ASTM standards for pex tubing

Mark_46

Tom,

To me your post is very timely. I was going to start a new thread on below.

All,

Along the lines of PEX standards...does anyone know how PEX is rated in terms of heat loss? Is there a document or website showing this? Should PEX tubing carrying hot water be insulated?

Water boy

astm standard for pex tubings

Were can a guy find the standards for astm on pex production in the USA.

Brad White_9

From my guide spec

USA – ASTM

F876-04 Standard Specification for Crosslinked Polyethylene (PEX) Tubing

F877-05 Standard Specification for Crosslinked Polyethylene (PEX) Hot and Cold water Distribution Systems
F1281-03 Standard Specification for Crosslinked Polyethylene/Aluminum/Crosslinked Polyethylene (PEX-AL-PEX) Pressure Pipe
F1282-03 Standard Specification for Polyethylene/Aluminum/Polyethylene (PE-AL-PE) Composite Pressure Pipe
Status – All published

Und chest fur fun:

German – DIN

DIN 16892 Pipes made from crosslinked PE (PEX) – General requirements, testing

DIN 16893 Pipes made from crosslinked PE (PEX) – Dimensions

Status – published (2000)


DIN 16895 Crosslinked medium density polyethylene (PE-MDX) pipes - Dimensions

Status – Published (1996)

DIN 4726 Warm water floor heating systems and radiator pipe connecting - Piping of plastic materials

Status – published (2000)

Mark_46

All,

To me your post is timely. ALong the lines of PEX standards...does anyone know how PEX is rated in terms of heat loss? Is there a document or website? Should PEX tubing carrying hot water be insulated?

Brad White_9

Good question on conductivity.

I know there is data, not sure of a standard.

As for insulating, I make it a practice to specify that my homeruns be insulated where I do not want them to impart unwanted heat. I specify 3/4" Armaflex for that application. A recent I designed was the Williams College '62 Center for Theatre and Dance, in Williamstown, MA. The radiant floor system heats a "Glass Cube" entry lobby and rather well in this sub-zero design area. The homeruns to the manifold go to the interior where other forms of heating dominate so we did not want a "lopsided" effect heading to the left as you enter...

So yes, where heat is not wanted, I would insulate.

Jerry_15

Right on Brad. It's not only unwanted heat, but wasted heat; and if it's run in concrete, considerably more heat loss through conductivity than when hanging in the breeze. I always insulate dead runs on DHW; on radiant I try to use it to heat a space (like a hallway), without adding an extra zone. It's arguable that the heat loss, even in a wall, adds to the building envelope, but I'd rather put it where it's needed.

Mark_46

Had a feeling

Brad,

Thanks, your a great source of info.

I had a feeling it should be insulated but wasnt sure because I would think plastic does not conduct heat as well as copper.

Brad White_9

Mark, Jerry-

Thank you and you are both welcome. Happy to help if I can.

And you are right, Mark, PEX does not conduct as well as copper, but gosh it is remarkable stuff considering that.

As Jerry said, embedded in concrete has great conduction and no quick "off switch" I would add.

On the Williams project, I would love to go back next winter and map the floor temperatures on the homeruns. When I was there last, March 20th to be precise, it was quite comfortable to the hand even with all that bluestone. Moving inboard above the insulated homeruns, it seemed "cooler" but by no means cold. It was fractionally warmer than off to the right where no homeruns were placed, but that may just be "my expectations". Not scientific by any means!