Pipe insulation

Paul Pollets

I'd be a little concerned with running 180 degree water through Pex. For water temps higher than 165, we run copper, or Pex-Al-Pex.

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Mark_46

Insulating PEX

I'm curious to know what the brain trust here on the Wall can tell me about insulating PEX tubing?

I have 3/4" Uponor supply and return PEX tubing running from the basement to the attic (where the air handler is) via a stud bay. The supply water temp (for now) will be 180. Is there a preferred insulation type and thickness? Will a 'Home Depot' variety suffice? Each run (supply and return) is 50 feet, 100 total.

I unserstand Armaflex is typically for retarding heat gain and controlling condensation drip from cold-water plumbing, chilled-water or refrigeration lines. But it also reduces heat flow for hot water plumbing and liquid-heating. So would Armaflex be the ideal material?

Brad White_9

I use Armaflex

but getting a tight fit may be an issue... I use the non-split type where I can, but that takes planning... too much for me. So if I split it, (by hand, I bought the unsplit solid tube type), I seal it with the Armaflex tape over their "contact cement" adhesive.

Mark_46

Hi Brad

How's things?

Ya, the non-split type won't be an option for me. I dont want to get into draining the system, cutting each tube at one end or the other to slide the pieces on. Then re-expanding the PEX to reconnect and refilling the system, etc. So for me, split-type it is.

This is going to be tricky install anyway. The tubing is exposed in basement and attic...piece of cake. But in the stud bay I believe I can slide the pieces on one after the other using a 'train' method. I plan to loosely tape the the foam every 3-4 inches (avoiding compression of the foam) so it is a little more supportive for sliding up the length of tubing while pushing the piece in front of it. I only need to go about 8-9 feet up from the basement and 8-9 feet down from the attic to meet in the middle. I guess this amounts to 2 pieces each way or so.

Not knowing too much about Armaflex's products, I take it you dont have a preference to thickness or type? (if there are different types). I guess it is wise to install the thickest I can fit?

Brad White_9

Yo Mark!

Reminds me: Ever hear of the dyslexic Rabbi? He says, "Yo Yo Yo!"

OK, I am done now...

Anyway, yes, split Armaflex is the way to go. The self-adhesive stuff (peel and stick) is just OK, you have to pinch it like a pie crust to seal it, but I over-tape it with Armaflex tape. It is not made by Armstrong as it once was, it is made by a spin-off company "Armacell", in NC I believe.

The most common Armaflex I find is 3/4" thickness. Not sure about tube sizes beyond nominal copper and steel sizes, so you have to find the best OD fit that you can. The performance is thermally about the same as fiberglass, no real thickness benefit but it is more flexible (and hey, so is PEX!)

When I did a radiant floor at a performing arts center here in MA, I had abundant parallell home-runs and used 3/4" Armaflex for those so as not to overheat that interior area. The IR gun measures the difference, so even under a slab it works.

Hope this helps-

Brad

Unknown

Size

3/4 HePex is 7/8OD the same as copper tube. A snug fit with Armaflex is very easy to attain.

Seal the split using the preadhesive peel and stick stuff. A piece of tape every so often as you descibe will allow too much heat to escape.

It will not be a tough install. Most wholesalers carry this product in 1/2 wall thickness. You will be looking for 7/8ID Armaflex with 1/2 wall, peel and stick.

Best of luck to you!

Mark_46

Paul

Interesting question. I double checked with Uponor/Wirsbo. According to their tech support, in this temp range their PEX is rated as per below:

180 deg @ 100 PSI

200 deg @ 80 PSI

I think the limitations are also printed on the tubing every few feet.

I suspect my system pressure will be way below those pressure ratings. Perhaps 15 PSI?

Paul Pollets

Warranty

Uponor/Wirsbo stands behind their product. I'd still be using copper or PAP.

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