Storage Tank Insulation Feedback Please

stokes79 · Mar 20, 2009

Getting ready to insulate my 1000 gallon propane tank. Here are the options I have come up with from this bulletin board past threads and some hybrid ideas:

I will frame a box around three sides of the tank, it sits in the corner of my shop so two exterior walls the the floor slab will be the other sides
Then I will staple a radiant barrier foil to the inside of the studs and to the sheetrock on the exterior/existing walls I have a roll left from my staple up in floor heat I figure it can't hurt anything and will be one more layer to help block air movement

There is a contractor that does blown in cellulose insulation, this would seem to be the least labor intensive, fill the inside of the box with cellulose minus blocked out areas for access to openings and drain valves. Then put Batt insulation in box framing and skin with plywood

or

Get Batt insulation in rolls and spiral the tank, possibly use some kind of spray adhesive to stick batts to ends of propane tank, do a couple lavers then wrap with chicken wire to hold everything in place. then stuff all the voids in the box with batt insulation, definately more labor.

If I have "chases" to all openings....potential leak spots probably just boxed out areas around plugs and valves with a removable panel, also filled with insulation which I could simply pull out to get at fittings and sensors, same deal with the fill/drain, removable panel in plywood skin, boxed in then stuffed with batt insulation for remove on use or inspection

What are the pros and cons of the above options, I also have 2 in pink foam board I thought about putting against the walls of the box, they are leftover, I saw on here that they can't handle the heat so there would be cellulose or fiberglass in contact with the tank and the rigid foam would be the outer skin no contact with tank and probably 8 inches away at closest point

I would caulk all the seams on the outer skin of plywood, tape all the foil seams and try to make shell as air tight as possible

This is a decent project and insulation isn't cheap so I don't want to fail or have to do it again later so any advice is greatly appreciated

Laters

Nofossil · Mar 20, 2009

This is a great question and it would be a good one to get definitive cost / performance data on.

Heat is lost from a closed tank by four routes:

1) Conduction
2) Convection
3) Radiation
4) In-pipe thermosiphoning
5) Infiltration / exfiltration

Despite tons of time spent on research, I've never been able to find good data on how much loss you can expect for the radiation part of the heat loss.

There's almost certainly some benefit to building a radiant heat trap on or near the tank. That's an air gap of around 3/4" with shiny (low emissivity) surfaces on both sides of the gap. Aluminum foil is near perfect for this purpose, but I don't have any magic solution for installing it. I used spray adhesive and wrapped the tank with foil, then wrapped it with large-bubble bubble wrap, then another layer of foil. Over that I did a variety of things including foil-faced polyiso board, reflective bubble wrap, and fiberglass.

Fiberglass is nice in that you can easily remove and/or replace it if needed, and it will have no issues with heat.

If I were doing it (and I might be, again) I'd probably do the aluminum foil / bubble wrap thing as best as I could, then wrap with fiberglass, then wrap that with plastic film (like shrinkwrap) to create an airtight insulation envelope. I'd then blow in packing peanuts or cellulose to fill in all the corners of the framed-in enclosure.

I'd also glue foil-fased polyiso board to the concrete walls, and put a layer of foam board on the floor.

thecontrolguy · Mar 20, 2009

Hey Stokes;

I am facing the same issue of insulating my 1000gallon propane storage tank and had thought that the best insulation (for the issues raised by nofossil) would be to spray the entire tank with the spray-on expanding foam that sticks. It would negate convective losses against the tank and should reduce / stop radiation issues as well. I believe there is a picture somewhere on this forum of a 500 gallon (vertical mount) tank that was spray-foamed. (?) I am aware of rentable kits that come with what looks like small propane tanks to use so you can apply this yourself. My only concern is the long-term stability of the insulation at the higher temperatures that the tank would be running at. Good luck.

Nofossil · Mar 20, 2009

Spray foam is good, but very expensive per cubic foot. Because of the temperature differentials involved, you want a good deal of thickness. When I did my storage, I was looking for the best performance per dollar. Lots of 'scratch and dent' polyiso panels in mine.

Vtgent49 · Mar 20, 2009

A couple of odd thoughts:

Where is the heat lost to? If it goes into a basement below a house, I'd be less concerned than if truly lost.

Also, I'd run my system thru all it's paces before sealing up anything. Both because of leaks, but also because of redesign. e.g I'm about to repipe my wood heated DHW to change from preheating the DHW thru the boiler, to a new thermosiphon loop thru the DHW boiler coil. This will eliminate my side-arm which I love and which produces all we need, but should/could be more effective (or just be more clever/fun, lol).

Thermo siphon losses can be much bigger than expected.

Al

tom in maine · Mar 20, 2009

People get confused over radiant heat loss. If you have any thickness of either fiberglass or cellulose, there is no radiant heat flow through it.
If you envision a wood stove or the sun radiating heat, you can stop that warming effect with a sheet of aluminum foil, a piece of fiberglass or just about any
other form of insulation.
Foil and foil faced materials are not necessary to stop radiant heat loss off a tank.

Now, convection within the "fluffy" insulations will allow warmed air to flow through it.
My experience is that foam is the best bet, but if you have any enclosure that you can fill with insulation, cellulose is fine--until there is a leak,
but that will never happen--right?

All kidding aside, I would use cellulose if that is what you prefer, it will do a good job.
It is also a wonderful nesting material for critters, so seal the enclosure well, which you should be doing anyway.

BTW, I would have at least R20 over everything, if you can afford the cost and space.

Tom
www.americansolartechnics.com

Nofossil · Mar 20, 2009

Here's an experiment for you:

Sit in front of a blazing hot fire. Hold up a 1/2" thick fiberglass batt between your face and the fire, then do the same with a sheet of aluminum foil. Fiberglass will eventually stop radiant heat loss, but the radiant energy will be converted into heat at various depths into the insulation. The aluminum foil stops (and reflects, rather than absorbs) the radiant energy. The fiberglass will pass some of the energy, and be warmed by the rest. The aluminum foil will be cool.

What I'm still struggling with is just how important that is in terms of overall heat loss in this application.

stee6043 · Mar 20, 2009

Fiberglass is cheap and easy to work with. It was a no brianier for me. This photo is half way through my insulation process. I enclosed it with OSB after I had stuffed a total of eleven rolls of R30 in.....

2.beans · Mar 20, 2009

i built a box out of 2 inch foilback insulation then filled the inside with pink stuff. seems to work good so far.

foxt · Mar 20, 2009

I insulated my new GARN install last fall with about 15" of pink stuff over the top, 5.5" on one side and the back, 3" of pink stuff on the front, and 4-5" of high density spray foam on the fourth side that also serves as the exterior wall of the building. Stuffed any other spaces with more pink stuff. Then I spent the winter chasing standby losses. I believe that fiberglass gets less effective at higher temps, and my understanding is that rock wool either does not, or is affected less. So now I am wondering if I should have used rock wool instead of fiberglass. Something to consider if you already haven't done so ...

VtRv · Mar 20, 2009

I debated over this with my 500 gallon LP tank. I was all set to have it spray foamed until I spoke with the contractor who said he wasn't sure he could get the back of the tank very well as it was already set in place in my basement about 8" from the concrete wall.

I ended up putting foil back 1" foam board against the concrete wall an under the tank. I then wrapped the tank in fiberglass with the barrier out and used duck tape to keep it all together. I then built a box around the three sides and put the 1" foil face foam on the inside of the box against the fiberglass, stuffing loose batts of fiberglass in any crevices I could find. I put more fiberglass on top and my plan is to seal the top as well with plywood.

I took home a Thermal Imager that I have access to and found that heat was leaking around the joints where the box comes into contact with the concrete so I spray foamed all of them and that seemed to stop the heat loss.

Using the Thermal Imager again I think I have minimal heat loss.

If I were to do it again I think I would build a box and use the foam board but I would spray in cellulose. My concern at the time was condensation with the cellulose. It wasn't an issue over the winter and I'll watch it over the summer and see are any issues with it.

I think renting a blower and using cellulose would be the best bang for the buck.

I'm now trying to find a cost effective way to insulate the pipes in and out.

tom in maine · Mar 20, 2009

The radiant energy will not pass through fiberglass that is 6" or thicker. Period. There might be some convection, but this should be enclosed somehow.
I do not like fiberglass, do not use it, but it is cheap and people like it for some reason. It is relatively fireproof.
As crappy an insulation as fiberglass is, it will stop any radiant heat movement. If convection occurs as a byproduct, an enclosure or plastic wrap will mitigate that.

Aluminum foil will reflect radiant heat but will also conduct heat. That sheet of foil will heat up in due time.
NOTHING beats straight ahead R value. We only used foil before we had good insulation alternatives. The foil faced products that are out there now (bubble wraps and thin flexible foams and P2000) all rely on people not understanding how insulation works.

As someone else said, if money is an issue, use cellulose, it will do the job better than fiberglass and is not itchy and will suppress any convection much better than fiberglass.

Me, I'm sticking with foam. haha.

pybyr · Mar 20, 2009

Tom in Maine said:
All kidding aside, I would use cellulose if that is what you prefer, it will do a good job.
It is also a wonderful nesting material for critters, so seal the enclosure well, which you should be doing anyway.

Any of the modern cellulose insulations are treated with borate compounds for the dual purpose of fire retardancy and critter-repelling. I've seen old houses where rodents have stripped out the fiberglass for nesting material (remarkably, it does not seem to make them itch- they seem to favor it), but I've never seen rodents make headway into dense-packed fire-retardant cellulose. The cellulose, if installed to proper density, will also not allow the convective air currents that are common in fiberglass.

tom in maine · Mar 21, 2009

I agree about using dense pack cellulose. I have been into houses with little burrows all through the cellulose. They know what's good.
It seems prudent to at least to enclose it with plastic if not wood.
It probably seems very cozy.
The last house I was into that had high density cellulose in it was also full of burrows and mouse urine. Was lovely.

This would not deter me from using it, just be sure about tightness.

8nrider · Mar 21, 2009

had a conversation this afternoon with a man that left his girfriend three months ago. homeless agian. set up a dome tent inside a dome tent . small cook stove for heat. below zero nights he never was below 55 inside.

stokes79 · Mar 21, 2009

Thanks for the comments, just wanted to add it is in my shop which is located under the living space of my house, so the current uninsulated tank is just a huge radiator and yes the heat isn't lost just not used as intended.
My main reason for insulating the tank is to reduce my standby losses, I have spring flow check valves on my supply return at storage so that should slow down thermosiphon, all pipes are double insulated with black foam. I just really don't want my shop 80 degrees, ever. and I hope to use this boiler setup year round to supply hot water.
thanks
casey

DenaliChuck · Mar 22, 2009

Anyone play with blown in fiberglass? Local carp crews here like it and it seems like it would respond better to a future leak better than chopped cellulose...

Piker · Mar 30, 2009

Alright... this week is the week. Storage is getting installed come heck or high water. I've got the used propane tanks cleaned and prepped to weld some black iron pipe for supply and return lines, and I have an idea to make a 3' long well out of 1/2" copper to place a 4 sensor array in to measure temperature. I am going to pipe the tanks in parallel, keeping the piping all exactly the same length from the "T's," so I am only going to put sensors in one tank.

Now, insulation. Sitting here going over the time and expense in building a polyiso box with blow in cellulose insulation, I think I can almost buy one of those spray foam kits for the same price. I figure I need 6" of foam on the tanks... which encompass about 96 sq feet each. Since the tanks will be setting side by side, some of that square footage will overlap in the valley between the tanks.

I was thinking of this product: Foam It Green

Have you seen any other products out there that might be less expensive? I don't necessarily need to "foam it green."

Man, it's pricey, but no screwing around. The area that I will be placing the tanks is in a 6' tall crawlspace under the kitchen. It has a dirt floor, fairly damp, with lots of scary bugs and such. Probably mice too. I am thinking not only is foam not that much more money, but probably safer for the area that I want to install in. What do you guys think?

I would put a form around the sensor array and the fittings so as to keep foam off of them, and allow access to the fittings them selves. I can fill the holes around the fittings with fiberglass after everything is hooked up.

Let me know what you guys think.

cheers

SteveGH · Mar 30, 2009

DenaliChuck said:
Anyone play with blown in fiberglass? Local carp crews here like it and it seems like it would respond better to a future leak better than chopped cellulose...

Don't know if we're talking same product but that's what I had put in when we built our home 9yrs ago. It is shredded fiberglass coated with a dry adhesive powder. On application the sprayer has a fine mist of water that activates the adhesive. It was then shaved off even with the studs, sucked up with a big vac back to the blower and recycled. I wish I could remember the specs, or name for that matter. Insulating value, non-settling, ability to work around wiring and plumbing avoided the normal compression of bats were all positives in my book. The best is no itching.

Floydian · Mar 30, 2009

Hey Piker-

Have you gotten prices from local spray foam installers? In my area I can get it for $1.25 a board foot. ($15 a cubic foot)
Thats for closed cell polyurethane. 2 pound density I think. Worth checking out. Might save you some bucks and save you from
the application.

Noah

DenaliChuck · Mar 31, 2009

whtmtnbiker said:
DenaliChuck said:

Anyone play with blown in fiberglass? Local carp crews here like it and it seems like it would respond better to a future leak better than chopped cellulose...

Click to expand...

Don't know if we're talking same product but that's what I had put in when we built our home 9yrs ago. It is shredded fiberglass coated with a dry adhesive powder. On application the sprayer has a fine mist of water that activates the adhesive. It was then shaved off even with the studs, sucked up with a big vac back to the blower and recycled. I wish I could remember the specs, or name for that matter. Insulating value, non-settling, ability to work around wiring and plumbing avoided the normal compression of bats were all positives in my book. The best is no itching.

I don't know...I'll check into it. Did it look like good DIY material?

DaveBP · Mar 31, 2009

Just a caveat for those considering spray foam over their tanks. I've seen a number of instances of ants and rodents burrowing into rigid foam. Whole colony of carpenter ants swiss-cheesed some blue and pink styrofoam I had stacked on the ground a few years ago.

I still think sprayed-on foam would be one of the ultimate choices for effectiveness and simplicity. But I would think about painting a few coats of epoxy paint on there for weather protection as well as discouraging vermin from taking advantage of the biggest incubator in town. Maybe that aluminized asphalt roof paint if it's compatible with the urethane?

SteveGH · Apr 1, 2009

DenaliChuck said:
I don't know...I'll check into it. Did it look like good DIY material?

Don't see why not as long as you had the equipment. The product came in bags, emptied into a big hopper in a truck outside that had the blower and vac system. It was blown through 4" line (ok that's trusting the 10yr old memory banks). Excess/shaved material was sucked back to the truck and recycled.

DenaliChuck · Apr 1, 2009

The product these guys use looks just like chopped cellulose, except that it is fiberglass. It doesn't require wetting, and wouldn't stick in between studs.

Sounds good to me in that it would be easy to install, inexpensive, easier to remove than spray foam, and is more resistant to moisture in case (when) a small leak develops.

I'll likely be ready to insulate in 6-weeks (just in time for summer!) and I'll post how it goes.

DC

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