using a boiler in my shop. can I use PEX?

timgman · February 3

I'm looking to use a Utica boiler svb-3 series 3 in my shop. If I set the hight limit ti 150 degrees, can I use PEX for the runs?

hot_rod · February 3

You want to keep the pex protected from UV, maybe insulate the runs. Sunlight for sure, some UV from fluorescents

ID of pex is smaller than copper tube, so calculate flow rates. The PPI website has flow calculators

Intplm. · February 3

https://forum.heatinghelp.com/discussion/200348/using-a-boiler-in-my-shop-can-i-use-pex

You can set it even higher than 150. And you should to help protect the chimney. Too low and the by products of combustion can destroy the inside of a chimney. Using FostaPex by the Viega company, rate that tubing to 200 deg, F.

Its very sturdy and can hold up to the riggers of garage/shop use too.

GroundUp · February 3

https://forum.heatinghelp.com/discussion/comment/1839958#Comment_1839958

FostaPex has been discontinued for a couple years already

mattmia2 · February 3

Regular PEX is fine at the temps and pressures of a residential hot water boiler. I suppose painting would also protect it from UV.

Intplm. · February 4

https://forum.heatinghelp.com/discussion/comment/1839970#Comment_1839970

Holy $%##@^! I didn't know that! A couple years?! Thats an awful shame. I was just using some this past summer too.

GroundUp · February 4

https://forum.heatinghelp.com/discussion/comment/1840091#Comment_1840091

Yes, quite awhile already unfortunately… I went to order some about 2 years ago and was told it had been discontinued, but they had one stick left in stock which I promptly grabbed. Not sure if it was an approval thing or a lawsuit thing (like many other PAP products) or what it was about, but it was a great product in my opinion.

hot_rod · February 5

There were some delamination issues poping up. Although it didn't affect the integrity of the tube.

It wasn't really a PAP tube which has an aluminum layer inside the tube layers.

It was their standard "black" pex with an outer layer of aluminum and PE wrapped around it. That is why you had to strip the outer layer to get to a regular SDR-9 pex tube underneath. So any pex fitting would work.

I'm hoarding a coil or 1/2" and some straight sticks of 1"

GroundUp · February 5

Yes I know what it was, but it still utilized aluminum which was the root of the delamination and therefore lawsuits in PAP products. Also, expansion type fittings were not an approved option as Viega never had a Pex-A product.

Intplm. · February 5

https://forum.heatinghelp.com/discussion/comment/1840358#Comment_1840358

That last sentence. I find very interesting. I don't believe Viega has distinguished between the "A" and "B" pex types? Was, or is it because they don't offer expansion? Probably. SiouxChief offered an expansion pex "B" that was "introduced" during covid. I haven't seen it since. Any insight?

hot_rod · February 5

I see several of the B pex now approve expansion fittings. Sioux Chief and Zurn are two.

Screenshot 2025-02-05 at 10.04.00 AM.png

GroundUp · February 6

PureFlow is a Pex-B, per Viega. They have many studies and videos out there comparing their products to cold expansion/ Pex-A and it's quite apparent that they will not allow cold expansion with their tubing. I've personally run across a few instances in the field as well as ran a few tests myself using cold expansion with Pex-B and C with no apparent trouble, but I'd imagine under certain circumstances it'd fail prematurely. The Sioux Chief in particular, being orange in color, when expanded turns white which looks very sketchy but it seems to hold just fine. I did the same with a chunk of cheap BlueFin tubing and it also turned nearly white, but the sidewall of the tubing blew out before the expansion joint did… Technicalities, I suppose, but the point was that Viega does not approve expansion fittings for their tubing.

using a boiler in my shop. can I use PEX?

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