# Solar batch heater w/ anti freeze?



## LadyHawk77 (Oct 11, 2011)

So I love my way so easy solar batch water heater. But in the Midwest we must drain it for winter. I hate using gas to heat water when it is sunny but 20 outside.
So I got to thinking about running anti-freeze in the tank and supply/return lines. Then using a heat exchanger tank to warm 200' of pex that will pre-heat my H20 headed into my house water heater. 
Any thoughts? Anyone ever done this?


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## Ky-Jeeper (Sep 5, 2010)

Solar Water Heating Projects and Plans


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## SolarGary (Sep 8, 2005)

Hi,
I've never heard from anyone who has done that.

Its seems feasible, but I don't know what the heat exchanger would look like? 

It might be about as easy to convert over to the $1K type of system: 
The $1000 Solar Water Heating System

An advantage of the $1K would be that you would not have the large night losses from the outside tank that you do on the batch system.

Another option would be to keep the batch heater as is but add movable insulation over the glazing -- kind of like this one: 
http://www.builditsolar.com/Projects/WaterHeating/MSBatch.pdf
There are also some insulated batch heater schemes in the Bainbridge book: 
The Integral Passive Solar Water Heater Book

The trick with the insulated ones is remembering to move the insulation twice a day. 
*If someone could work out a good, automatic, reliable way to move the glazing insulation, it would be a great plus for batch heaters (summer and winter). *

The batch heater (even without the moveable insulation) take a long time to freeze because they have a lot of mass and some insulation from the glazing -- the part that usually freezes is the plumbing. So, if you can protect the plumbing that's a big help.


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## Jim-mi (May 15, 2002)

Running the pex in a tank with potable water is very questionable . . . . . .
There should be a double walled heat exchanger used.

Should a leak develop, ingesting water with antifreeze in it is not a good idea.

Yes with a proper heat exchanger your idea will work.
But your still going to need proper temperature sensors to control the pump(s)


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## LadyHawk77 (Oct 11, 2011)

Thanks everyone.
If I did an anti-freeze system I would run two lines of pex in the storage tank. One for house water and one for batch water.

Gary- Love your site. Thanks for all the free info. It is very helpful to have a place to reference for projects.
I do not have room on our South wall for the $1k project. I also have no basement or crawl space near the area the tank is set. I run the water from the batch heater underground, using your pinkboard plan, about 50 feet to the garage.
I do use insulation on my batch heater in early Spring and late Fall. I was thinking I would just amp it up for winter use. I uncover it in the morning when I let the chickens out and cover it back up when I put them in.


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## LadyHawk77 (Oct 11, 2011)

Forgot to say that when I put the waterlines in the ground (wrapped in pinkboard), I added an extra set. Just in case we figure out how to add in another project. I would like at some point to do Gary's solar shed plan. That way my storage/heat transfer tank could be placed in the ground.


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## Ky-Jeeper (Sep 5, 2010)

Food Grade Propylene Glycol, 15 Gallons [15gpg] | DudaDiesel Biodiesel Supplies


I use something very similar to this in pharmaceutical prescription packaging. Can be costly, but lots safer.


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## SolarGary (Sep 8, 2005)

LadyHawk77 said:


> ...
> 
> I do use insulation on my batch heater in early Spring and late Fall. I was thinking I would just amp it up for winter use. I uncover it in the morning when I let the chickens out and cover it back up when I put them in.



A great way to remember 

Gary


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