You are here:

Radiant Floor Heating/PEX no oxygen barrier, what now?????


I read your answer:

I am in the process of purchasing a renovated house which just had the boiler replaced with a new Burnham MPO-IQ and in-floor heat.  Unfortunately, the contractor used non Oxygen-barrier PEX tubing, and has already been paid so our leverage (buyer and seller) is limited.  The system is not using glycol but the water is probably not soft water either.

What are our options (low to high cost) for fixing the problem which will ensue in a few years?

From the referenced post it sounded like you recommended replacing the boiler in any case (but was that just because the existing one was already damaged?)  In our case, the boiler is new.  Would putting in a heat exchanger between boiler and PEX tubing, with soft water in the boiler, be our best option?  If so, what would you recommend and how much should we expect to pay?

We installed nothing but polybutylene (PB) without and oxygen barrier
back in the day. Millions of feet of non-barrier PB were sold in the early 90's with little trouble. Of course we used a stainless steel condensing boiler almost exclusively and most of the systems were radiant floors running at low water temperatures.

In the case of an atmospheric boiler such as the Burnham MPO-IQ the cast iron will not like an oxygen-rich heat transfer fluid. We would use a Fernox or Sentinel cleaning product to chemically scour the water side of the boiler and distribution system followed by a proper flushing and final treatment, perhaps isolating the non-barrier PEX after flushing.

Once treated the boiler and other ferrous metal system components should be decoupled from the PEX tubing with a SS plate heat exchanger and a sub-system designed and installed with non-ferrous components, e.g. bronze or SS circulators, potable water expansion tank, etc.

Non-oxygen barrier tubing (PEX) is still used quite frequently in commercial systems as it costs less than barrier PEX and is easily isolated from systems components that might suffer from prolonged oxygen exposure.  

Radiant Floor Heating

All Answers

Answers by Expert:

Ask Experts


Morgan M. Audetat


Radiant panel heating design, including floors and ceilings, European wall panels and snow melting for residential and light commercial buildings..............................................................-Master of Steam and Hot Water,City of Minneapolis....................................................--- Master Plumber, State of Minnesota...........


30 years..... Charter Board Member - Radiant Panel Association, former manufacturer of condensing boilers, former national distributor of radiant floor products, son and apprentice of mechanical & plumbing contractor. Current mechanical/plumbing contractor specializing in hydronic based, integrated HVAC systems. Radiant floor heating/cooling. Snow Melting. Condensing Boilers. Indirect water heaters. System design, consulting and technical training world-wide. Licensed contractor, designer, installer and consultant.

B.S. University WI 1981 CONTINUING EDUCATION: Viessmann Condensing boiler and Solar water heating certification 2010, N.D.S.U. Lead Worker RRP certification 2010, Knight condensing boiler certification 2009, Wrightsoft Manual J CAD certification 2009, RPA Designer & Installer Certification 2008, Nate Hydronic/Forced Air Certification 2008, Uponor/Wirsbo advanced design school certification 2007, Buderus Wall-hung certification 2007, Power Limited License (low voltage controls) 40 CE credits 2005, Basic Hydronic Certification IPEX & Northern Alberta Institute of Technology 1998, Charter Board Member - Radiant Panel Association 1994, Residential Off-Electric to Hydronic Conversion Heating School Canadian Hydronics Council 1994, B&G Little Red School House 1993, Rood Utilities (now Auburn Technical Institute) Oil Burner School 1993 ,Tekmar Controls residential and commercial 1993, Division Manager and Advanced Hydronic Seminar Instructor for the first Exclusively Hydronic Radiant Floor Distributor in the USA 1990, Hydronic Radiant Heating Association Workshop participant with Richard c. Bourne, PE spring 1988, Master Plumbing, Hydronic, Solar Course Red Rocks Community College 1987.

Awards and Honors
2009 System Showcase Award - Radiant Panel Association

©2017 All rights reserved.