# Swimming pool as a storage tank?



## BrownianHeatingTech (Dec 11, 2007)

The suggestion was recently made to use an aboveground swimming pool frame for a hot water storage tank.  I think that's an interesting idea, except that I can't seem to find any pools in the 500-1000 gallon range, which is all that most people want in their basement.

Any help?

Thanks,
Joe


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## webbie (Dec 11, 2007)

That is not a bad idea - it is capable of holding the water, etc. - even an old hot tub is 400 gallons (mid-size).

A swimming pool would have to be insulated and/or lined, as the standard plastic is probably not designed for the high temps...

How much does even a new "soft tub" sell for? That is a hot tub with air insulated sides.


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## BrownianHeatingTech (Dec 11, 2007)

Webmaster said:
			
		

> That is not a bad idea - it is capable of holding the water, etc. - even an old hot tub is 400 gallons (mid-size).
> 
> A swimming pool would have to be insulated and/or lined, as the standard plastic is probably not designed for the high temps...
> 
> How much does even a new "soft tub" sell for? That is a hot tub with air insulated sides.



I don't think I'd trust the soft tub with the temp, even with insulation.  If it did boil over, the small mess would become a large mess once it melted a hole in the air bladder...

And yes, it would need a new liner.  EPDM seems to work well for folks.  Insulation wouldn't be required, but not insulating a heat storage tank would be pretty silly.

Joe


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## Eric Johnson (Dec 11, 2007)

There's about a million above-ground pools available online. The smallest one I could find was a 10'x14' oval, 48 or 52 inches high. Don't know what the water volume is.

http://www.familypoolfun.com/main.php?htmlPage=10x14_oval_pools


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## BrownianHeatingTech (Dec 11, 2007)

The smallest I've found was 48" high by 10' diameter.  262 cubic feet, or 1960 gallons.

For 1000 gallons, something 7.5' diameter (at 48" high) would work well.  That's just under 1100 gallons (figured for a 40" water depth, to give some room above the water line), leaving some room to add some insulation.

Joe


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## hkobus (Dec 11, 2007)

With the sizes pools come in I would be a bit concerned about losing the stratification in the storage. Pools are designed to have large surface area, for my storage tank I would rather have the same volume in a tall structure to get the benefit of stratification. In my mind with large surface, I would need more HX area in the top of the tank too.
I would like to go for 5 or 6 ft tall tank, any comments are welcome.

Henk.


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## BrownianHeatingTech (Dec 11, 2007)

hogstroker said:
			
		

> With the sizes pools come in I would be a bit concerned about losing the stratification in the storage.
> ...
> I would like to go for 5 or 6 ft tall tank, any comments are welcome.



I would, too.  But the height becomes an issue in a typical basement (getting the heat exchangers in - and out again, if they need service), and the structural integrity of the tank becomes an issue as the pressure mounts due to depth.

I think most customers will see the cost/benefit ratio working out best at a 4-foot depth.

Those who want the taller tank, which may offer a couple percent better performance, will likely end either with steel tanks or cast concrete cisterns.

Joe


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## Jags (Dec 11, 2007)

Once again, probably speaking out of line, but......
If someone was looking for a few hundred gallons of storage, with all the oil burners out east, why couldn't a several hundred gallon oil tank be used?  Its designed to fit through doors for basement installs, designed for fluid storage (round corners and all that), structurally sound, and could be insulated by a spray foam application. Comes with pipe fittings and usually its own legs.  Once cleaned of old fuel oil, if mods needed to be made to the tank, simply weld or braise your new fittings to the tank. 

Not sure of the practicality of the idea, but if you needed more storage, add another tank and run pipes between them.  I know that there has to be a down side, cuz I can't be the first person to think of it.  Just an idea.


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## BrownianHeatingTech (Dec 11, 2007)

Jags said:
			
		

> Once again, probably speaking out of line, but......
> If someone was looking for a few hundred gallons of storage, with all the oil burners out east, why couldn't a several hundred gallon oil tank be used?  Its designed to fit through doors for basement installs, designed for fluid storage (round corners and all that), structurally sound, and could be insulated by a spray foam application. Comes with pipe fittings and usually its own legs.  Once cleaned of old fuel oil, if mods needed to be made to the tank, simply weld or braise your new fittings to the tank.
> 
> Not sure of the practicality of the idea, but if you needed more storage, add another tank and run pipes between them.  I know that there has to be a down side, cuz I can't be the first person to think of it.  Just an idea.



I've considered it.  Problem is the cleaning the old oil part.  Start to subject old oil to 200-degree water temps, and it will out-gas a lot of nasty chemicals.

The tanks also aren't all that rust-proof, unfortunately.  Rust-out is the typical reason a tank is replaced.  I could get a properly-designed heat exchanger through the top ports, but it does limit the heat exchanger choices.  The legs would help with keeping it off the floor, for reduced heat loss.

Tipping it on-end and cutting the one end (now the top) off might work, although I expect you'd need a brace or two to keep it from spreading.

I'm thinking that the horizontal tanks might be the best choice.  You could cut a round hole in the flat top, without weakening the structure much, and that would allow a larger heat exchanger to be installed.  Of course, stratification would be about zero.  However, one could stack the tanks on a frame and use the top tank for recovery and the bottom tank for charging, with a decent-sized pipe connecting them so the water can convect as it heats/cools (need to weld a bung into the bottom of the top tank).  That mandates a sealed penetration for the lower tank's heat exchanger, as it will be under the water line.

All sorts of possibilities.  I think that the swimming pool idea may be the "best bang for your buck" and the most attractive to my customers for that reason.

Joe


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## Eric Johnson (Dec 11, 2007)

Well, new 250-gallon oil tanks go for about $250 at Home Depot, as I recall, so you're right at $1 a gallon, which seems to be what the DIY alternatives all go for, more or less, from swimming pools to propane tanks to DIY sheet metal and wood affairs. I think corrosion might be a problem in a nonpressurized tank, though I bet you could treat the water. Might be perfect if all you wanted was 250 gallons, but I expect that trying to tie two to four of them together wouldn't yield the same results as a single, 500 or 1,000-gallon tank. But as with everything else, I could be wrong on that, too.


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## Jags (Dec 11, 2007)

Ahhhhh.....the rust factor.  See, I knew it was too simple.  And I can also see that stacking tanks would limit the natural stratification of the water column.  With out even asking, I am going to assume that you guys have exhausted the poly tank options.  I would imagine that cost would be a major factor in those (maybe heat as well).


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## hkobus (Dec 11, 2007)

Jags,

I looked at poly tanks, as we use them for storage of fertilizer and such, but as you suggested the temp is the issue. They recomend less than 120 F and peak temp at 140 F (less than 10 Min). The price is right, at below the $ 1 per gallon here, and many used shapes and sizes available.

Henk.


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## Jags (Dec 11, 2007)

hogstroker said:
			
		

> Jags,
> 
> I looked at poly tanks, as we use them for storage of fertilizer and such, but as you suggested the temp is the issue. They recomend less than 120 F and peak temp at 140 F (less than 10 Min). The price is right, at below the $ 1 per gallon here, and many used shapes and sizes available.
> 
> Henk.



Ever see this one?  http://www.rainkeepertanks.com.au/polytanks_rainhaven.php  (grand daddy slim)

Not making any suggestions, and I am not sure of details, but they make those things in all sorts of shapes that I have never seen.


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## Tarmsolo60 (Dec 11, 2007)

have any of you priced an stss tank? when I bought mine from tarm I think it was $1700(without hx), it came in a pretty easy "snap together" form. It had the raceways to get the pipes into the tank and had all the silicone and screws to assemble and seal everything. So, I was under $2 per gallon for insulated storage that had a warranty. I seems like it would be hard to beat if your paying $1 per gallon, then insulating it, plus all the messing around getting it figured out and hoping its going to work ok. I know sometimes half the fun is figuring things out and building them yourself and saving money, but, by the time your done you might not be as far ahead as you think DIY. If a nice used tank like nofossil has presents itself at the right time I would jump on it for sure and use it. Maybe STSS knows what it would cost to assemble a new similar tank and has theirs priced so its not really worth it to DIY. 

also, if your trying an old oil tank don't use it in a pressurized system it's not strong enough, use Hx's


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## Eric Johnson (Dec 11, 2007)

That's what I thought, too. The quote I got from STSS was $1,945 for the 957-gallon tank. The price for a tank plus hx for my system netted out at just under $5,500 including freight.

I'm sure it's worth it, but I knew I could do it for a lot less. Maybe not as good, but probably good enough for my needs.

That's probably why most gasifier manufacturers tend to downplay the need for a tank.


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## Tarmsolo60 (Dec 11, 2007)

I bought mine a couple years ago thats probably why it is $200 more now. So with the prices you just stated it seems like trying to save money on Hx would be a much bigger benefit than what you would save on the untested tank. I didn't buy my coils from them, they wanted $500/180' coil  at the time. I figured I could make them cheaper, and I could have if I would have done them then. I waited and copper didn't get cheaper. I ended up buying soft L and making them.

So knowing you can buy a 957 STSS for $2000, how much cheaper can you construct a insulated tank around 1000 gallons?


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## Beno (Dec 11, 2007)

How come a 120 gal Indirect costs as much as 900 gal tank with hx ? What does the Indirect have that the sorage tank doesn't?


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## Eric Johnson (Dec 11, 2007)

Tarmsolo60:

In my case, using an existing poured concrete cistern and some cinderblocks, surface bonding cement, etc., about $500. That's with 2" foam insulation all around and a EPDM pond liner. And a lot of time and effort, which I'm more than happy to spend in lieu of cash.

I probably have another $500 worth of materials in the heat exchangers, but some of that was materials that I had onhand.

Bear in mind that none of this is actually working yet, so I'm not crowing about it just yet. Hopefully this weekend.

Another guy here has a thread in which he describes how to build a similar tank to the commercial versions for around $700 in materials from the big box store.


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## BrownianHeatingTech (Dec 11, 2007)

Beno said:
			
		

> How come a 120 gal Indirect costs as much as 900 gal tank with hx ? What does the Indirect have that the sorage tank doesn't?



Ability to hold pressure.

The STSS (and other) storage tanks are open - no pressure other than the weight of the water.

The indirect is a sealed pressure vessel, and can handle at least 100PSI, usually more (most seem to be tested to 300PSI).

Joe


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## Beno (Dec 11, 2007)

Sorry, but what is the pressure needed for? And if it's needed, how come a large storage tank doesn't need it?


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## BrownianHeatingTech (Dec 11, 2007)

Beno said:
			
		

> Sorry, but what is the pressure needed for? And if it's needed, how come a large storage tank doesn't need it?



The pressure in the indirect is the pressure created by your well, which pushes the drinking water up into your house.

The large storage tanks use a copper coil to heat the water.  The water in the tank never mixes with the water inside the coil - it just sits there, so it doesn't need pressure to move it around.

Joe


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## Tarmsolo60 (Dec 11, 2007)

Eric,
   I saw the pics of your cistern and would be doing the same thing as you if that was in my basement. I was talking about someone who had to go out and buy a tank. It looks like you could build a duplicate of my tank cheaper than $2000 but as for using a different tank or swimming pool new and making it work I don't think you would be that far ahead of the game.


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## Eric Johnson (Dec 11, 2007)

As I understand your question, Beno, it's one of life's big trade-offs:

Pressurized Storage: No heat exchanger needed, because the tank is part of the heating system and the water it contains flows through the boiler and into the house zones, etc. Because the system water becomes oxygen depleted, corrosion is not a problem, so you can use a steel tank, fittings, etc. But the bigger the tank, the more substantial it has to be in order to hold the pressure. That much additional water in your system also requires a pretty substantial expansion tank--not something an Extrol 60 can handle. So what you save on the hx is offset to a large degree by the cost of the tank and expansion capacity.

Non-Pressurized Storage: The water in the tank is not part of the system, so it is not under pressure. It contains some oxygen, which can be a concern. And you need an expensive heat exchanger to move the heat around. You can use any tank that can take the heat, though you probably want to stay away from steel unless special precautions are taken with water treatment.

There are issues of stratification, etc. that I don't understand well enough to describe, other than to say that you have more flexibility with nonpressurized storage, depending on how you pipe and position the heat exchanger(s) in the tank.


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## Eric Johnson (Dec 11, 2007)

Tarmsolo60 said:
			
		

> Eric,
> I saw the pics of your cistern and would be doing the same thing as you if that was in my basement. I was talking about someone who had to go out and buy a tank. It looks like you could build a duplicate of my tank cheaper than $2000 but as for using a different tank or swimming pool new and making it work I don't think you would be that far ahead of the game.



I totally agree. Other than saving money, one of my big motivators is (hopefully) the satisfaction of designing something and making it work. It's all part of the decision process, but it's nice to see people thinking creatively. Here's a pic of my homemade hx--half of it, anyway, sans fittings.


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## verne (Dec 11, 2007)

with the price of hx I will definitely go with pressurized tank .any thought if burrying one would be better than just insulating it in the barn . I know it frees up space for wood storage. maybe the heat from the boiler would help it more?


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## Beno (Dec 11, 2007)

Do you ever need to replace the water you have in the Non-Pressurized Storage tank with clean water? How do you prevent bad things developing there (E-coli etc)?


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## Eric Johnson (Dec 11, 2007)

I think burying it makes sense with enough insulation.

A nonpressurized tank should be sealed, IMO. First, to keep it from becoming a huge humidifier, and second, to keep bad stuff out. They can go bad on you, and I'm told it smells pretty bad, but I don't think it's a major problem for most people.


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## Nofossil (Dec 11, 2007)

Beno said:
			
		

> Do you ever need to replace the water you have in the Non-Pressurized Storage tank with clean water? How do you prevent bad things developing there (E-coli etc)?



I have a non-pressurized tank. I used bromine-treated water to start with, and I have a layer of paraffin melted onto the surface to minimize evaporation. Probably acts as an antibacterial seal to some degree. I have an EPDM sheet caulked to the tank lip as well. I heat it to 160 degrees, which ought to discourage bacteria. I haven't looked at it since I put it in more than a year ago. Probably will open it this spring.


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## Eric Johnson (Dec 11, 2007)

I've always wondered about your paraffin layer, nofossil. I assume it's liquid most of the time, no? It sounds like it would make a mess on an EDPM liner, but I'm thinking about doing it. Better yet, how about a couple cans of Udder Balm?


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## Beno (Dec 11, 2007)

I guess you need some kind of drainage to be able to take the water out of the non-pressurized tank when you want to replace it, or service the tank. This is probably not good for the septic system.
Is there the same problem with the indirect? Is it easier there to replace the water?


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## Tarmsolo60 (Dec 11, 2007)

Eric Johnson said:
			
		

> Tarmsolo60 said:
> 
> 
> 
> ...



Thats a neat looking heat exchanger. what did you use a step drill? Phoscopper for solder? You will quickly get used to loading on your schedule not the boilers when you get that online. I made a fire Last night around 9:00 pm and its now after 4:00 pm and the top of my tank is still 140


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## Tarmsolo60 (Dec 11, 2007)

Beno said:
			
		

> I guess you need some kind of drainage to be able to take the water out of the non-pressurized tank when you want to replace it, or service the tank. This is probably not good for the septic system.
> Is there the same problem with the indirect? Is it easier there to replace the water?



I emptied mine once and just used a little surface pump like you would for a hot tub.

Are you talking about an indirect water heater, that would just be domestic water in the tank. other than the Hx boiler water.


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## Eric Johnson (Dec 11, 2007)

I used a step drill on a drill press and silver soft solder. The general consensus among the pros is that it won't hold up and I should have brazed it. But I'm a stubborn cuss and I'm going with what I've got. There are two identical units working as separate hxs--one for heat storage and one for recovery. Assuming that one is the storage hx, the recovery unit will nest down inside this one, but rising up to near the top of the tank. The piping on both will be reverse return to ensure equal distribution of the heat.

I'm really looking forward to getting it going. Running my boiler without it works fine, but the advantages to having that extra storage capacity are obvious, especially where summertime DHW is concerned.

You made the mistake of expressing interest. Here's a few more pics.


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## Nofossil (Dec 11, 2007)

Eric Johnson said:
			
		

> I've always wondered about your paraffin layer, nofossil. I assume it's liquid most of the time, no? It sounds like it would make a mess on an EDPM liner, but I'm thinking about doing it. Better yet, how about a couple cans of Udder Balm?



Paraffin is barely solid at the coolest temps that my tank ever sees, and that's OK - think about old-style canning. If I ever need to drain it, the paraffin becomes easy-to-handle chunks, I hope. I also wanted something that didn't have any volatile components.



> I guess you need some kind of drainage to be able to take the water out of the non-pressurized tank when you want to replace it, or service the tank. This is probably not good for the septic system.
> Is there the same problem with the indirect? Is it easier there to replace the water?



Yeah, a drain would be good. I have one, but you could siphon it out as well. The bromine treatment is basically same as a hot tub, which is where the water came from. If I ever drained it, I'd just run it out on the ground. You wouldn't want to replace the water in a pressurized system because every time you do, you introduce more dissolved oxygen that eats away at your steel and iron components.


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## Eric Johnson (Dec 11, 2007)

I decided not to put a drain in mine, because I didn't want to cut a hole in the liner. I'm thinking more along the lines of dropping a sump pump into the tank if I ever need to drain it. But a siphon would work, too.


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## kuribo (Dec 11, 2007)

I like the idea of using the cistern- I will be using three of my basement walls and building another to connect them to make a cistern of sorts when I go online with my boiler/hydronic/storage system.

One thing I am wondering about is if you used any rebar in the blocks and/or filled them with concrete. Mortar and surface bonding alone would keep me awake at night...


Chris
SW Wi


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## Eric Johnson (Dec 11, 2007)

No, no rebar. The blocks are filled with vermiculite. I plan to rest the weight of the house on the wall with a jack and some framing. I can brace the whole works against the foundation, which is about 6 feet away, if I see cracks developing in the bonding cement surface. I do have a Plan B if this all fails.

Welcome to the Boiler Room, by the way, kuribo.

What kind of boiler do you have or plan to get?


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## Beno (Dec 11, 2007)

I guess there is no advantage in buying an indirect 120 gal for $5000 if, for the same money, I can buy a 600 gal storage tank. If I'll manage to enter all these in my utility room on slab on grade, I guess I'll need an aditional post/footing under the slab, where the utility room will be.


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## kuribo (Dec 11, 2007)

I would think that adding rebar and filling the cores would be much easier, neater, and effective, but then what do I know....Simply placing weight on the wall may lead to other issues...Be careful!

I do not have a gasifier yet, but plan to cast some pieces to convert a used Royall boiler I picked up into a Seton style boiler. I also plan to have a masonry heater in the house with hydronic backup/augmentation.

Ultimately, I hope to have several heat sources (masonry heater, boiler, solar panels) all dumping into a 1000~2000 gal tank, which will then feed the hydronics, bathtub, domestic hot water.

This site is a great resource!

One question for nofossil (great site by the way!)...what is your btu/hr heat loss at your design point of your home?

Thanks all...

Chris
SW WI


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## Eric Johnson (Dec 11, 2007)

I think the rebar in the blocks is an excellent idea. Wish I'd thought of that before filling them with vermiculite, but that stuff does flow, so it might come out with a few strategically placed holes at the base. I'll have to see if I have enough headroom to put the rebar in now.


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## kuribo (Dec 11, 2007)

Ideally, you would drill a few inches into the concrete floor every 12" or so, lay your first course, stick in the rebar with some epoxy, then fill the blocks with concrete. You can then lay the next course, repeat.

The problem you may face is that concrete block walls, while strong in compression (they support perpendicular loading well) are very very weak in tension, which is what you will get with the side loads. There is very little force required to move a block wall side ways.

You might consider forming up a 3-4 inch thick rebared poured wall inside your cinder block wall. If you tie the rebar at the ends into the existing concrete walls, you should be ok....

Chris
SW WI


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## Eric Johnson (Dec 11, 2007)

Instead of pouring a wall, what do you think about building a 4-foot block wall filled with concrete right in front of the existing wall, using rebar like you suggest and tying a couple of horizontal pieces of rebar, sandwiched between the blocks, into the existing concrete walls?

BTW, which Royall model do you have? Are you using Seton's build-your-own kit, or something homemade?


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## kuribo (Dec 11, 2007)

Building a wall behind it as you mention, provided it is filled with concrete and rebar, should be fine. I would think though that removing the wall already in place would be a simple task if you choose to (re) do it....Be sure to drill into the floor and epoxy the rebar a few inches into the concrete...

The Royall is the mid-sized model, pressurized inside boiler. I will homebrew the refractory pieces to build a 2 chamber firebox which vents the combustion gas outside the firebox along the walls next to the water jacket, up, across the top, then down along the back like the Seton. Should work fine. Time will tell. I will not be able to get to this till next summer....

Take care-


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## leaddog (Dec 11, 2007)

Tarmsolo60 said:
			
		

> I bought mine a couple years ago thats probably why it is $200 more now. So with the prices you just stated it seems like trying to save money on Hx would be a much bigger benefit than what you would save on the untested tank. I didn't buy my coils from them, they wanted $500/180' coil  at the time. I figured I could make them cheaper, and I could have if I would have done them then. I waited and copper didn't get cheaper. I ended up buying soft L and making them.
> 
> So knowing you can buy a 957 STSS for $2000, how much cheaper can you construct a insulated tank around 1000 gallons?



My 1200 gal tank cost very little as it was made with materials that I scrounged at autions and yard sales. 
Tank frame and insulation (old walk in freezer panels,4in foam)------$20
old carpet padding to protect epdm-----free
spray foam to fill cracks etc,---------free with rebates from menards
epdm-------$180
1-1/2 pipe and fittings for bottem hx.------$25
Stainless top hx 1/2in finned with fittings$40
steel reinforcing $20
6in temp guage----$1
6 blocks of parifin ( ideaThanks to nofossil)----$12
Water treatment----$100
LOTS of time and thought and redoes------FREE as I'm retired
leaddog


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## BrownianHeatingTech (Dec 11, 2007)

leaddog said:
			
		

> My 1200 gal tank cost very little as it was made with materials that I scrounged at autions and yard sales.
> Tank frame and insulation (old walk in freezer panels,4in foam)------$20
> old carpet padding to protect epdm-----free
> spray foam to fill cracks etc,---------free with rebates from menards
> ...



Could you post a picture of your tank?

Thanks,
Joe


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## Eric Johnson (Dec 11, 2007)

Thanks for your help and advice, Chris. The cistern is actually 2,500 gallons. If I decide to tear the wall out, I'll probably just buy some more insulation and a bigger pond liner and turn the whole thing into storage. It's what I should have done in the first place. That's Plan B. Part of the cistern wall was torn out so that a previous owner could access it to dump trash and coal ashes, so I'll have to build another wall no matter what, but by doing it right this time, I'd get the benefit of a lot more storage which I've come to learn is a very, very good thing. So all things considered, it may be worth the effort and expense. Doesn't change my heat exchanger strategy at all.

The reason I asked about the Royall is that I ran a 6150 for 3 years and was impressed with everything about it except the inefficiency and smoke. I'll be interested in following your progress if you decide to document it here.


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## kuribo (Dec 11, 2007)

Yeah, it is always best to redo things if necessary to get them right- it is always more trouble and hassle to redo things down the road. I am in the middle of building a traditional Japanese timber frame home and I speak from experience here!

I will surely let folks know how the conversion works with the Royall. I bought it because it was built like a tank and looked simple and easy to modify...


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## Eric Johnson (Dec 12, 2007)

I was just down there poking around again, and it's kind of exciting to think about the possibilities, but also kind of a bummer when I think about tearing down the wall. I'm not discounting anything, because I'd seriously like to expand the tank, but since it's so close to being done, I'd like to test out everything with the smaller tank for awhile.

So I'm thinking about quick & dirty ways to do that for the time being, that won't make expansion harder down the road.

If I filled the other side of that cistern up with plain water, say up to 4 feet on the existing wall (I think it's 5 feet tall), that would sufficiently support the wall, don't you think? I could actually use a cistern for our greenhouse (flat roof drained into this one at one time; now the flow is diverted into a leachfield with plastic drain pipe). But even if the water just sat there, it would be a pretty cheap, sure-fire way of making sure everything stays where it should.

Maybe bracing it against the foundation wall with planks and plywood makes more sense. If I wanted to brace that wall with, say, vertical 4x4s braced with 4x4s against the facing wall, what kind of spacing do you think would be best? It's about a 7 foot span.

Obviously just thinking out loud here, but any thoughts, observations or polite suggestions would be appreciated.


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## kuribo (Dec 12, 2007)

The time you spend trying to work around things will probably take as long as just redoing it. Adding water takes time, then you have to pump it out. With the humidity and other issues it will present, it really isn't an ideal solution. Bracing will take time too and end up being something you will redo, never mind the risks. As my German machinist Grandfather used to say, if it's worth doing, it's worth doing right.....

I would just bite the bullet and redo it the way it should be done....It doesn't take long at all to demo a cinder block wall....But I know it is hard to tear down something that took time and effort to do...just think about how much time and trouble you will have if that wall springs a leak!

Whatever you decide, good luck with it!


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## Tarmsolo60 (Dec 12, 2007)

leaddog said:
			
		

> Tarmsolo60 said:
> 
> 
> 
> ...




well that is much cheaper....the discussion earlier in the thread people were talking about purchasing different kinds of new tanks that ran about 1$ a gallon than making them insulated. I still think there is no new "factory" type tank you could buy, insulate, and make much cheaper than a STSS. I think you could duplicate the STSS tank and save some money, It doesn't look like the material for one would be outrageous, as for labor I usually take some of mine into account because I could be out working doing the same type of thing(plumbing/electrical contractor) and making money. I do admire the ingenuity of people that have the time and skill to build useful things and save money at the same time. I like you like making things work.


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## leaddog (Dec 12, 2007)

Eric, If it was me I think I would fill the other side up with water for this winter and fine tune your system. the water would brace the wall and you shouldn't have any problem. Then this spring you could drain it with a sump pump and make any changes. It doesn't take long to drain with a sump pump, (redo) as I drained mine twice. The only problem I can see might be water migrating through the wall and wetting your insulation and lossing heat that way. If you rip out the wall and expand it you will have to splice the epdm but that might be easyier now  than when you have had water in it. I wouldn't be afraid to splice it as it is in a hole and if you had a very small hole that didn't seal it wouldn't cause a problem. The bracing should be easy, just place a sheet of 3/4 plywood against The wall and then about 4 braces against the other wall will hold it.
leaddog


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## Eric Johnson (Dec 12, 2007)

Thanks to both of you, and my apologies, Joe, for completely hijacking your thread.

I wondered about splicing the liner, leaddog--that was one thing I wondered about. I've seen the materials for sale, but I wasn't sure it could be counted on. I'll do a little more research.

Tarmsolo60, it's great to have another heating pro on the board.


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## leaddog (Dec 13, 2007)

BrownianHeatingTech said:
			
		

> leaddog said:
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> 
> 
> ...



here is a couple of pic of my tank. it doesn't show too much. If you look at the ends you can see the thickness of the panels. 
leaddog


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## EForest (Dec 15, 2007)

lots of great info here. I've been planning to turn a 16x20 deck built on piers into a sun room but after reading these threads would consider adding a full basement below (i have a walkout basement). this would allow the construction of an indoor storage tank partially below grade to footing depth with @ 3' above grade. I would use poured concrete and the tank could measure @4' x 16' x 6' deep. The ceiling would be 5' above top of tank for easy HX removal/replacement.
I would use the remainder of the space for wood storage and a gasifier (still can't decide which to purchase).
the home brew HX that Eric designed seems to be the way to go in such a long tank as I could build them to any length.
Any thoughts or advice would be appreciated.


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## Eric Johnson (Dec 15, 2007)

My advice would be to wait and see how mine holds up. I think it's going to work great, but that's not a universal opinion, and some of the naysayers know a lot more about it than I do.

But I spent part of my youth living and working on a farm. We made things work.


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## Eric Johnson (Dec 16, 2007)

Tarmsolo60 said:
			
		

> leaddog said:
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> 
> 
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There's a great thread around here describing how to make a STSS-style tank with stuff from Home Depot for around $700.


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## EForest (Dec 16, 2007)

do you recommend I insulate inside or outside of the concrete walls of the tank.
I've read that concrete acts as a thermal mass great for heat retention.
I'll assume there are plenty of high temp epoxy sealers on the market to finish the inside of the tank.
If not then an EPDM liner would last forever.


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## Nofossil (Dec 16, 2007)

gasifierwanabee said:
			
		

> do you recommend I insulate inside or outside of the concrete walls of the tank.
> I've read that concrete acts as a thermal mass great for heat retention.
> I'll assume there are plenty of high temp epoxy sealers on the market to finish the inside of the tank.
> If not then an EPDM liner would last forever.



EPDM seems to be the weapon of choice - the temps in a storage tank represent a pretty hostile environment for any sealant.

I'd insulate wherever it's easiest. Concrete adds thermal mass, but not very much compared to water. I'd make my choice based on whichever configuration was easiest and best at reducing insulation gaps and heat loss. You'll want as much insulation as you can get, especially above the top.


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## Burn-1 (Dec 16, 2007)

gasifierwanabee said:
			
		

> do you recommend I insulate inside or outside of the concrete walls of the tank.
> I've read that concrete acts as a thermal mass great for heat retention.
> I'll assume there are plenty of high temp epoxy sealers on the market to finish the inside of the tank.
> If not then an EPDM liner would last forever.



Since it's pretty germane to the topic, I'll recycle a link from one of my pre-Boiler Room era posts to a Tarm installation and tank construction where the user built a concrete tank and lined it with swimming pool epoxy paint.


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## EForest (Dec 16, 2007)

those are well engineered tanks, thanks for the link.
Now I realize the need for insulation inside my tank design. The walls will be poured along with the room foundation.
The form ties will remain in concrete after forms are removed leaving many possible seal failures.
insul with epdm inside should resolve that problem. 
You're right Nofossil the easiest insul job is the smart choice.
Thanks for all the insight.


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## Eric Johnson (Dec 16, 2007)

If you look around, there's a thread showing some pics of my concrete tank with insulation.


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## jebatty (Jan 3, 2008)

Good news first -- I picked up three used 275 gal fuel oil tanks, cleaned them out as best I could, and then plumbed them in series, with expansion space, resulting in about 800 gal storage. I pd $125 for the tanks; tank plumbing and other issues related to plumbing were perplexing, but solved - and the price was right. I use a plate heat exchanger so no need to try to make one to fit inside the tank(s).

Better news -- what about a septic tank? Capacity is around 1200 or more gallons; price around here is about $700; and now also available preinsulated (don't know cost). Bury the tank, designed to hold water without leaking, good access manholes. Easy to fit an exchanger in the tank or use a plate exchanger. Very likely this is where I am headed next summer to prepare for winter 2008-09.


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## Reggie Dunlap (Jan 3, 2008)

I considered a pre-cast septic tank. My plan was to buy the lower half of a 1500 gallon tank and install it so the top was flush with my basement slab. I think it's a good idea that's probably only practical in new construction. Instead I built a 750 gallon tank out of concrete block, but I kind of wish I'd used a septic tank because it would take up no space in my basement. The only reason I didn't do it was because I was in a hurry to get the first floor framed and I hadn't quite worked out all the details in my head.


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## MrEd (May 10, 2008)

Any other opinions on used oil tanks as a heat storage?

I have 4 new'ish 330 gallon oil tanks, already in my cellar. (less than 10 years old)

Obviously if I go forth with my Tarm Solo purchase, I won't need a 1400 gallons of oil in my cellar anymore.

Seems like if there was an easy way to convert 3 of them to heat storage, it would be a win-win-win. (they are free, it would get rid of 3 unused tanks taking up space, and they are already in the cellar)

Opinions? How hard will it be to clean them? How will they be fitted with a heat exchanger?


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## Nofossil (May 10, 2008)

I've heard that they're really hard to get clean, and they're not designed to be pressurized. Means you'd need a flat plate HX or some such.


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## TCaldwell (May 12, 2008)

I have 2 275 gal horizontal oil tanks plumbed in series, inline between the garn and the flat plate hx, located in a basement crawlspace. My system pressure is atmospheric and generated by headloss and pump curve, with 1 taco 13 on the supply side, i would run 13gpm at 9.5 psi, adding a second matching circ on the return to the garn i run 17gpm at 6 psi. I believe most oil tanks are ul rated for 5 psi, I called crown tank mfg co, they stated that they randomly pressure test their tanks to the point of bursting, what i was told is that a standard 12gauge oil tank that they sell to home depot will start to deflect at 12 psi and will burst between 15 and 35 psi. So i installed a 9 psi relief valve in one of the oil tank bungs for protection, as to rusting , in the garn's unpressureized tank i use a nitrite based oxygen scavenger,so i added the corresponding ammt for the oil tanks and monitor. My justification for the second circulator was for the flexibility in firing times with the added storage, i  installed these last november, so far so good.


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