Thermal Storage Tank, part 1  6

Solar heat

Solar heat

For our zero-energy building we are using the sun to provide ALL of the heat we will need throughout the winter. After months of discussion, engineering models of heat requirements, heat losses, heat storage and solar heat generation… the team came up with a system. There are three major ingredients:

  • Solar collector
  • Thermal storage tank
  • Super insulated house

The Solar Collector generates the heat from the sun; the Thermal Storage Tank holds the heat for when it is needed; and the well-insulated house uses only the heat it needs.

Today we began the construction of the thermal storage tank.

The company providing the technology for the tank is TSS, Thermal Storage Solutions. Today they are still building these storage tanks to custom sizes on site. In the future they will have pre-fabricated tanks that just need to be hooked up after placing them in the ground. It is more interesting to see what is in one of these storage tanks, so its great that they have to build it up while we keep the cameras rolling.

Below is a set of pictures from the stationary webcam for today’s progress. It should be finished tomorrow and I will do a drawing of the layers to point out various elements.

Sand used to level/flatten ground

Sand used to level/flatten ground

Foamboard floor and walls

Foamboard floor and walls

Spray foam to hold it together

Spray foam to hold it together

More walls/floors

More walls/floors

more foam

more foam

finished walls and floor

finshed walls and floor

Water tight liner

Water tight liner

Finished liner

Finished liner

Base layer of stones

Base layer of stones

Temperature sensor tubing

Temperature sensor tubing

More rocks and sand

More rocks and sand

6 Comments

Dick Roth says:

My wife and I are doing a similar thing in Utah. We are collecting heat all summer to heat the house and melt the snow on our driveway in the winter. We used 2 prefab concrete tanks, insulated with foam all around. We filled them with sand. I wanted to use another storage medium – oil, water, etc – but it was a retrofit and not practical. We are charging the storage for the first time as I write. We are also using 400 gallons of water as storage in the house. Keep in touch if you want to trade results.


kimquirk says:

Sounds great, Dick! Thanks for your note.

I asked around quite a bit about the medium – water, oil, some special chemical mix – and so far the answer has been that water is the best medium. The tank we just built has a lot of sand and some stones, but its the water in the tank that is the key to storing BTUs. I don’t have much background in this so I am interested in learning more and looking out for a better medium.

Does your tank just have sand? Or is it sand and water? What is the size of your prefab tanks. Maybe you can do your own comparison with your prefab tanks and your water tank. Are you heating these both with solar panels? What kind? I will be using 4 sets of Sunda evacuated tubes — Seido 5-16. Do you have any pictures?

Thanks,
Kim


Dick Roth says:

Kim –
Short explanation – I’m in the utility grade concentrated solar business in Hawaii. My wife is overseeing the Utah remodel. She has some pictures, it will take a while but I’ll get them to you. I don’t remember the size of the tanks, but I’ll find out. We are using evacuated tubes, but I don’t know what kind. I’ll find out.

Long explanation – Storage is one of the keys to utility sized CSP, so that got me started with the Utah project. I wish we had done this when we first started on the house 15 years ago because I would have put the tanks in an accessible place and filled them with water, as I agree that it is the best medium, except for some commercial grade media like thermal oil or salt.

We settled on sand as the best available medium, though our initial calculations tell us we probably won’t collect enough heat to carry us through a winter. Thus the indoor water tanks. Best to do this when you are building the house, rather than when remodeling. We had to bury the tanks under our steeply sloping driveway. The sand allowed us to put the tanks on an angle. We would have had to go way too deep to put level tanks full of water in, and then the issue of access for cleaning etc would have been a major challenge. So we settled for something we could use as a data gathering tool for the next guy.

If you want to, drop me an email at dickroth@gmail.com. I’ll answer you from a different address.

Dick


Mike Secules says:

Do you know what the thermal conductivity is of the spray-on foam you used in the storage tank?


kimquirk says:

We used 13″ of closed cell foam which should provide close to R100 insulation. Thanks for your comments.
Kim


louisville plumber says:

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