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13.3 Wellhead Assemblies for Drilled Wells
To support the drop pipe and seal the
wellhead, choose one of these methods:
Well Seal System
These methods are NOT specific to solar
pumps. The components are available from
conventional water well suppliers.
The well seal is a plate that fits on top of the
well casing. It provides a seal against
contamination, and it supports the weight of
the in-well assembly. In a freezing climate, the
wellhead must be located in a heated building
or in a covered well pit, or the pipe must be
made to drain when the pump stops (see
Section 13.6 Freeze Protection).
Use metal pipes above ground, for strength.
A tee and a plug is used instead of an elbow,
because the plug allows direct observation of
water level and flow. It also provides a place
to attach a lifting device.
Pitless Adapter System
The pitless adapter is a fitting that allows your
buried pipe to pass through the well casing
underground, without the need to build a
covered pit. It provides protection against
freezing, flooding, animals and human
activities that can damage exposed piping.
After the pitless adapter is installed, the pump
can be installed and removed from above,
with no further need to dig. The inside half
slides apart vertically by means of a dovetail
joint and an O-ring. A piece of threaded pipe
is used as a temporary tool for installation or
removal. Thread it into the socket on the
inside half of the adapter.
If the well casing is 4" (inside diameter) the
pitless adapter must be designed not to
reduce the clearance inside the casing (it
clamps around the outside of the casing).
Two pumps in one well
If you have a well
casing of 6" or larger, you may be able to
install two pumps in the well, by using two
pitless adapters.
Check Valve
A check valve (non-return valve) prevents
stored water from escaping down the well in
case of a leak in your drop pipe. It may also
help the pump to start easier if it feeds into a
very long pipeline. If you use a weep hole for
freeze protection, omit this check valve to
allow the pipe to drain.
plug
check valve
eye bolt
safety
rope
metal
pipe
section
well
seal
well
chasing
electric cable
electrical
conduit
well
chasing
well cap
electric cable
temporary puller
pipe
eye bolt
check valve
optional
pitless
adapter
drop pipe