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replacement indirect solar water heater tank?

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Posted by N8N on April 21, 2009, 4:28 pm
Hi all,

My house has a solar water heater installed by the previous owners.
The tank is dying (leaking on my laundry room floor) so I will be
bypassing it as soon as I have a free evening.  Question is, I've been
doing some looking around online, I can't seem to find a replacement
tank that would make it worth my while to keep the system installed.
Ones I've found are >$K and I just don't think that it's saving me
that much on my gas bills.  I have a very shady lot and I haven't ever
seen the output temp of the solar tank over 90F.  Can someone tell me
where is the best deal on a replacement tank?  also, how to refill the
loop between the tank coil and the collector?  it's a pressurized
system with antifreeze, running at about 20 PSI.  Also, is there a
good deal out there on a controller with thermocouples?  PO's had the
pump just running on a time switch which I think is probably part of
the problem, on an overcast winter day it might actually be shedding
heat to the outside rather than heating the water.



Posted by gary on April 23, 2009, 1:44 am

The solar tanks with internal heat exchangers tend to be expensive.
You might go with a regular electric hot water tank as the storage
tank, and use an external heat exchanger.
Or, change over to the Butler type system that uses the existing hot
water tank for both storage and back up heating (search for "Butler"
on this page: http://www.builditsolar.com/Projects/WaterHeating/water_heati=

For instructions on refilling the system, go to the same page as is
listed above, and see the Home Power article on closed loop systems
-- "Solar Hot Water for Cold Climates,  Parts I and II, Ken Olsen and
Tom Lane"
Gives a very detailed, hands on description of closed loop systems --
including how to install.

Two common differential controllers are the Goldline GL-30, and Steca
306(?).  I use both, and (I think) they are both good.  The Steca has
a nice little LED screen that tells you whats going and and gives tank
and collector temps.
Both are in the $50 area with sensors (which are thermistors).  Lots
of places carry them -- e.g. King Solar, ebay, ...  You definitely
want a differential controller -- its just not possible to do this
Big list of suppliers here:  http://www.builditsolar.com/References/supplie=

A few tanks listed here:

If you wanted to tackle a fairly large project, you could convert your
system to one like this:
Not saying this is a good way for you to go, but just one more option.


Posted by N8N on April 23, 2009, 1:01 pm
 On Apr 22, 9:44pm, g...@builditsolar.com wrote:

Thank you for the reply.  I'll have to check out your links when I get
home.  hopefully that will get me pointed in the right direction.  I
do have a conventional 40-gal gas fired tank so I can just bypass the
solar tank for now until I figure out exactly what I'm doing.  (should
have done that already, but been busy this week - right now there's
old towels on the laundry room floor.  A rather inelegant solution...)


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