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david congour Posted: Jul 16, 2007 01:27 PM	Suitability of SPF for hot water tank insulation. I manufacture hot water storage tanks (approx 400 g, up to 180 deg F) for storing solar heat for later circulatin thru radiant floor systems. I presently use a rubber bladder that contains the water and protects polyisocyanurate insulation boards that provide the insulation. I want to replace the polyiso board insulation with SPF. I then want to spray the surface of the SPF with a flexible, high temp "marine type" sealant. Using this method, I hope to contain any possible future micro leaks leaks in the bladder from ruining the SPF (by soaking with hot water). Will SPF hold up for, say, 20 years under this scenario? Can you recommend any sources for sealants that are compatable with SPF? Thanks
mason Posted: Jul 16, 2007 02:04 PM	This is an application that has been successfully used in the Caribbean since the late 70s. Yes, the foam will hold up well. If the tanks are on the roof or outside, the foam should be a minimum 2.5 lb density product and be protected with a suitable UV resistant elastomeric coating (like the types used for roofing applications). The tanks would need to be recoated every 10 to 15 years. There is a high side temperature limitation on foam used on hot water tanks, it should be kept below 200 degrees F or the foam may discolor and even char against the hot surface causing delamination. But at 185 degrees F and below, you should have no problem.
david congour Posted: Jul 16, 2007 02:32 PM	Thanks for your quick response; it's good news to me!
david congour Posted: Jul 16, 2007 02:49 PM	A followup question if I may... Are you aware of an appropriate elastomeric coating type for my application, or recommend somebody that would know? Most of the products I see in my research are for roof covering, and are good for high heat, but maybe not specified for continuous underwater use. Ideally, I'd like a coating capable of being submerged in the hot water over a period of years, even without the bladder present. This would be in case the bladder developed a small pinhole leak (possibly even during final assembly of the tank). This would, in effect, give me two separate containment mechanisms to protect against leaks. Once again, thanks in advance for your help!
mason Posted: Jul 17, 2007 06:52 PM	Polyurea coatings have very good waterproofing qualities, adhere well to sprayfoam and have a fairly wide temperature range. Chlorine may be a problem with some systems, check with the manufacturer for their recommendations.

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Comments

david congour

Posted: Jul 16, 2007 01:27 PM

Suitability of SPF for hot water tank insulation.

I manufacture hot water storage tanks (approx 400 g, up to 180 deg F) for storing solar heat for later circulatin thru radiant floor systems. I presently use a rubber bladder that contains the water and protects polyisocyanurate insulation boards that provide the insulation.

I want to replace the polyiso board insulation with SPF. I then want to spray the surface of the SPF with a flexible, high temp "marine type" sealant. Using this method, I hope to contain any possible future micro leaks leaks in the bladder from ruining the SPF (by soaking with hot water).

Will SPF hold up for, say, 20 years under this scenario? Can you recommend any sources for sealants that are compatable with SPF?

Thanks

mason

Posted: Jul 16, 2007 02:04 PM

This is an application that has been successfully used in the Caribbean since the late 70s. Yes, the foam will hold up well. If the tanks are on the roof or outside, the foam should be a minimum 2.5 lb density product and be protected with a suitable UV resistant elastomeric coating (like the types used for roofing applications). The tanks would need to be recoated every 10 to 15 years. There is a high side temperature limitation on foam used on hot water tanks, it should be kept below 200 degrees F or the foam may discolor and even char against the hot surface causing delamination. But at 185 degrees F and below, you should have no problem.

david congour

Posted: Jul 16, 2007 02:32 PM

Thanks for your quick response; it's good news to me!

david congour

Posted: Jul 16, 2007 02:49 PM

A followup question if I may...

Are you aware of an appropriate elastomeric coating type for my application, or recommend somebody that would know? Most of the products I see in my research are for roof covering, and are good for high heat, but maybe not specified for continuous underwater use.

Ideally, I'd like a coating capable of being submerged in the hot water over a period of years, even without the bladder present. This would be in case the bladder developed a small pinhole leak (possibly even during final assembly of the tank). This would, in effect, give me two separate containment mechanisms to protect against leaks.

Once again, thanks in advance for your help!

mason

Posted: Jul 17, 2007 06:52 PM

Polyurea coatings have very good waterproofing qualities, adhere well to sprayfoam and have a fairly wide temperature range. Chlorine may be a problem with some systems, check with the manufacturer for their recommendations.

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