Lake And Pond Installations - Bard Q-TEC Series Literature Assembly

Pump

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-freon heat exchanger. Instead, there have
been very good results using 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 the 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 (Refer to Figure 35
on page 58):
A. A lake or pond should be at least 1 acre (40,000
a 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 a 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.
FIGURE 34
Cleaning Water Coil
Hose Bib (B)
Hose Bib (A)
Isolation Valve
TO WATER COIL
FROM WATER COIL
MIS-2750
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 modes when used
on this type system.
E. A pressure tank should be installed in dwelling to
be heated adjacent to 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, you can
instead run standard plastic piping out into the
pond below the frost and low water level.
Manual 2100-738A
Page 57 of 71