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polyethylene tubing for radiant heat.....good or bad???

Unknown
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in THE MAIN WALL
PB can last a very long time depending on how high temperature you hit it with and how well it was installed (cushoned). it turns pretty darned soft at those temperatures but, lots of it still in use. Hi & low temps.

Be sure you're not using any ferris components in your system. That stuff lets in those pesky little oxygen molecules. The bane of the conventional hydronic system.

*To catch up with me real time, try AIM. User name: Radiantfloors

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Comments

  • Harry_2
    Harry_2 Member Posts: 2
    polybutylene tubing for radiant heat system

    I have recently had an inspection done on a radiant hot-water system. The inspector told me that polybutylene tubing from the manifold to baseboard heaters will fail prematurely because it is not rated to withstand the ~180 degree water temps. The house is only 12 years old and in very nice shape. Shoud I be worried about the polybutylene tubing? Is it likely to last 2 yrs. or 20 yrs??
  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
    A few things to check first

    What temperature has the system been operating at and what temperature was it designed for? To find the design temperature, you need to do a heat loss analysis room by room....a heat loss program is available right here, courtesy of the folks from Slantfin. Then you need to find out the heating capacity of the baseboard per foor of element (Check with the manufacturer) and how much there is in each room. If the baseboard was sized to operate at low temperature, it may not be a problem.

    However you may have a problem with oxygen diffusion through the walls of the tubing. All components in the system must be non-ferrous... no cast iron or steel.

    Boilerpro
  • hr
    hr Member Posts: 6,106
    the weakest link

    in the original PB systems was the acetal (grey plastic) fittings. Make sure you don't have any of them. Most PB was non barrier, and allows O2 into the system. As others mentioned,protect the ferrous components with chemical treatment or seperation via a HX.

    There were some barrier PBs out there. As I recall Infloor was one. Check to see what brand you have.

    The PB hotline and relpacement program is still in effect. You might call them for more info on warranty replacement, if any :)

    hot rod

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  • Dave Yates (PAH)
    Dave Yates (PAH) Member Posts: 2,162
    poly-bute

    We ran into this situation a few years back when an iron pipe driveway snow-melt system blew out a fitting from freezing. There was NO glycol in the system!

    At any rate, they wanted a new zone in a sidewalk being replaced, which became PEX with O/2 barrier. The iron pipe was repaired by cutting away just enough mecadam for access. However, the front sidewalk and porch were done using PB piping sometime in the past (about 5 years prior according to the HO). That lead to further investigation and discovery of serious deterioration of the boiler.

    A new boiler was installed along with a Flat Plate HX. Now the boiler side has water; the FP HX has a freeze stat bulb on its return line to prevent damage on the boiler's side; and the snow-melt zones each have their own sensor and circ while being protected with glycol. No auto-feed on the glycol side, which was what killed the original iron piping. (We think a small leak lead to constant replacement of glycol laden water with fresh.)

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  • Harry_2
    Harry_2 Member Posts: 2
    polybutylene tubing for hot-water heat

    Polybutylene tubing for basebrd. radiant heaters......can they withstand the ~180 degree water temps. from the boiler to the basebrd. heaters??? I'm looking at buying a 12 yr.old house with polybut. The water supply is from a city well so no chlorine is added. The water currently coming out of the boiler is about 160 degrees. A mixing valve has been suggested, will that help cure the problem? Any predictions on how long the polybutylene is "likely" to last??
    Harry
  • Floyd_5
    Floyd_5 Member Posts: 418
    Harry,

    I would be very cautious....
    I redid a system this summer that had PB tubing, the homeowner called because his expansion tank failed for the 3rd time in 6 years....also his Trianco boiler was giving him a ton of trouble.
    Explaned to him the problems with O2 and the PB...his tubing was still plyable, so I recommended a new boiler and a flate plate heat exchanger. He has enough baseboard installed that he can keep his temps down and still heat effectively.
    In your situation, I you will have to check out the situation and detrimen whether you have sufficient baseboard to still heat the house at say 150 or 160....obviously the lower temps you can run the more chance you have of making the PB pipe last longer.
    If you are considering buying this house you may want to first have someone come in,do a heat loss,check the baseboard and it's ability to heat at lower temps. and then decide whether or not you want to take a chance on this house. Or...maybe you just want to buy the place and plan on redoing the heatng system.
    No easy anwser to your questions...

    By the way...do you know what type of boiler the place has???
    If it is of the cast iron or steel variety your may be looking to replace that in the near future, also.

    Hope that has helped with some of your questions.

    Floyd
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