Author Topic: My version of Gary's $1000 solar water heater  (Read 1832 times)

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jondecker76

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My version of Gary's $1000 solar water heater
« on: June 20, 2009, 11:46:08 PM »
I started on the $1000 solar water heater from builditsolar.com about a month ago. My time is very limited, and funds are limited as well, so progress has been slow, but consistent.


A couple of differences to note from the original design:



  • I want to make sure the tank is very strong, so I added an extra 2x4 perimeter about half way up the tank. I am also using a combination of glue, screws and carriage bolts on these corners.
  • I plan on using seam tape to build a perfectly square liner (not going with the folding technique). Time will tell if this ends up being a mistake or not, but I think testing this kind of liner construction technique is warranted.
  • I may also try using some bulkhead fittings after the liner is finished, and bring the pipes right through the liner. I haven't decided on this yet.
  • I will be using 4x4 treated lumber to build framing to keep the boxx off of my (damp) basement floor)


My house was constructed in 1881, so the ceilings in the basement are low (around 6' or so), and the doorways are small.  Not being the most pleasant of basements, I decided to do all of my lumber cutting outside, then assemble the tank in the basement. Since it is damp in my basement, I also plan to fully paint the box inside and out. While the painting would have been easy to do outside piece-by-piece, I wanted to make sure that the wood glue I'm using (Titebond III) would adhere to the wood well, so I decided to paint the box after it was glued and screwed together in the basement.


I was able to cut out all of the components for the box (water tank) easily in one afternoon using only simple tools (a 48" rule and a circular saw). I don't have a garage or a great place to work, so I did this all on the lawn.


After getting things cut out, I brought all the pieces into the basement and did a test fitting of all the pieces, tacking everything together with a few screws. I did this to ensure that everything would fit as it should, as well as to see where the best placement of the tank would be. Below you can see how the tank looked together and in place by my hot water tank.



I was pretty happy with how things looked and fit, so I began glueing and screwing the components of the box together. This part went pretty fast as well, and before I knew it I was ready for paint.


Surprisingly enough, the painting step was the most difficult part up to this point. Working part time on it, it took me over a week working a few hours a day. I painted everything inside and out with exterior paint. The entire thing took exactly one gallon of paint in 4 coats. Below are some pictures of the tank painting completed:







My next step was to find insulation. This was another step that I thought would be a breeze. I spent countless hours on the phone trying to fine anyone in my area that carried polyisocyanurate. I called every roofing place, lumber yard and home improvement warehouse that I could find in the Yellow Pages. With the exception of just 2 places, nobody even knew what it was. I was continually met with the response: "We got some styrofoam.....". I finally found a place that could get the 2" polyisocyanurate board I was looking for, so I drove about an hour away to go get it.


After some more measuring in the basement, I again went outside to make the cuts I needed. Because all of the corners in my tank were beveled and I didn't want to make complicated cuts, I decided that I would cut the polyiso a bit short, and fill in the gaps later with Great Stuff foam in a can.


Doing some cutting outside...


Laying the insulation in the tank...


A close-up of how I left a "gap" in the corners that will be filled with Great Stuff. I plan on climbing in the box and poking holes in the corner every 6" where I will fill the gap with foam...


Since my lid was just a flat 48"x48" piece of plywood at this point, I began ripping some 2x4's down to be 2 inches tall (1.5"x2"). My plan was to make a perimeter around the lid exactly 2" tall that will match up perfectly with the 2" polyiso insulation. Since my 48" rule was exacly 2" wide and 48" long, it made a perfect template for the pieces I was going to cut from the 2x4's.


My 48" rule made a perfect 2" template...


And here it is all glued and screwed...


Thats all I have done at the moment. My plan moving forward in the next week is to paint the lid and place the insulation in it, then line it up on the tank in the basement and drill 3 holes per side down through the lid and the upper perimeter of the tank, and use 1/2" carriage bolts 7" long to hold the lid down to the tank.


Also I received my MCP355 water pump in the mail this week along with firestone 45 mil EPDM liner 10'x15' in size. Note that this liner is too small for the folding method of using the liner. Again, I plan on cutting each panel out individually and using firestone's seam tape at all the joints and making a perfect box liner. I will be ordering the seam tape next week..


I'll post more updates as I progress with this. My goal is to have the complete system up and running before fall.

« Last Edit: June 20, 2009, 11:46:08 PM by (unknown) »

strider3700

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Re: Progress on my version of Gary's
« Reply #1 on: June 20, 2009, 11:12:59 PM »
I'm wondering what you've decided on material for the heat exchanger.  I'm assuming this will be plumbed in as a preheat tank?


Definitely keep us up to date it's looking good so far.

« Last Edit: June 20, 2009, 11:12:59 PM by strider3700 »

jondecker76

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Re: Progress on my version of Gary's $1000...
« Reply #2 on: June 21, 2009, 12:40:59 AM »
Yes, this will be primarily used as a pre-heat tank, though I when I plumb things I will have valves to bypass the normal water heater as well as this preheat tank. This will give me a variety of options. For example, during the summer months, I may decide to bypass the normal water heater all together.


The heat exchanger will be 300' of 1" PEX tubing per Gary's recommendations. The pex will hold 12 gallons of water, so the heat exchanger is pretty much 100% efficient for draws less than 12 gallons (with suffiecient recovery time in between draws, of course)

« Last Edit: June 21, 2009, 12:40:59 AM by jondecker76 »

CmeBREW

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Re: Progress on my version of Gary's $1000...
« Reply #3 on: June 21, 2009, 06:40:49 PM »
Great job on the Box Jondecker.


     I think I would reinforce the middle also just to be extra safe--especially with a taller box like that.

I was worried about one thing though-- are you certain that that Firestone Seam tape will not leak after many months under water pressure??  (I'm no expert on adhesives)


I've been trying to get my father to let me make a system like that for his house (3-person plus a lot of hot washing) , but he is like everybody else around in public, he does not want to anyup a little funds (I even lied and said it would only be $400) in order to have an awesome hot water solar system and big savings on the electric bill each month!!  But NOPE.


It's like banging your head on a brick wall. So since I have to pay for everything myself, (and I don't have many funds myself) , I am thinking about simply using a 50gal PLASTIC barrel that I have (with a couple of strong steel bands around it) as a nice preheater (with coil of 200' 3/4" pex inside it)  , and place it beside the electric hot water heater in the basement like you did.  


Except I'm just going to use some normal fiberglass insulation (With plastic on both sides) wrapped around it and then more plastic wrap around that.


I don't know if anyone ever tried anything like this before. The water in the plastic barrel would probably get 140F degrees the same as yours.


And then sequence the hot water from a collector outside like your nice system.

We'll see.


Anyway, keep up the good work on your nice 'Family size' system and keep us informed of the progress.

« Last Edit: June 21, 2009, 06:40:49 PM by CmeBREW »

Ungrounded Lightning Rod

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Why all this construction?
« Reply #4 on: June 21, 2009, 10:09:38 PM »
Just curious?  Why not use water heaters as insulated storage tanks?  They come in lots of sizes, are not particularly expensive, and are capable of keeping the water clean and pressurized.  Keeping water in a wooden box strikes me as a flood waiting to happen.  (But I might be biased from growing up in a cold place and having a remote house that is unattended for long periods in an area with hard freezes.)


(By the way:  It's "ante up".  "ante" (before) is the bet you make before the game starts to commit to playing in it.)

« Last Edit: June 21, 2009, 10:09:38 PM by Ungrounded Lightning Rod »

jondecker76

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Re: Progress..
« Reply #5 on: June 22, 2009, 06:24:40 AM »
RE: seam tape

Normally the EPDM liner is folded and put into the plywood box tanks to avoid having any breaks in the liner. I was going to do this, but I figured that it would be neat to try seaming one together with the seam tape that is made for t his application. The seam tape provides a bond that is stronger than the EPDM its self, and is specifically made to seam pieces together under water. Time will tell if it works in the hot environment of the tank. I just thought I would try to be the first to try it out and report my results. I'm hoping to have a better seal between the lid and the tank by getting rid of all to folds and wrinkles. I have also drilled weep holes in the bottom of the tank so that I will know if it starts leaking.


RE: Water Heater tank VS. EPDM Lined Box

The advantage of building your own tank from plywood is that you can choose both the volume of capacity as well as the amount of insulation. Even a large hot water heater tank at 80 gallons doesn't supply that much storage. My box, after accounting for the PEX coil and insulation, should have in the neighborhood of 350 gallons capacity to store the extra heat. The other advantage is that it lends its self to heat exchanger setups, so you can have single wall, double wall setups if you want. Plus, i can build the tank to exactly fit the space I have to work with.

Of course, there are obvious disadvantages as well - you can't pressurize them, you have to build them, they are likely more prone to leaks, they cost more than a used hot water heater would cost, etc. I guess its a decision that needs weighed out by the individual as to which would be best for them - but you have a good point in that getting a used hot water tank may be the way to go if it best fits your situation. (I have a family of 6, so I really need to capture a lot of BTU to try to offset a portion of our hot water usage)


I took a few close-ups of my lap joints to show how I used the carriage bolts for extra strength. I'm 100% confident that this tank will have no problems holding in th water pressure when its full.



« Last Edit: June 22, 2009, 06:24:40 AM by jondecker76 »

mbeland

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Re: Progress..
« Reply #6 on: June 22, 2009, 03:24:54 PM »
Nice work!


Your idea about seam taping the liner is interesting as it may be a way to further reduce the price of the system. How do you plan to apply the seam tape in the corners? That would be a place where risks of leaks could be more important.


Martin

« Last Edit: June 22, 2009, 03:24:54 PM by mbeland »

jondecker76

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Re: Progress..
« Reply #7 on: June 22, 2009, 04:51:36 PM »
My original thought behind the seam tape was to have nice mating surfaces between the tank lid and the top of the tank. Plus it just seems so much neater and more organized.


I ordered the seam tape today, and when added to the price of the smaller liner is still a bit more expensive than buying just a single bigger liner and folding it.


For seaming, I plan on using single-sided 6" seam tape both inside and outside of the liner (I.E. taping the seam on both sides). I will need to take special care in the corners as you have suggested. I am also looking for a very good bonding sealant to fill the corners with as well. I'm hoping that this will be enough to prevent any leaks from forming - but I haven't got to that part yet, so I will see what happens.


Worse case scenario is that it won't work and I may have wasted about $200, and will have to buy a bigger liner and use the fold technique. The bright side is that I have wasted more than this amount of money countless times in my life on useless stuff, so the worse case isn't all that bad. I do have high hopes of it working as planned though.

« Last Edit: June 22, 2009, 04:51:36 PM by jondecker76 »

CmeBREW

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Re: Progress..
« Reply #8 on: June 22, 2009, 05:44:45 PM »
It sounds like a worthwhile thing to try.  You may want to have a sump pump 'on standby' just in case a seam rips when filling it, to drain it as quick as possible.


If I ever get to make that nice big system design, I was going to do like Gary's and use the composite decking board around the top, but in addition to that I would use some of that soft (pink colored) foam house SILL insulation (comes in rolls 4,6,or 8" wide)  under and above the 6" wide composite decking board and tighten it down with screws or bolts for a perfect thermal seal.  


But as you said, when it comes time to actually DO it, it might be a LOT harder than just thinking about it or drawing ideas on paper.


It was nice of Gary to share this design and to tell about the PEX tubing being more reliable and about that neat little CPU water pump.  I never knew those existed. I just ordered a cheaper, lower power (6 watt) cpu pump from Hong Kong a few days ago to test it and see how it does with lift, etc.  (It is rated at 20k run hours/// but lift is only 8ft)  It is good to try things like you said.


I am certain You're really going to love the feelings you get every time the hot water spicket comes on from your entire family and the big savings on your electric bill.  The pay off will be big.

I know I do, just from my own daily SOLAR hot shower.  This just added to my addiction!    -Hope everything goes right.


-Thanks ULR for spelling correction.  I've used that phase a million times in life, but never actually needed to spell it before.  Also, I always ASSumed it meant a person who wouldn't pay up AFTER lossing a bet. But now it makes more sense to this application here. Serves me right for not being a gambling man.


 

« Last Edit: June 22, 2009, 05:44:45 PM by CmeBREW »

wooferhound

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My version of Gary's $1000 solar water heater
« Reply #9 on: June 22, 2009, 07:19:43 PM »
I haven't seen Gary's design before.

How do you get the water from your unpressurized preheat tank and into your pressurized House system to use it ?
« Last Edit: June 22, 2009, 07:19:43 PM by wooferhound »

jondecker76

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Re: My version of Gary's $1000 solar water heater
« Reply #10 on: June 22, 2009, 07:25:12 PM »
Gary's page on the $1000 solar water heater is located at:


http://www.builditsolar.com/Experimental/PEXColDHW/Overview.htm


Basically, the unpressurized water in the plywood tank is recirculated to the collector pannels, while a large volume heat exchanger (12 gallons) made of PEX carries the high pressure house water. Pretty nice setup, and has been fun to build so far!

« Last Edit: June 22, 2009, 07:25:12 PM by jondecker76 »

Ungrounded Lightning Rod

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Re: Progress..
« Reply #11 on: June 23, 2009, 06:32:35 PM »
Given that it costs MORE to cut the liner up and tape it (increasing the opportunity for leaks and the stresses) than to just fold one (eliminating any seams) I'd be inclined to stick with the folded version.


Re "ante":  You're welcome.  (When I first encountered it as a kid I thought it had something to do with an uncle's wife.  B-)  )

« Last Edit: June 23, 2009, 06:32:35 PM by Ungrounded Lightning Rod »

ghurd

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Re: Progress..
« Reply #12 on: June 23, 2009, 07:40:01 PM »
Re:Re:  I recall the day I learned the proper pronunciation of a certain derogatory description of another's mother had nothing to do with a brand of soda (7-Up).

The term related to a female dog or wolf was understood correctly.

G-
« Last Edit: June 23, 2009, 07:40:01 PM by ghurd »
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BigBreaker

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Re: Progress..
« Reply #13 on: June 24, 2009, 05:09:54 AM »
You could also tape the folded barrier edge down and have the best of both worlds.  No leaks and no water seeping up into the folds and stagnating.
« Last Edit: June 24, 2009, 05:09:54 AM by BigBreaker »

GaryGary

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Re: Why all this construction?
« Reply #14 on: June 24, 2009, 08:27:34 AM »
Hi,

The EPDM lined tanks have been used a long time, and actually have quite a good record.  I heard from one person who had one installed in the early 80's, and is still on the original EPDM liner.  They last longer if the temperature is kept at 170F or lower.  The cylindrical commercial version made by STSS is fairly popular and has a good reputation.


One nice thing about these tanks is that the liner can be replaced without having to scrap the whole tank -- so after 15(?) years you can install a new liner instead of having to buy a whole new tank.


The commercial hot water tanks with heat exchangers built in are actually pretty expensive, especially in the larger sizes.  If you get a standard large hot water tank, you would typically have to use an external heat exchanger, which typically means adding a 2nd pump -- not the end of the world, but another complication and expense.  And, as Jon said, its easy to do a tank that has more capacity than the typical hot water tanks.


Gary

« Last Edit: June 24, 2009, 08:27:34 AM by GaryGary »

g reif

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Re: My version of Gary's $1000 solar water heater
« Reply #15 on: June 25, 2009, 08:32:19 PM »
jondecker

what's the capacity of your tank?

I want a 800-1000 gallon one and my first chose is an old milk bulk tank but am having trouble finding one.

backup plan would be a tank like yours and gary's but oversized and taller. I would have a lot more supports around it and was going to bolt corners also

and painting with an epoxy paint


here's a place that makes custom liners

http://www.websweeper.com/liner/tank-liner/prices.php

« Last Edit: June 25, 2009, 08:32:19 PM by g reif »

Madscientist267

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Re: Progress on my version of Gary's $1000...
« Reply #16 on: June 26, 2009, 08:05:49 AM »
Nice work so far. I just have one question... Where does the idea of 100% efficiency come in?
« Last Edit: June 26, 2009, 08:05:49 AM by Madscientist267 »
The size of the project matters not.
How much magic smoke it contains does !

BigBreaker

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Re: Progress on my version of Gary's $1000...
« Reply #17 on: June 26, 2009, 09:42:50 AM »
The water in the pex coil lingers in the water tank for a long time between uses.  That equalizes the temperatures, which is 100% efficiency in the heat exchanger world.
« Last Edit: June 26, 2009, 09:42:50 AM by BigBreaker »

jondecker76

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Re: My version of Gary's $1000 solar water heater
« Reply #18 on: June 26, 2009, 06:07:25 PM »
My tank should have about 380 gallons of capacity.


Where are you located? My father has a 1200 gallon round bulk milk tank that I'm sure he would part with for about $500-$600 (he sold it on ebay 4 years ago to a winery that never showed up to get it). We both live in North Eastern Ohio.

« Last Edit: June 26, 2009, 06:07:25 PM by jondecker76 »

g reif

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Re: My version of Gary's $1000 solar water heater
« Reply #19 on: June 28, 2009, 06:12:02 PM »
i'm in wisconsin so that would be a road trip.


thanks

« Last Edit: June 28, 2009, 06:12:02 PM by g reif »