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Old 11-02-09, 12:09 PM   #1
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Default DIY Hydronic Floor Heating

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Hello all...

I have noticed that there is interest here at Ecorenovator in hydronic floor heating (AKA: radiant floor heating). Also, because of the friendly relation between Ecomodder and BuildItSolar, I should mention the great interest in hydronic heating on that site.

In my thread, Homemade Heat Pump Manifesto, there have been several posts that contain questions or information about hydronic floor heating, and I thought it would be a good idea to create a new thread as a repository for that information and for future conversation and information.

A few basics:
  • Hydronic heating uses heated water flowing into some radiating device to provide heat to an enclosed space.
  • Hydronic floor heating uses an entire floor as a radiating device to supply heat to an enclosed space.
  • Since the area of the floor can be considerably larger than the area of a typical radiator, the possibility exists that the temperature of the working fluid in the floor can be lower than the temperature of the working fluid in a typical radiator, to satisfy a given heating need. It is because of the lowered required temperature that the potential for greater efficiency can be found.
  • Typical hydronic floor heating schemes include (in order of efficiency):
    1. On-slab concrete floors with embedded water-circulating pipe. These floors are typically 3 inches (< 7 cm) thick and are insulated, at least at the perimeter, with plastic foam insulation, from the earth.
    2. Above floor installation, wherein a thin concrete (about 1.5 inch) or another thermal conducting layer carries water-circulating pipe.
    3. Under floor installation (AKA: staple-up) wherein water circulating pipe is affixed underneath the existing floor, often with aluminum spreader-plates to enhance thermal transfer. For this scheme to be effective, insulation underneath the water circulating pipes must be very good.

As I understand it, in Europe where energy costs are very high, hydronic floor heating accounts for around 80% of new construction, with the remaining 20% accounting for all other forms. In the US, where our energy policy is essentially subsidized by our military spending, hydronic floor heating accounts for less than 10% of new construction, with the remaining 90% accounting for all other forms.

The best reference book I have found so far on the subject is Modern Hydronic Heating by John Siegenthaler. It is expensive but very thorough.

However, it does not address DIY approaches and is pretty light on 'Heat Pump + Hydronic Floor Heating' which offers very high efficiency. Topics like 'Solar Assisted Heat Pumps + Radiant Floor' go un addressed.

(* NOTE: the URL for Modern Hydronic Heating does list other books, apparently by other authors that do address other interesting approaches (solar thermal, etc.) to heating. Also on this site is a download section where 15-day trial software, pertaining to hydronic design, is available. Much can be learned from trial software. *)

For approaches like DIY retrofits, where benefit per dollar can be greatly enhanced by scrounging, re-purposing and completely novel thinking, enormous potential can be found.

Yes, this time, David can really kick the Giant's butt.

Some useful links:

Best Regards,


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Last edited by AC_Hacker; 07-16-12 at 10:51 AM.. Reason: inclusion of other references...
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