Pressurized and non pressurized thermal storage tank Sources

[peakbagger]

It looks like American Solartechnics is out of the unpressurized storage business (at least for now) per a post on their website. Too bad as I like my current one. I am starting to plan a new house and going to be looking for an 800 gallon unit. Its looking like the options are pretty limited for commercial units. Hydroflex seems to be in business but not a lot of other manufacturers are popping up. Tarm in Lyme NH seems to have swapped over to pressurized tanks although they did offer unpressurized previously. The ASTs and the Hydroflexs are nice as they go in through a standard door opening. Of course there is the modified propane tank option that many use but I would not feel comfortable installing one unless I had a way to swap it out which may not be an easy option.

So what manufacturers am I missing?

One of the options I am keeping any eye out is for stainless bulk tank used by small dairies to store raw milk. The small daries just can not compete so the tanks pop up on occasion but the maple sugar folks grab them for sap storage. I also have considered stainless IBC tanks that pop up on occasion.

 

[salecker]

What are your concerns about a repurposed propane tank?

 

[peakbagger]

They take up a lot of room for the volume stored plus they are dont stratify as well when used horizontally compared to a taller tank. They also increase the volume of the system considerably so larger expansion tanks are needed to deal with added expansion volume. Many folks on this site are quite happy with them so I am not dumping on them, just looking for options.

Hard to beat the rectangular AST tanks for volume efficiency, they are taller so better stratification plus they are made out of closed cell foam reinforced with galvanized sheet metal so they do not weight a lot. No rigging required just carry the pieces down the stairs and screw it together. If I didnt want more volume I would just move it.

 

[hobbyheater]

Smokeless Heat sells pressure tanks that will go through doorways .
I have the plans for building your own soft tank from my Jetstream days .

 

[coolidge]

Could you plan for some extra concrete in your build to build one in your basement. Insulate the crap out of it with foam board. EPDM liner.

 

[peakbagger]

The problem is the liner, EPDM is not rated for continuous immersion service at storage temps. The plasticizers "cook out" and they fail fairly rapidly. AST tried a couple of alternatives to PVC and went back to welded PVC and even that is limited to 180 F max.

Pressurized tanks can be steel and uncoated as the feedwater is constantly recirculated so the free oxygen is driven off pretty quickly. An unpressurized tank always has oxygen available so its got be a corrosion free interior like stainless or synthetic liner. There are some high temp epoxy based systems that can run over 250 F that can be applied to regular steel but the cost for the product makes buying a used stainless tank the current pick.

 

[coolidge]

Some light reading.

https://versaflex.com/wp-content/uploads/2014/09/ds-VF380.pdf

 

[peakbagger]

Thanks for the link. I am unsure if its the right product as there is no specific reference to immersion service. Maybe it will work but I would want to see it specifically give a temp rating for immersion. Plus it sounds like its going to be very expensive system for a small household tank. Belzona has several products rated for immersion but based on past experience the cost is steep.

 

[PassionForFire&Water]

But if you are building a new house you can easily plan for a pressurised tank.
800 gallon = 2 x 400 gal - ganned up in parrallell
or you have custome tank welded ASME or non-ASME

 

[PassionForFire&Water]

you can actually also keep good stratification as follows with 2 tanks; see image

 

[peakbagger]

That is definitely an option I am looking at. Two stainless IBC totes might be interesting, it will require a larger opening but I should be able to get a reasonable heat exchanger in through the top manhole.

 

[maple1]

No issues or regrets here after 10 years with my stacked 330 gallon LP tanks. Just wish I had more volume. But my space down there is limited.

 

[salecker]

2 500 gallon propane converted standing on end.Zero issues