Trying to find what kind of insulation material and how much to use on diy hydronic hot water storage tank. Currently in formulation but guestimate is 5.5 ft dia by 5 ft high. Trying to get as much storage capacity that volume allows with internal tank insulator. Tank is to be from used 275 fuel oil drums in four sections to be bolted together and as yet undetermined liner material. Heat source is an EKO-40 now going into 3rd heating season. Have considered fan-fold insulation 1/4" thick multiple layers. I have no idea what Tarm uses but from cubic displacement vs finished size they must have a lot of insulation. Any suggestions? Thanks...Cave2k
Storaage tank insulator
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My sense is that insulation belongs on the outside of the tank. Three reasons:
1) Hot water and insulation don't work together well. Many insulation materials break down over time at the temperatures involved, and waterlogged insulation is not really insulation at all.
2) Insulation inside the tank takes away from the available water storage volume.
3) Effective insulation is mostly air. It takes more than 60 pounds of force to hold a cubic foot of air under the water.
I use a bunch of insulation types, but mostly fiberglass and polyiso board.
1) Hot water and insulation don't work together well. Many insulation materials break down over time at the temperatures involved, and waterlogged insulation is not really insulation at all.
2) Insulation inside the tank takes away from the available water storage volume.
3) Effective insulation is mostly air. It takes more than 60 pounds of force to hold a cubic foot of air under the water.
I use a bunch of insulation types, but mostly fiberglass and polyiso board.
Ok with the external. I can do that. I was just going by what I saw of the the Tarm kits that are way out of my range financially. How thick is the insulation that you use and what type of liner do you use? Thanks...Cave2k
Cave2k said:
No liner - I have an open-top stainless tank. I use all of the following in various places:
- Foamed EPDM (already glued to the tank exterior)
- Aluminum foil (radiant barrier) with air gap
- bubble wrap
- Aluminized bubble wrap (Reflctix?)
- Foil faced polyisocyanurate board, all thicknesses
- Rigid EPS (Blue/Pink board)
- Packing peanuts
- Unfaced Fiberglass
- Paraffin (on water, to reduce evaporative loss)
- EPDM sheet (on water, to reduce evaporative loss)
I have about 12" insulation on the sides and 18" on top.
Nofossl How much parrifin do you use in your tank? Mine is 7' in diam.and I plan on using the parrifin on the top
NHFarmer said:
I threw in a couple of pounds. I've never opened it to see how well it worked. I lost zero water in the first year, and about 1/2" in the second year.
Ok. Thanks Nofossil. Is that 18" just precautionary to avoid thermal loss or is it necessary to do the job? I have limited space and need as small but effective barrier I can latch on to. Thank...Cave2k
Cave2k said:
The more the better. Mine is outside, so any lost heat is gone for good. Inside, I'd probably use half as much.
Thanks Nofossil. That's a relief. Because it's going to be inside I had thought 2-4" on the sides and an inch with 3/4 plywwod on the bottom Then fiber glass batting if more was needed. Your earlier comments about evaporate containment with paraffin I found to be helpful as I was worrying about water evaporation and an auto filler. Since your tank is outside and your loss is so low I think I will work more on barrier containment than loss replacement. Hey it sounds good anyway. Thanks...Cave2k
Just one more comment on storage. Think a bit about safety - pets, kids, and yourself. Water at these temperatures is extremely dangerous. Make sure you have a strong cover that no one can climb on. Think about where water would flow if you had a containment failure.
Good luck....
Good luck....
My storage is a milk tank so it's partially insulated to start with.... I'm not going to insulate this year because I will need some heat in my boiler shed to keep pipes from freezing.. So I actually want the heatloss from the tank..... then, I can gauge how much I need to keep the shed above freezing and insulate accordingly.......
I'll have the tanks spray-foamed if I decide to do further insulating on it.... It's easy, very hi R value per inch, and is just plain cool stuff!
I'll have the tanks spray-foamed if I decide to do further insulating on it.... It's easy, very hi R value per inch, and is just plain cool stuff!
Styrofoam (polystyrene foam of whatever name brand) is great stuff and has very useful weight/load bearing properties but everything I have found in manufacturer's literature says its long term service temp limit is around 150 to 160F. I've seen it 'shrivel' a bit from heat radiated from a nearby woodstove (don't ask). I don't know what it would do at typical storage tank temps but it gives off a weird smell when it gets hot and man will it burst into flame form the merest spark when it's almost too hot to touch. Isocyanurate still seems the safest plastic insulator material from both temp and flammability perspective. Fiberglass or cellulose loose fill for the irregular spaces saves a lot of money. My system is going in the insulated basement under my house. Putting it outside suggests to me that you couldn't use too much of whatever insulation you use. More has just got to be better.
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