# Anyone experiment with the 'batch' type water heater?



## slim62 (Nov 28, 2007)

Has anyone out ther experimented with the 'BATCH' type water heater with any success? Its our next project after we install our second wall heater and we were wondering on the success rate? or if anyone had thier 2 cents worth they would like to add or any helpful sites they could recomend?or a preferd /productive design scheam / Im wanting to build and install two seperate designs . one on our home and one for Dads extra small trailer . He only has a 5 gal. ele. water heater so it shouldnt take alot.


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## webbie (Nov 29, 2007)

Because I live in a freezing climate (along with many other members), I have not used or installed these - BUT, if I lived somewhere else I would definitely consider either buying one or making one. This is the type of heater that you see on roof in Israel, the Caribbean and many other locales. 

This site is a great solar resource for starters:
http://www.builditsolar.com/


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## cbrodsky (Nov 29, 2007)

I just got back from a little over a week in the Bahamas staying on one of the more remote islands.  I was shocked to find that not a single house had solar HW, yet the island's electric was overloaded and apparently gets cut off regularly.  And certainly no PV arrays.

They did generally use cisterns for water which was good, but then the rental house we were in had a top-loading washer instead of a front-loader.

My guess is that they have not become sufficiently enlightened to eliminate their high import duties on energy conservation products - I was told they pay duty of something like 45% on all imports.  This would certainly discourage such choices, when in fact they could probably simply offer a subsidized HW installation program and eliminate altogether their power plant expansion plans.

In contrast, practically every ramshackle cottage in Barbados had a rooftop solar HW system.  One could argue the Bahamas are a little more hurricane prone than Barbados which may reduce people's interest in such investments, but neither are immune.  My guess is they have some misguided government policies.

-Colin


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## slim62 (Nov 30, 2007)

Webmaster said:
			
		

> Because I live in a freezing climate (along with many other members), I have not used or installed these - BUT, if I lived somewhere else I would definitely consider either buying one or making one. This is the type of heater that you see on roof in Israel, the Caribbean and many other locales.
> 
> This site is a great solar resource for starters:
> http://www.builditsolar.com/



THANKS!! Great site!


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## Sandor (Dec 9, 2007)

The batch water heater is on my must do list this year, and there are plenty of free designs on the web.

I procured a used 40 gallon electric water heater that will be the tank, and I will build the frame and plumb it myself. A used sliding glass door will be the lid. Total investment... about a hundred bucks. Most for insulation and copper. Since it will be totally out of sight, I don't care what it looks like. This will act as a preheater to the current electric water heater. I will also put a temp gauge on the outlet pipe so I can monitor the temp of the water coming out of the batch unit.

I will use it from April to November. Drain it and bypass it in the offseason.

As far as experimenting goes, that garden hose laying in the sun during the summer was all I needed. That first blast of water is HOT. Since I keep good records of KWH usage, I should be able to estimate the impact of the unit.

Along the same line, I am going to put in another small tank behind the woodstove since there is plenty of room. This will also be a preheater to the electric water heater and be used year round. In the summer, I figure a tank of 58 degree water (inlet temp from the well) sitting in the room can't hurt either. The water will run through this first, before it heads to the batch solar heater.

I enjoy doing this kind of work.


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## ethcad (Dec 16, 2007)

One place recently that I saw a ton of these is China.  Incredible amount of construction going on and every house seemed to have one - even run down farmhouses.


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## Burn-1 (Dec 16, 2007)

Slim I think Nofossil who'll you'll see mostly on the Boiler Room Forum started his solar hot water system out with a batch heater. You might do a search for his posts.


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## pdboilermaker (Dec 17, 2007)

Slim 62:

You live in West Texas, close to Mexico by any chance?  These little beautys litter the roof tops of every house in Mexico and can be bought at any hardware store along the boarder.  Buy one from Mexico now before our dollar ='s a peso and maybe save a few bucks over building it yourself.


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## waverider (Dec 30, 2007)

Sandor said:
			
		

> Along the same line, I am going to put in another small tank behind the woodstove since there is plenty of room. This will also be a preheater to the electric water heater and be used year round.



Howdy, new member here.  Supplementing oil FHA wth wood stove in basement.  Only way to keep the first floor warm really is to fire up the basement stove.  Ground level basement walk out and adequate local supply makes wood heat practical/affordable.  Wondering about batch wood-preheating for electric hot water.  Anyone know of any references to proven, simply designs.   My rather unformed thoughts involve routing cold water supply through a collector plate - design TBD - (copper on steel? recycled  aluminum finned baseboard units?) installed between back of woodstove and masonry wall/chimney.  An auxiliary tank would be plumbed between collector plate and hot water tank.  Hoping to use just an electric h/w heater with element disconnected as auxiliary. Would the pressure relief valve on h/w tank used for storage enough to ensure safe operation?   What to do with stored hot water when system is not calling for more domestic hot water?   Just don't have the money to upgrade right now to a Toyotomi or some similar unit but hoping to reduce electric use and build a simple safe preheater. 
Comments are most welcome especially from those who have experimented with this concept.


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## Sandor (Dec 30, 2007)

Waverider,

You can build a collector loop behind the stove and circulate between the stove and storage with a pump, or the best approach would be thermo siphon.  That would work if you can locate your water storage above the stove.

The main point is that the water in the loop must constantly circulate for this setup to work.

The area behind my stove runs about 120-140, which is about right for hot water. The batch system is the easiest to implement, but can be the most unsightly. I want to use a short 20 gallon unit that I can hide behind the stove. If yours is in the basement, and your not concerned about looks, you can simply park an uninsulated (stripped of insulation) water heater next to the stove. Used water heaters are not to hard to find if you wanted to try it out, just put a temp gauge on the output side to see how effective it is.

Obviously, steam under pressure can be a dangerous thing. Monitor your setup closely while experimenting and employ pressure blow off valves where appropriate.


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## waverider (Dec 30, 2007)

Hey Sandor...
  Thanks for the thoughts.  The basement is my little bit of heaven.  Walk out at ground level to my wood yard, lots of head room, good access.  I have an old Tempwood, plate steel downdrafter (due for replacement but it  really cranks some heat with a full woodbox) connected to a 24'+ tall brick, interior chimney (once used for coal stoves) lined with 6" stainless.  Woodstove provides a layer of warm air at floor level of first floor, otherwise the winter temperature on the 1st floor below knee level in our healthily-drafty, partially-insulated, plaster wall farmhouse would never get above 50 degrees.
Regarding your design suggestion about a thermo-siphon placement above the collector position.  This would work because there is 7'6" clear to the bottom of the 6"x8" floor joists (110 year old home with hand-hewn timbers for the 1st floor deck and water-sawn balloon framed above).  This clearance means that placing a tank above stove would be possible and would also save floor space.   I was thinking apartment size tank (20 gallon) in line between collector and main tank.    
Please explain,  how does the collector tank thermo siphon back to the collector if there is also an outlet to domestic hot water?  Perhaps what you describe is a closed loop between collector and tank with heat exchanger to transfer heat to water supply. Also can an upright style water heater be used safely in a horizontal position?
To be honest I had some far fetched notion that I could put a thermostat controlled two way valve/pump arrangement and dump unused hot water to a zone of radiant and then mix the return back in to the cold water supply at the collector plate intake.   That sounds way ambitious but I am concerned about overheating etc... when domestic hot water use is at a minimum (say like 3 AM).   Don't really need a tank belching steamy waste heat out of pressure relief valves and wasting heat and water.
Questions, questions.  One of my surfing amigos is a seasoned boiler and radiant installer (though not a big wood burning fan) so I do have technical backup.  your thoughts and/or references to other threads or links would be most welcome.


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## Sandor (Dec 31, 2007)

Waverider,

Check out this site:. pdf warning. 

http://www.yukon-eagle.com/Portals/0/manuals/Hot%20Rod%20Manual%20(Revised).pdf

(for some odd reason, you need to cut and paste the url above into your browser for it to work)


This is actually a manual for the Hot Rod water heater system, but it works on the same concept as to what you are trying to do. They also strongly recommend that you do not use a pumped system.

Go to page 12 and look at figure 2. What they call a tempering tank can just be a water heater. You need a unit with two heating elements, upper and lower. Plumb the output from the heating loop to the top element orifice, and the lower element to the return. Plumb this "preheater" to the regular water heater as usual. 

Studying this link will give you some guidelines and a good place to start. Since your setup will be unique, there will be some trial and error involved. Looks like a fun project!


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## waverider (Jan 2, 2008)

I'm going to sleep on this idea for a bit and take a look around at hot water heaters.  I'd like to use a tank that is relatively compact - hence easier to elevate and place between the collector and the hot water heater.  
I'll let you know if and when I get to beta testing.  I'm mulling over how best to set up the tempering tank to test the performance of the collector - Want to put it in place, fill it and crank up the stove.  Theoretically, if the tank and collector are filled and the hot water output of the tempering tank that would normally feed the primary HW heater is left open (not connected to anything) I could safely test run the system without risk of pressurization. Then the performance of the system could be determined by measuring water temperature at the hot water output of the tempering tank.  

Thanks for the references.

Doug Simmons


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## Sandor (Jan 2, 2008)

Sounds like you have plan Doug.

Please keep me posted!


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