Manual 2100-583G
Page
22 of 48
THIN ICE MAY RESULT IN THE VICINITY
OF THE DISCHARGE LINE.
LAKE AND POND INSTALLATIONS
Lakes and ponds can provide a low cost source of water
for heating and cooling with a ground water heat pump.
Direct usage of the water without some filtration is not
recommended as algae and turbid water can foul the water
to refrigerant heat exchanger. Instead, there have been
very good results use a dry well dug next to the water line
or edge. Normal procedure in installing a dry well is to
backhoe a 15 to 20 foot hole adjacent to the body of water
(set backhoe as close to water’s edge as possible). Once
excavated, a perforated plastic casing should be installed
with gravel backfill placed around the casing. The gravel
bed should provide adequate filtration of the water to
allow good performance of the ground water heat pump.
The following is a list of recommendations to follow when
installing this type of system:
A. A lake or pond should be at least 1 acre (40,000
square feet) in surface area for each 50,000 BTUs
of ground water heat pump capacity or have 2 times
the cubic feet size of the dwelling that you are
trying to heat (includes basement if heated).
B. The average water depth should be at least 4 feet
and there should be an area where the water depth
is at least 12 to 15 feet deep.
C. If possible, use a submersible pump suspended in
the dry well casing. Jet pumps and other types of
suction pumps normally consume more electrical
energy than similarly sized submersible pumps.
Pipe the unit the same as a water well system.
D. Size the pump to provide necessary GPM for the
ground water heat pump. A 12 GPM or greater
water flow rate is required on all models when used
on this type system.
E. A pressure tank should be installed in dwelling to
be heated adjacent to the the ground water heat
pump. A pressure switch should be installed at the
tank for pump control.
F. All plumbing should be carefully sized to
compensate for friction losses, etc., particularly if
the pond or lake is over 200 feet from the dwelling
to be heated or cooled.
G. Keep all water lines below low water level and
below the frost line.
H. Most installers use 4-inch field tile (rigid plastic or
corrugated) for water return to the lake or pond.
I. The drain line discharge should be located at least
100 feet from the dry well location.
J. The drain line should be installed with a slope of
2 inches per 10 feet of run to provide complete
drainage of the line when the ground water heat
pump is not operating. This gradient should also
help prevent freezing of the discharge where the
pipe terminates above the frost line.
K. Locate the discharge high enough above high water
level so the water will not back up and freeze inside
the drain pipe.
L. Where the local conditions prevent the use of a
gravity drainage system to a lake or pond, instead
run standard plastic piping out into the pond below
the frost and low water level.
For complete information on water well systems and lake
and pond applications, refer to Manual 2100-078 available
through your distributor.
GROUND WATER (WELL SYSTEM APPLICATIONS)
