Using Recycled Bulk Milk Tanks for
Solar Heat Storage Tanks
Tom Snyder has suggested another
good option for solar heat storage tanks. He uses used stainless steel
bulk milk tanks.
These tanks are available for about $1 per gallon used. Sizes range
from about 300 to 500 gallons. They are probably easiest to find in
areas with a lot of dairy farming activity.
Tom's company is Alternate
Energy Systems -- their www.sunnystuff.net website
has a lot of interesting content.
Thanks very much to Tom for sending this in!
These are some pictures and description from Tom of one of his installations:
The
beginning of installing a 340 gallon Stainless Steel Tank for preheat of
DHW and in floor radiant heat using 6 - 3X8 solar panels.
The plumbing for the solar pump, temperature
and pressure gauges.
A closeup of the 3/4 inch copper coil for
the solar loop (bottom)
and two 3/4 inch 60 foot copper coils in parallel for the DHW preheat.
The plumbing for the solar pump, temperature and
pressure gauges
A closeup of the old style aquastat and
temperature gauge for the in floor heat system.
The solar "manifold" for the solar loop from the collectors to the coils
in the tank or outboard plate type exchanger. This solar manifold
consists of a cast iron pump, 2 fill valves, swing check valve, in line
ball valve to help with filling the system, Schrader valve, relief valve
and a P/T gauge.
The tanks include insulation on the sides
and bottom. I never have cut into the sides, but it is very effective for
keeping milk cold and water hot. In an article for Home Power I was flippant
when I told one customer to "turn the tank over to put the insulation on top".
On the top I usually put at least 2 inches of rigid foam and sometimes a
fiberglass batt. On two projects, an insulated room in the basement was built
around the tank, and on one we had the tank in an insulated box in an unheated
attached garage with openings into the basement for heat into the box. I also
saw this method used on new homes in Omaha a
few years ago.
On the photos of the tank, the wires to the sensors can be seen at the front,
top. A minor word of caution in using this method (a 1/2 inch of capped
copper). Over time the tube will get some moisture in it from
condensation which could finally ruin the sensor. Two ways to solve this is to
silicon the top of the tube and the second is to make sure the sensor is not
clear to the bottom of the tube.
Tom Snyder
Alternate Energy Systems
NABCEP ST certificate
Northeast Iowa Community College
Solar Thermal Licensing Instructor www.sunnystuff.net
Tom wrote an article for Home Power titled "Solar Heating Basics Part
Two — Storage of Solar Energy", that has some additional material on using bulk
milk tanks for heat storage and other cost effective heat storage methods.
The article appears in Home Power issue 42, August/September 1994.
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