flush heat exchangers.
The piping installation should provide service personnel with
the ability to measure water temperatures and pressures.
The water lines should be routed so as not to interfere with
access to the unit. The use of a short length of high pressure
hose with a swivel type fitting may simplify the connections
and prevent vibration. Optional stainless steel hose kits are
available as an accessory item.
Before final connection to the unit, the supply and return
hose kits must be connected, and the system flushed
to remove dirt, piping chips and other foreign material.
Normally, a combination balancing and close-off (ball) valve
is installed at the return, and a rated gate or ball valve is
installed at the supply. The return valve can be adjusted to
obtain the proper water flow. The valves allow the unit to be
removed for servicing.
The proper water flow must be delivered to each unit
whenever the unit heats or cools. To assure proper flow,
the use of pressure/temperature ports is recommended
Field Connected Water Piping
Line Voltage
Disconnect
Load Liquid
Connections
Water Out
Water In
Rubber Bladder
Expansion Tank
Solenoid
Valve
Flow Regulator Valve
Shut-off Valve
(to isolate solenoid
valve while acid
flushing)
Boiler Drains for
HX Flushing
Shut-off
Valve
Vibration Absorbing
Mesh or Air Pad
P/T Plugs
NOTE:
Valves and boiler drains must be installed
so the heat exchanger can be acid flushed.
Typical Open Loop Installation
