Insulation Question for Water Storage

[sdrobertson]

I'm placing 4-500 gallon propane tanks standing on end in my polebarn. The total height will be 12 ft to the bottom of the trusses. The space is 8ft square and I will be standing them as tightly as I can get them. My original thought on insulation is to fill the cavity with fiberglass insulation. I now wondering if it would be better to fill it with "loose fill" or "blown" insulation as this appears to have more "R" value per inch as fiberglass. Once I get the boiler fired and leak check everything, I should not have to every open up the walls and get to the tanks, so my question is which would be better - fiberglass batts or loose fill? If loose filled, how much should I expect it to settle so I can figure how much to add to the top. Attached is a photo of the tank storage area.

 

[Sizzler]

Not sure what is the better insulation but I have temporarily surrounded my tank with R-19 bottom and sides and R-38 fiberglass on the top. Been heating DHW the past two days and judging from my daily heat losses i will be adding more. Perhaps twice this amount. I still need to insulate the water lines as well.

 

[Nofossil]

Hard to get too much insulation. Based on my experience, you'll want to make sure the mice are kept out. I had some chew a tunnel through 6" of pink board to get to the inside, where they made condominiums in the fiberglass.

 

[Sizzler]

Good advice.. I'll be adding a bucket of Ropax along with the added insulation.

 

[pybyr]

in prior projects, I researched the heck out of pros and cons of various types of insulation. dense pack cellulose holds its R-value exceptionally well with low outdoor temps, fills voids well, and repels rodents (with its borate treatment) I'd say, fill the whole area around your tanks with dense-packed cellulose using a rented insulation blower.

Trevor

 

[sdrobertson]

Thank you for the replies. Looking online I see that there is alot of different types of "blown insulation" so I'll be checking locally to see what available.

 

[sdrobertson]

Checked with a local supplier. He's recommending to use "sheet" styrofoam to line the walls and then to pour miniature styrophone balls around the tanks because the balls will hold up better if there is any moisture in the tank area. He states that the sheets have more insulating value than the loose filled balls as it is more dense. The "R" value is supposed to be between 3 to 4 per inch.

 

[pybyr]

Styrofoam- not so sure! I'd be concerned about whether regular-grade styrofoam can handle the sustained temperatures you'll get with a heat storage; I'd also be a bit concerned about its rather high flammability- especially given that at it's elevated temperature in this application, it'd be that much closer to its ignition point if anything did cast a spark in it. R-value-wise, dense-pack cellulose will do as well or better than R3 to 4 per inch, it isn't flammable (due to the borate treatment it contains) and it keeps bugs and vermin out (again due to the borate). And it's basically a low-net-energy recycled product compared to any of the plastic insulations. I have no commercial interest in the stuff, I'm just a very happy user of it in several applications.

 

[sfriedri]

Has anyone looked into spray polyurethane foam as an insulation method for storage tanks? It is getting to be more common in residential construction. The closed cell types have an R value of 5 to 7 per inch. However, I'm not sure of how it would handle 200+ deg F temps, or how much it would cost.

 

[sdrobertson]

I haven't priced spray foam, but I do know that it is more expensive than other types and I'm cheap and I like doing it myself. I think I'll take the advise here and go with the dense-pack cellulose, but the only thing I have to research more is that the only technical data I could find is from Regal Industries ((broken link removed to http://www.regalind.com/technical.htm)) and all the products state not to use if temps go over 180 degrees. I'm awaiting answers from them as to if there is a dense-pack cellulose product that will take the heat around 200 degrees.

 

[WoodNotOil]

I haven't priced spray foam, but I do know that it is more expensive than other types and I'm cheap and I like doing it myself. I think I'll take the advise here and go with the dense-pack cellulose, but the only thing I have to research more is that the only technical data I could find is from Regal Industries ((broken link removed to http://www.regalind.com/technical.htm)) and all the products state not to use if temps go over 180 degrees. I'm awaiting answers from them as to if there is a dense-pack cellulose product that will take the heat around 200 degrees.

You can always wrap the tanks with some kind of insualtion that can take high heat, like polyiso, for several inches and then use the cellulose to fill the rest of the cavity. I would think that only the insulation closest to the tank will really be exposed to extremely high temp. Here is a link http://www.engineeringtoolbox.com/insulation-temperatures-d_922.html to more information on the high temp rating of various types of insulation. I have also added the link to my tank design page on my website in my signature for future reference.

 

[jebatty]

I think you will want some access-ability: to drain, fill, and the vents for the tanks. When you stand them on end, do you have a vent on the top of each tank to get rid of air?

 

[Miner3]

I'm new to the forum but have had a Tarm Solo 60 for 2 years with 1000 gal. pressurized storage. I located the unit in my shed with 2- 500gal tanks on end surrounded with loose fill cellulose from the big box store. Settled a bit the first few months but topped off with a 2-3 additional bags of cellulose. I also lined the enclosure with 3/4" foil faced foam and used spray foam over the few inches of cellulose on top of the tanks. The vent on top of each tank extends through the insulation.

 

[sdrobertson]

Welcome to the forum Mark. How high do you run the tanks up to? Your set up sounds like exactly like I thinking about.

 

[Miner3]

The tank temperature usually runs at 185F but I have hit 190F when the system is running full out. I have a trerice thermometer near the top of one tank and another mid way up the other tank. They run within 5 deg of ea other when the boiler in charging. Because the tanks are on end in the shed I noticed the frost on the metal roof melt directly over the tanks. Thats when I added the spray foam cap over the cellulose on the top to minimize loss.

 

[sdrobertson]

Over the weekend I attended a Energy Conference and there was a salesman displaying the "newest and greatest" insulation. The product was basically 1/2 inch Styrofoam with a reflective foil sheet covering it. The display had a 1 foot square box covering a 100 watt light bulb. Metal probe thermometer reading 140 degrees inside and the outside being room temp. This got me thinking what if I placed the tanks tightly together and then built a box out of 4x8 sheets of foil backed insulation and then fill the space between the insulated box and the outside walls with dense pack cellulose and then it wouldn't matter if the cellulose can take up to 200 degree temps. Another plus would be that if I ever do have to get to the tanks, I could run one section of the 4x8 sheets all the way to one wall and would only have to remove a 4x8 space of cellulose to get in. I'll have air spaces around the tanks as they are round and the "box" will be square, but with taped seams, and cellulose surrounding the air space I shouldn't get any air movement. Please, any thoughts to help me figure the best way to do this.....

 

[Nofossil]

Maybe someone at NASA knows the answer, but I haven't been able to get anywhere figuring this out. There are several ways that heat can be lost from a storage tank of the type we're concerned with:

1) Conduction. That's want U-value and R-value measure.
2) Radiation. That's what an air gap with reflective foil is goos at stopping.
3) Convection. That's when warm air or water is able to move up and/or out, being replaced with cooler air/water.
4) Evaporation.

R-value doesn't address the last three. To me, there are two basic questions:

1) If you have a limited amount of space for insulation, what material or combination of materials will provide the lowest total heat loss?

2) Same question, if your budget is limited.

 

[sdrobertson]

I called the manufacturer today and asked them about direct contact with 200 degree temps. He stated that the 180 degree rating on the bags is to insure that when it is installed, the cellulose is kept a minimum of 3 inches away from light fixtures and chimneys. Prolong exposures to 200 degrees will have no affects on the quality, nor will it cause added settling of the cellulose. I guess I have finally decided on how I will insulate - one more decision down!!

 

[pybyr]

good to know, and thanks for passing the information back. one thing, when you go to install the cellulose, even though it'd seem like you could open the "bales" and shred it up and toss it in by hand- rent a blower instead (tool rental places seem to have them)-- the blower shreds the stuff and mixes it with air, so that it's uniform- otherwise it goes in in mats and chunks, which (A) uses more material; and (B) has a lower R-value.

 

[Yates]

How are you insulating underneath the propane tanks with all the weight. I'm trying to figure out a good design for a shed to store 2 -500 propane tanks, EKO60, and 8 cords of wood. The insulation space is the main question on the side if you could have any width of side insulation and how to insulate the bottom. The shed will have a concrete floor. Any help would be appreciated.

 

[sdrobertson]

I'm standing the tanks on end with semi truck rims for a base welded on the ends. I built the "box" to be a little over two ft larger than the tanks so I'll have more than 12" of insulation on the sides. The bottom sits on the rims and I did not insulate the floor but I will fill the inside of the rims with insulation so I'm not sure how much I'll lose but I think it will be minimal. The problem I see is that the heat will want to travel through the rims to the concrete but with all that weight, I want a good base.

 

[pybyr]

doesn't seem like you should lose all that much heat, relatively speaking, downward. If you wanted to, you could cut circles of polyiso foam board the inside diameter of the truck rims and set the tank/ bases down over that- at that point, your only real loss would be conduction via the rims, which should be minimal-- and I agree, with the weight that you're dealing with, you want sturdy and stable!