My stab at building heat storage

[Yule log]

The first post was so fun I couldn't wait to try another.

Even though we haven't started on our next home, I thought I would take a stab at building a heat storage tank. It is based on structural insulated panel construction. I figured if homes could be built out of SIPs then tank sides would work also. The tank will be 8' long, 4' high and 4' deep. The foam is 3.5" thick and has an R value of 24. It is amazing how hard the foam gets when it sets up. My first panel uses OSB as skins but I think aluminum sheet would work just as well and would look better (at 10X the cost of OSB). I've attached a photo of the first piece.

I'm planning on using an HDPE liner and building an insulated top. After looking at the cost of currently marketed pieces, I figure I will have a sturdy, well insulated tank that will cost 1/4 the amount of other tanks. We'll see how it works!

 

[Gooserider]

Looks good as a panel, but I'd be somewhat worried about how well that type of construction holds up under tank pressure, unless you are planning to do an external frame with lots of 2x?s to support it. The pressure at the bottom of the sidewalls is going to be extremely high, so you will need lots of support to keep it from blowing out in the middle of the long sides - I don't know how much strength you get from the foam panel design, but the plywood and 2x? designs I've seen all need extensive bracing.

Gooserider

 

[Yule log]

Yeah, I've wondered about the same thing. I will play with the design before I fill it. I have seen some very impressive strength charts that compare foam filled walls to stick built walls. Not sure how much this carries over to water tanks. I would like to put some strapping/cable across the lower inside of the tank but that would mean I would have an opening in the liner. Hmmmm.

 

[leaddog]

Looks good as a panel, but I'd be somewhat worried about how well that type of construction holds up under tank pressure, unless you are planning to do an external frame with lots of 2x?s to support it. The pressure at the bottom of the sidewalls is going to be extremely high, so you will need lots of support to keep it from blowing out in the middle of the long sides - I don't know how much strength you get from the foam panel design, but the plywood and 2x? designs I've seen all need extensive bracing.

Gooserider

I built my tank from walkin freezer panels which are about the same as the ones you made. They are steel/4infoam/steel. I had to reenforce them at the bottem and top. They started to bow both ways. There is ALOT of pressure from the water. The temp also made them deform more also I think. What you are doing will work just put a stong framework around it to hold the pressure. 2x6 on edge around top, middle, bottem should do it.
leaddog

 

[steam man]

I kind of have an alternative plan to construct a tank if I don't find one that I want. Basically a taller cylinder style for improved stratification and saving space. I made a similar version for a concrete foundation form years ago that was 8' high. There was a lot of pressure. It was nerve wracking watching the forms just start to bow (I was a little cheap on something that wasn't going to be permanent). Everything held but I think I could definately improve on that idea.