Where to buy 2" polyisocyanurate??

[jondecker76]

I'm trying to finish my Plywood/ EDPM lined solar water storage tank, but I can't find anyone around me (in North East Ohio) that carries polyiso. Of the 10+ places I've called today (including Lowes and Home Depot), only one place heard of Polyisocyanurate insulation, and they could only get it in 1/2" sheets for almost $20 per 4'x8' panel.

Does anyone have suggestions on where to look to find this stuff?? At least in 1" thickness anyways. I can't believe I'm having such a hard time finding something so simple!

[zap]

The last time I bought some was at Home Depot.

I'd try lumber yards, insulation contractors, and HVAC contractors around here use it often.

[ghurd]

Lowes (44484) had Celotex Tuff-R (with aluminum coating) in 1/2" and 1".

Not cheap, but 1" was only a bit more than 1/2".

They may have changed the name to Celotex GA3000.  Call and ask for that or Tuff-R.

G-

[dnix71]

A commercial roofing supply house is your best bet.

http://cgi.ebay.com/4x8x3-4x4x3-POLYISO-INSULATION_W0QQitemZ130309567971QQihZ003QQcategoryZ63894QQss
PageNameZWDVWQQrdZ1QQcmdZViewItem

These people have trailer loads in Illinois, 3 inches thick. It doesn't seem to be a common retail item. You can't exactly mail this stuff, and it takes a lot of space without weighing much, so it is much more economical to ship by rail in large quantities.

Any decent sized town on a rail line would have lower prices.

[David HK]

It's also marketed as Kooltherm.

By the way, its excellent stuff. It puts up with 99.1 Centigrade hotwater pipes in my solar hot water heater. No sign of damage or deterioration.

David HK

[GaryGary]

Hi,

Some of the places that have the polyiso don't know it by that name.  It might be worthwhile just going to the yard, and looking at the sheets -- it will say Polyisocyanurate somewhere on the sheet.

Even in our little town, I can get 1/2, 1, 1.5 and 2 inch polyiso in the Atlas R-Board brand.  Firestone also makes it.  Its $32 per sheet for the 2 inch here.

I guess that if you just can't get it in thicker sheet, there are some other alternatives:

• use one sheet of the polyiso you can get, and then outside of that use the extruded polystyrene foam board (the pink or blue) stuff.  Idea being that the temp will have dropped enough by the time you get through the thin polyiso that the polystyrene will be up to it.  
  
• build a shell around the tank with light material and stuff the space between the tank and new outer shell with fiberglass.  Just be sure to seal up any places that would allow airflow, as the fiberglass is very pervious to air flow.  Cellulose would probably also be OK.  
  
  

You still need the rigid foam board under the tank.

What is the max temperature you expect the water in the tank to get up to?

Gary

[jondecker76]

Gary - I'm building similar to the $1000 solar water heater setup on builditsolar.com. My tank is 4'x4'x4' and should hold about 350 gallons of water after accounting for the insulation and heat exchange coil. Since my tank seemed a bit taller than the on on your website, I also added a 3rd perimeter of lapped 2x4's about half way up the tank. Also, I built a base for it out of treate 4x4 lumber, which has 4 stringers running along the bottom to carry the weight. I was also going to shoot for 130-140 degrees tank temperature, to thwart off bacteria such as legionella.

I'm going to have to go look around for the insulation, as I'm still have no luck at all. I called corporate Lowes last night and gave them the part number of some 1" board that I found on their website. They said it wasn't carried anywhere in my district, and couldn't even tell me the closest lowes store to me that stocked it. You are probably correct in that most people will probably know it as a brand name of some sort.

One other change I am making for my tank is that I'm going to use bulkhead fittings and pipe in through the liner. I will just have to make sure that I get it sealed well.

I'll be sure to post pictures of the tank once its finished. (all that remains is getting the insulation and EDPM liner)

[GaryGary]

Hi,

The extra frame is not a bad idea -- there is a lot of water pressure on the tank sides.  Be careful to make sure that on the perimeter frame corners that the east-west frame member has a good strong shear connection to the north-south frame member -- a full glued lap joint + screws, or flat metal splice plates.

Since you are keeping the temps fairly low, you might be able to just insulate on the outside of the plywood tank walls.  The plywood wall has about an R 0.75, so the temperature will drop across it some -- this might be enough to get it to where the extruded polystyrene insulation would be OK.  But, the bad things about this are that 1) insulation on the inside of the plywood will be more effective and easier since there will not be any thermal bridges from the perimeter frames, and 2) if the temp ever does get high in the tank, then you could damage the polystyrene.  

Better to find the polyiso if you can.  If you have some independent lumber yards in the area, you might try them.  Both of the two places that carry polyiso in Bozeman are independents -- our HD and Lowes don't carry it.

If you can find the 2 inch polyiso, I would put 2 inches inside as long at that leaves room for the pipe coil heat exchanger you are using -- this gives you close to R14 with no thermal bridging.

Please let us know how it comes out -- if you post it in the diaries section, maybe you can drop me an email when you do.

Gary

[jondecker76]

Ok, I finally sourced some 2" polyiso... I'm going to pick it up on friday, but I'm driving about an hour to get it (could not find anyone local.)  After taxes it was $91.91 for 3 sheets - I'm sure I could have done a bit better on price, but after fighting for a full week just to find someone that could get it, I figured I'd just take what I could get.

Anyways, thanks for the help

[mbeland]

We have no problem finding polyiso here in New brunswick Canada. The product I used for my house was known as Rx from what I remember.

It seems like the insulation is the most expensive item in those tanks. Has anyone ever thought of using just a minimal (maybe 1 inch) thickness of polyisocyanurate under the EDPM liner and using cellulose loose fill insulation which I assume would be much cheaper than rigid boards? The way I thought one could do that without having the thermal bridges would be to build the tank out of 2 layers of 2" x 3" instead of one layer of 2" x 4" just like in superinsulated houses. The 2 layers of 2 x 3 would be perpendicular and could thus be made pretty rock solid. That could be one layer of 2 x 4 and one of 2 x 3.

Martin