# PB pipe radiant heat system.



## rusty_5620 (Aug 23, 2006)

Hi there,

I just opened up the subfloor and discovered QEST C-PB2110 Potable Tubing being used for the radiant heat system.
The house was built in 1989. Is this piping an issue or is OK in a closed loop system
with minimal fittings?

Cheers,
Rusty


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## thom (Nov 3, 2006)

PB was promoted pretty heavily by Shell Oil for use in radiant systems back in the 1980's. I put it in my own house in 1984. To date, I've had no problems. The failures in PB systems were typically in the connections, the copper connectors would fail. Your heating system should have much less pressure so the joints should be less susceptible to failure. Still, you should keep an eye on the system.


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## Willie 2 (Feb 4, 2010)

Is there any concern doing the reverse, I wanted to use radiant heat tubing in my new home for plumbing lines of the water supply. The pipe seems to have a thicker wall than the regular store bought product and is labelled ASTM F876 / F877' 100psi / 180 degree rating, Potable tubing. Pex fittings seem to fit well into the ID.


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## protechplumbing (Oct 10, 2008)

Your ok. The PB failures were related to the chlorine in the water and high pressures. Neither is present in a radiant system. I wouldn't let it keep me up at night.



rusty_5620 said:


> Hi there,
> 
> I just opened up the subfloor and discovered QEST C-PB2110 Potable Tubing being used for the radiant heat system.
> The house was built in 1989. Is this piping an issue or is OK in a closed loop system
> ...


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## UALocal1Plumber (Jun 19, 2009)

Willie 2 said:


> Is there any concern doing the reverse, I wanted to use radiant heat tubing in my new home for plumbing lines of the water supply. The pipe seems to have a thicker wall than the regular store bought product and is labelled ASTM F876 / F877' 100psi / 180 degree rating, Potable tubing. Pex fittings seem to fit well into the ID.



As long as the tubing is rated for potable/domestic use, you'll be fine. Call the manufacturer and ask them to email the spec to you, double check the numbers against the actual product you'll be using, and everything will be OK.

Remember that the fittings have to be approved for use with the tubing you will be using. You can't mix and match and expect there to be a warranty. Make sure to buy the proper fittings for the tubing, and join them in the approved fashion - otherwise, all bets are off.

Also remember that PEX fittings are barbed into the inside of your tubing. This will cause flow restrictions and turbulence in excess to what is experienced with copper tubing installations. The greater wall thickness of the PEX will also increase your friction loss further than copper. 

So as a rule of thumb, upsize your PEX shots by one size in order to make sure you have acceptable pressure at each outlet. The reduced cost of the material will more than offset the larger size lines.

Keith


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