Monitoring a Solar Pump System12.6
Monitoring the pump Will you be able to observe the
output of your pump at the point of discharge? If not,
you may not know if it malfunctions. Consider installing a
water meter, or additional valves so that the flow can be
directly observed. See illustration in section 13.4
Monitoring the water level in your storage tank
Will you be able to observe the level of water in your tank?
If you cannot easily see into your storage tank, here are
some methods of tank monitoring.
dipstick in the air vent1.
float with a visible rod that protrudes through the 2.
top of the tank
clear sight-tube alongside the tank3.
precision pressure gauge (note: 1 PSI = 2.3 ft)4.
Freeze Protection for Solar Water Pumps12.7
In a cold climate, water can freeze in a pipe and block the
water flow. This will cause an electrical overload that will
cause the pump to stop.
Pressure relief If there is any possibility of a pipe freez-
ing, install a pressure relief valve to prevent excess pressure
in the pump line. Install it below frost line. Adjust the valve
to open if the pressure exceeds normal. This is especially
important for helical rotor pumps (model number not
containing “C”) which can develop very high pressure.
Burial of pipe The best way to prevent freezing is to bury
all piping below frost line. The modern method of burial at
the wellhead is to install a pitless adapter. See section 13.4,
Wellhead Assemblies for Drilled Wells
Weep hole If you have above-ground piping that must
be drained for freeze protection, make a tiny “weep hole”
in the drop pipe, below frost line. This will cause a constant
(but very small) leakage of water back into the well. When
the pump stops, the pipe will drain back slowly. The pipe
must be sloped without low spots, so it drains completely.
In plastic pipe, a weep hole can be made with a hot needle
or an extremely small drill bit, or a needle valve can be
installed and adjusted.
Weep hole – “high tech” version The most reliable
way to control dripping is to use a “drip emitter” made for
drip irrigation systems. It will resist accumulation of debris
and mineral deposits far better than a simple hole or a
needle valve. Emitters are available from irrigation suppli-
ers, nurseries, and many hardware stores. They are rated
in gallons (liters) per hour. The most common ones are in
the range of 1 – 2 US gal. (4 – 8 l) per hour. Use a relatively
fast one for best reliability, especially if you get mineral
deposits. Drill a hole in the pipe to fit the emitter, and push
the emitter into the hole.
Drip emitters are made for a pressure limit of about 40 PSI
(2.8 bar). This limits the vertical lift above the emitter
to about 90 ft (28 m). In cases of relatively high lift, use
a “pressure compensated” emitter. It will maintain a
relatively constant drip rate as the pressure varies. This will
reduce water loss when the pump is running.
Polyethylene pipe Flexible “poly pipe” (PE) has proven
to tolerate repeated freezing. Connections may loosen from
ice expansion, but the pipe is not damaged. Poly pipe is
often used in places where pipe may freeze accidentally or
occasionally. See section 7.3 for precautions regarding PE
pipe. If you plan to bury PE pipe, observe further precau-
tions supplied by the pipe manufacturer.
WARNING Do not install the pump
with its check valve removed.
QUESTION Will the pump
drain back when it stops? —
ANSWER NO! The pump has a
check valve that stops water from draining
back down when it stops. A helical rotor pump
will not drain back even if the check valve is
removed.
To Next Page
Loading...
Need help?
General
