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Radiant Floor Heating/Radiant System Design troubles poly-B


I am looking for some advice.  I have spent alot of money on my radiant flooring but it has not seem to be money well spent.  I have poly-B tubing throughout my house.  The top 2 levels have the tubing going between the joists and the basement it is in the concrete.  The plumbers last year installed a Weil Mclain CGA-8 177000 btu cast iron boiler.  The water going through the lines was too hot so they installed a 3-way mixing valve that when I use causes the pressure to go above 30psi.  As a result I turned the boiler down to 140F.  This I know is not good. There is also inadequate flow to the top levels as the rooms get cold in the winter time and I have to use electric space heaters to keep the kids rooms warm.

I paid for advice from an individual and he suggested using a triangle tube smart 80 as the heat exchanger to separate the boiler loop from the house loop.  It would also act as a boiler buddy to limit they cycling problem I am having.  I went to price it out and the hydronics expert at the distributor said that is not a good idea.  He suggested a plate heat exchanger is the better route. I trust the first individual as I see him as an expert.  Any advice would truly be appreciated as I want this system to work and last.  

Thanks  Jamie

Badger Boiler Service Versa Hydro combi
Badger Boiler Service  
(poly-B)? Polybutylene (PB) has not been available in the US for more than a decade. It was a very excellent radiant floor tube and we sold some with an oxygen barrier before the trial lawyers convinced Dow Chemical that it was not worth their trouble.

The hotter your design water temperature the faster the rate of oxygen diffusion, so we design radiant floors for the lowest design temperatures possible making machines last longer, burning less fuel and increasing comfort.

We rarely use low efficiency cast iron boiler, more especially when designing radiant panel systems as they require proper mixing controls to protect the boiler from condensing and the radiant panels from over heating.

If you have in fact non-barrier PB or any non-barrier pipe then a heat exchanger would seem appropriate. We use both indirect water heaters and stainless steel heat exchangers to isolate such systems...after doing the math.

On the last such radiant floor system installed by a DIYer, we specified and installed a HTP VersaHydro answering both questions at once.

A smart, experienced radiant floor heating designer can answer your question after collecting all the evidence.  

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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

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