Advice on thermal storage tank (1040 gallon)

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.

DSSA

Member
Nov 29, 2017
39
Rockhill Twp. , PA
I’ve procured a 1040 gallon tank to use for thermal storage.

I have it unloaded from the trailer in the garage it will live in, but before getting it upright and moving it, I wanted to see if anyone has advice that I should know/consider with insulation/mounting.

I had planned on spray-foaming the bottom of the tank before standing it upright, but also didn’t know if it was really a requirement or highly suggested to place something between the skirt of the tank and the concrete floor as well.

I’m just trying to have everything planned/thought out before getting it upright and into position—she’s a bit heavy/ungainly (2400lbs.) so I’d like to only do it once.


Thanks for any advice/suggestions on mounting/insulation/anything else I’m not thinking of!
 

Attachments

  • [Hearth.com] Advice on thermal storage tank (1040 gallon)
    IMG_9228.webp
    695.7 KB · Views: 8
  • [Hearth.com] Advice on thermal storage tank (1040 gallon)
    IMG_9227.webp
    836.2 KB · Views: 7
  • [Hearth.com] Advice on thermal storage tank (1040 gallon)
    IMG_9292.webp
    312.5 KB · Views: 7
  • [Hearth.com] Advice on thermal storage tank (1040 gallon)
    IMG_9293.webp
    243.3 KB · Views: 7
Additional notes/information:

The tank will be housed in an insulated garage which gets to freezing temps. We've had colder nights here lately 15-18 degrees, and the garage, without being heated typically stays above 35 degrees minimum. I'm not too worried about it freezing while not being used, noting the above and it being 1000+ gallons, but would like to string out batch burning as much that can be reasonable, and don't want to cook myself out in the summer when we use it to heat DHW. I've looked at several options, but am unsure what R value I should be shooting for.

If I wasn't trying to conserve space, I'd just build walls around it and insulate it with foam boards/fiberglass/etc., but she's a big girl as it is, and I'm already losing a lot of space in that building for this system. I'm trying to find the best ROI tipping-point here.
 
We use this type of tanks a lot.
We spray foam them with a minimum of 2" of closed cell foam.

We do not put a thermal break between tank and concrete floor.
It is a good idea tough.
Maybe a high-density plastic sheet.

I recommend you use a 2-port piping setup, instead of a 4 port.
Less disturbance of the thermal stratification
It looks like you have at least one 6" port.
Can't see the other ports

[Hearth.com] Advice on thermal storage tank (1040 gallon)
 
We use this type of tanks a lot.
We spray foam them with a minimum of 2" of closed cell foam.

We do not put a thermal break between tank and concrete floor.
It is a good idea tough.
Maybe a high-density plastic sheet.

I recommend you use a 2-port piping setup, instead of a 4 port.
Less disturbance of the thermal stratification
It looks like you have at least one 6" port.
Can't see the other ports

View attachment 344061
Two ports on opposing sides (one high, one low).

I had planned on doing just 2-ports as pictured.

Thanks for the insulation and thermal break info!

Much appreciated!
 
Spray foam is a great option but I ended up using Rockwool batts and regular fiberglass insulation packed into an enclosure around the tanks (minimum R15). You will save some space with spray foam but probably not a lot. I have 4 tanks in series with angle iron legs hooked up in a 2-port configuration. The legs have a flat base plate which sits on a layer of 1/2" OSB and 1" 25PSI EPS foam. I'll include a thermal image showing the temperature gradient from the tank to the concrete floor. With one large tank like yours I'm not sure if 25PSI foam would be adequate. Probably OK with a thicker layer of OSB or some LVLs laid flat to spread the load.

[Hearth.com] Advice on thermal storage tank (1040 gallon)

In a 35F garage the heat loss will be significant without good insulation. You might consider spray foam plus 3" of additional insulation, otherwise you may be unintentionally heating your garage. The hottest water will be at the top so adding more insulation there will be good.

If the system is not running, how will you make sure the rest of the plumbing around the tanks does not ever freeze?
 
Spray foam is a great option but I ended up using Rockwool batts and regular fiberglass insulation packed into an enclosure around the tanks (minimum R15). You will save some space with spray foam but probably not a lot. I have 4 tanks in series with angle iron legs hooked up in a 2-port configuration. The legs have a flat base plate which sits on a layer of 1/2" OSB and 1" 25PSI EPS foam. I'll include a thermal image showing the temperature gradient from the tank to the concrete floor. With one large tank like yours I'm not sure if 25PSI foam would be adequate. Probably OK with a thicker layer of OSB or some LVLs laid flat to spread the load.

View attachment 344071
In a 35F garage the heat loss will be significant without good insulation. You might consider spray foam plus 3" of additional insulation, otherwise you may be unintentionally heating your garage. The hottest water will be at the top so adding more insulation there will be good.

If the system is not running, how will you make sure the rest of the plumbing around the tanks does not ever freeze?
I'm starting to look at spray-foaming the bottom and top, then have been looking at 1/4" Aluminum/PE thermal barrier to wrap it in.

As for freezing, it's not a concern. The system will be tied into the oil boiler in the house, which I can circulate in worst case scenario, and the garage it's housed in has an oil fired furnace that I can run to keep it from freezing if the need arises.

I appreciate your data input, and response. Thank you!
 
Last edited: