Nordic R-45, Installation And Service Manual, Page: 31 / 91

1-Nov-2021 Page 31 001200MAN-09
A return well should be a minimum of 80 ft. from the supply
well for residential applications. The water returned to the well
will not necessarily be pumped into the same aquifer, depend-
ing on underground conditions. The return well must be able to
supply at least the same quantity of water as the amount you
wish to inject into it, preferably much more, since injection ca-
pacity will tend to decrease over time due to clogging. It may be
necessary to place a pressure-tight cap on the well to keep the
return water from flowing out the top of the well. This cap is
commonly required since a certain amount of pressure may be
needed to force the return water back down the well in cases of
limited injectivity.
Water discharged by percolation will generally soak into
the ground within a distance of 50 to 100 ft. If suitable care is
taken to ensure that the drain pipe runs downhill and the end of
the pipe is protected by a bale of hay or spruce bows, the end of
the pipe will not freeze as the pipe will empty out when the heat
pump shuts off and the water valve closes. A screen should be
installed on the end of large discharge pipes, to prevent animals
from building nests inside during extended ’off’ periods and
causing a backflooding risk for open water drains.
When snow comes it will usually cover the entire process
much like a small spring. It is recommended that the pipe be
below the frost line when possible for maximum freeze protec-
tion.
When discharging into a river or stream, or above the sur-
face of a pond, the same guidelines should be followed as de-
scribed in the paragraph above for the percolation method.
When discharging the waste water below the surface of a
pond or lake, the discharge pipe should be placed below the
frost line to prevent the pipe from freezing. As opposed to the
percolation method, water will remain in the end of the pipe. It
is recommended that the surface of the pond be lower than the
installation location of the heat pump. This reduces the back
pressure generated by the weight of the water in the pond.
Water Valve
Water flow through the heat pump is turned on and off by a
water valve, which is controlled by a 24VAC signal from the
heat pump. It should be installed on the OUT pipe of the heat
pump, so that the heat exchanger remains full of water at all
times. There are two types of water valves available from Mari-
time Geothermal.
Most installations use a ‘Taco’ slow closing motorized ball
valve (EBV). This takes ~5 seconds to close, and avoids the
water hammer which can occur with faster acting valves. There
is also a more economical fasting acting ‘Rainbird’ solenoid
valve available, for applications where water hammer is not
expected. Both come with a wiring harness, which plugs into a
connector behind the pipe post of the heat pump. This both
allows the heat pump to properly control the valve, turning the
water flow on and off with the compressor, and also tells the
heat pump to select the higher low pressure safety control for
open loop operation (since there is no antifreeze present).
Water Flow Control
A flow restricting (‘Dole’) valve is highly recommended,
installed downstream of the water valve. This is a passive (non-
electrical) device which automatically varies the size of its rub-
ber orifice in order to restrict flow to its stamped gpm value, re-
gardless 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
Figure 2: Open Loop Accessories & Tools
Gauge adapter
for P/T port
P/T port
P/T adapters for
heat pump
(1” NPT to barb)
Taco EBV
Rainbird Solenoid Valve
Dole Valve
Water
Level
Sounder
Cumulative
Gallon
Meter