Nordic R-09, Инструкция по установке и обслуживанию

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11-May-2021 Page 25 002512MAN-01
Water Flow Control
A flow restricting (‘Dole’ or ‘Hays’) valve is highly recom-
mended, installed downstream of the water valve. This is a
passive (non-electrical) device which automatically varies the
size of its rubber orifice in order to restrict flow to its stamped
gpm value, regardless of water pressure. This is important in
order to provide some backpressure to the water system, which
could otherwise be too low for the comfort of people taking
showers or otherwise using the domestic water system. It also
prevents excessively low refrigerant discharge pressure when in
cooling mode. Dole valves are available as an accessory.
Dole valves can emit a ‘whistling’ sound if the pressure
drop through them is high. Therefore, they should be placed
where the noise will not cause a nuisance, e.g. outside the
basement wall or perhaps in a well insulated box. Hays flow
restrictors do not have this drawback.
Submersible Pump Selection
Of course, the submersible pump must be large enough to
supply the flow required by the heat pump. This is usually not a
problem, pumps often being oversized by default.
However, if a conventional fixed speed pump is too large,
its fixed capacity will exceed that of the Dole valve at reasona-
ble pressure switch settings (<80 psi). This will cause the sub-
mersible pump to cycle on and off continuously while the heat
pump is running, causing excessive wear to the submersible
pump. The installation of a large air bladder tank will cause the
cycles to have a longer duration, but will not solve the problem.
To avoid this problem, the fixed speed pump should be
sized according to its head vs. flow curve. The required head
should be calculated using height between the pumping fluid
level in the well and the elevation of the heat pump, pipe pres-
sure drop at nominal flow rate, desired system water pressure,
and any back pressure from return well. Then a pump can be
selected that delivers the nominal flow for the chosen heat
pump size at that head. In case this calculation is not exact, a
variety of Dole valves can be carried by the installer, and a larg-
er Dole valve installed if submersible pump cycling is observed.
An alternate approach would be to install a variable speed
submersible pump, which varies its speed to maintain a con-
stant water system pressure. Or use a mechanical ‘cycle stop’
valve, which is installed upstream of the air bladder / pressure
tank and varies its orifice to put backpressure on the pump dur-
ing periods of low flow in order to keep it from cycling off.
Plumbing the Heat Pump
The port connections for the Outdoor Loop are 1/2” or
3/4” brass FPT fittings. They are marked as OUTDOOR IN
and OUT.
Plumbing lines, both IN (supply) and OUT (discharge), must
be of adequate size to handle the water flow necessary for the
heat pump. A copper or plastic line should be run to the Out-
door IN pipe of the heat pump. Similarly, a line should be run
from the Outdoor OUT pipe to the method of disposal. P/T
plugs should be installed at each port. See diagram in the
Ground Loop chapter for a description of P/T plugs. The water
valve should be installed in the OUT (discharge) line. Refer to
drawing 000907CDG at the end of this section for the recom-
mended setup. Placing the water valve in the discharge line
ensures that the heat exchanger inside the heat pump remains
full of water when the unit is not running. Unions or some other
form of disconnect should be used so that the coaxial heat ex-
changer may be accessed should it required cleaning.
The heat pump has an electrical connector for the water
valve just inside the case. After the water valve is installed, run
the valve harness into the case through the hole provided. Re-
move the jumper plug from the Valve Connector and connect
the harness in its place.
Optionally, a water flow meter can be installed in the dis-
charge line so that the exact amount of water flowing can be
determined at a glance. It should be placed between the Out-
door OUT (Supply OUT) pipe of the heat pump and the water
valve.
With proper flow, there should be 5-7°F (3-4°C) delta T
between the IN and OUT water temperatures of the heat pump
when operating in the heating mode.
All water line valves on both the supply and discharge lines
should be either BALL or GATE valves. GLOBE valves have a
higher pressure drop, meaning more pumping power to maintain
the required flow to the heat pump.
Pipe Insulation
All ground water piping to and from the Outdoor Loop ports
on the heat pump should be insulated with 3/8” closed cell pipe
insulation, to prevent condensation and dripping onto floors or
walls.