(C) Daniel FriedmanRadiant Slab Tubing Leaks
Causes & repairs of leaky radiant heat tubing

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Radiant heat tubing leaks:

What causes leaks in tubing or piping used for radiant heat in floor slabs and what repair options make sense when the radiant heat system is leaking?

This series article discusses the suitability of various tubing materials for radiant heated concrete floor slabs, and choices of heat conducting fluids for radiant floors.

Our page top photograph shows polyethylene tubing being installed in a new concrete floor slab for radiant heat in a Two Harbors Minnesota building.

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Radiant Floor Slab Tubing Leak Causes & Remedies

Radiant floor tubing types (C) Daniel FriedmanReader Question: what can you tell me about Entran II leak-risk radiant heat tubing and how can I recognize it in a home?

I have heard that Entran radiant heat tubing is a problem. Is that correct?


Early Entran™ Tubing marked Entran or Entran II is at risk of leakage and failure where it is installed, particularly if the tubing was subjected to high temperatures. Entran-3 tubing does not have the same leak complaint history.

Our photo (left) illustrates Entran-3 radiant heat tubing - not the leak-prone product discussed here.

Entran radiant heat tubing, produced by Goodyear Tire & Rubber and was distributed by Heatway Systems between 1989 and 1994 and has been estimated to have been installed in abouit 10,000 homes in the U.S. and possibly in Canada. Specifically Entran-II was a rubber tubing product installed for radiant heat floors. It was also installed in driveway or sidewalk snow and ice melting systems.

The defect of concern with Entran-II tubing is that a plasticizer added for flexibility was found to leach out of the rubber if it was exposed to high temperatures. The loss of the plasticizer was associated with odor and smell complaints and ultimately with leaks in the tubing as with loss of plasticizer the tubing will crack.

We encountered this product first as part of an investigation into an odor complaint in a new home with radiant heat tubing stapled under hardwood floors. The installer, hoping to "drive out" the odor, ran the heating system at higher-than-recommended operating temperatures, leading to a double fault: the flooring was damaged (gapping) from the excessive temperature and ultimately the tubing leaked.

You may identify Heatway Entran II tubing by noting its orange color and imprinted markings where you see radiant heat tubing at the supply and return radiant tubing manifolds that are usually close to the heating boiler.

Entran II or Entran 3 radiant heat tubing identification photos (C) Daniel Friedman\

If the tubing was stapled-up beneath a wood floor and subfloor, by moving insulation (you may have to also remove ceiling coverings) you can also inspect the tubing and its condition.

In our OPINION unless you already see visible leaks, cracks, or damage, it is not easy to determine the remaining life of the Heatway Entran-II tubing. If the tubing was never subjected to high temperatures (which should have been the case with a properly installed and operated radiant heat floor system) the remaining life could be good.

If you suspect that the tubing is already leaking (leaks may not be visible if tubing is embedded in a concrete slab) a pressure test or infra-red scanning and thermography can not only detect the leak but can detect where it is occurring. Of course if the tubing has leaked in a finished ceiling you'll probably see water stains.

Class Action Settlement May Offer Financial Relief to Homeowners where Entran II Tubing Was Installed

Only for homeowners who filed a claim prior to 19 November 2009, a financial settlement offered limited damage payments for homeowners in two categories, depending on the actual extent of leak damages that occured due to Entran-II tubing.

The product names involved included Twintran, Nytrace, Entran II Trace, Entran II Wire, Entran 2, Entran 2 Trace, and Entran 2 Wire. Details were at or could be obtained by calling 800/254-9222. A follow-up check of these contacts in 2012 lead nowhere.

Details about PEX tubing and other plastic tubing choices are at

Question: how to fix leaks in radiant heat tubing in a slab

Jan 1, 2017 Anonymous [by private email) wrote:

I have had radiant heat in a concrete slab for a little over 10 years now it was wonderfull ,but six months ago it started leaking we found the leak and busted the concrete and found a pin hole in the hose. spliced the hose fix and check had no leak. in the last six months have had 3 other leaks, all in different places. had to replace the laminate floor twice.

I shut the valves and blowed out the lines, but the floor is now too cold for my wife. was wondering if it would be possible to install a smaller hose inside the7/8 pex hose with maybe a1/2 inch hose? i have two zones with open syestem ,app 190 ft total - Anonymous 2017/01/02

Reply: options for re-lining or repairing leaky radiant heat tubing in a slab?

Interesting idea and not one I've seen before. There are pipe relining systems for larger diameters, principally for drains. I worry that your piping reliner won't push past connectors even if otherwise you could shove it through the tubing.

There are other relining options such as using a cured in place piping repair (CIPP) or an internal coating, epoxy or something else.

CIPP is described at TRENCHLESS PIPE REPAIRS where we also list some vendors of that system.

NuFlow provides an expoxy relining system: intended for re-lining by coating copper or galvanized pipe. I'm not sure it's rated for plastic piping (assuming that's what you have) in part because plastic flexes. But you might ask the company how their system would work on flexible tubing encased in a concrete floor.

Epoxy Water Pipe Relining Systems

Watch out: there is some question of the efficacy of re-lining pipes. Questions include

  1. One cannot inspect the pipe interior to see where the lining material adhered or didn't adhere so you could be spending a wasted sum with an unpredictable life far less than the typically-claimed 60 years
  2. Adhesion of these liners may not work at all on plastic piping such as PEX
  3. If the pipe is already corroded, thinned or leaking, then the "repair" is itself very thin at that location - that is there's only the liner, no pipe material. Under pressure and temperature such a repair may be short-lived.

Research on Epoxy Water Pipe Relining System Effectiveness & Life

If you can, send me photos of the floor, the tubing, the opening you cut, the hole you found, and the repair. That will let me comment in a way that at least *sounds* smarter. <g>

Other questions about change in heat transfer through a double-thickness of pipe make assessment of the effectiveness tricky too. You might think about increasing water velocity and temperature but that, in turn, risks exceeding the temperature rating of the tubing. See RADIANT HEAT TEMPERATURES

Finally, where did the leaks occur? What can we say about cause? Were pinholes in the tubing or in brass connectors?

If leaks are being found at the connectors used in your radiant heat piping, see PEX BRASS CONNECTOR LEAKS


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