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Radiant Floor Heating/Combi tankless for space and DHW heating


Can you use a propane on demand hot water system to supply the hot water for a radiant heating floor and domestic use??
Presently I use a 60 Gal. propane fired hot water tank for both the floor and domestic hot water use.

Thanking you in advance for your opinion.

You are describing an "open" heating system. Yes you can use an "on-demand" or "tank-less" water heater to heat space and domestic hot water, but it doesn't mean you should. Most radiant floor system components are not yet rated NSF for potable water.

Water heaters also lack energy saving features that come standard with all condensing boilers such as, outdoor reset. Outdoor reset increases comfort, lowers the heat load and fuel bills all at once.

The longevity of domestic hot water heaters that recirculate potable hot water are also in question as the typical tank or tank-less is not made for the duty cycle a boiler will see during normal operation.  

We design many small radiant heating systems using various condensing boilers, combi boilers and water heaters, but always separate the drinking from the heat water for better efficiency and longer system life.  

Radiant Floor Heating

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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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