11-02-09, 12:09 PM | #1 |
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DIY Hydronic Floor Heating
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:
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, -AC_Hacker Last edited by AC_Hacker; 07-16-12 at 10:51 AM.. Reason: inclusion of other references... |
11-02-09, 12:29 PM | #2 |
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Excellent idea AC Hacker. I'm working on getting my own copy of that book for reading. It seems to be the only worth while one out there. Sadly, since hydronic heating is used in such a small amount of US homes, I doubt we'll find a ton of good material on it elsewhere. If anyone has any good links, please share them.
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11-04-09, 08:28 PM | #3 |
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Thoughtful Discussion Regarding Radiant Floor Heating...
I found a link to a page with a very thoughtful discussion regarding radiant floor heating. I found it particularly interesting when radiant floors are considered in the context of High Performance Buildings, and how radiant floors may never develope that 'warm feeling' in a High Performance House because so much of the radiating heat is retained by the house, that lower floor heat levels are called for.
I have been to some lectures regarding 'High Performance Buildings', and they don't use that term lightly. High Performance Buildings are very similar to the Passive House definition. To achieve those levels of performance, buildings needs to be High Performance by design. Stringent efforts to retrofit existing structures can result in achieving 35% to 50% of the Passive House standards. So I think that 'warm feeling' would still be there. Also, the discussion apparently assumes that no one would DIY a radiant floor. So their cost estimates are stratospheric by DIY standards. Regards, -AC_Hacker |
11-04-09, 09:56 PM | #4 |
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DIY Radiant Floor Heating links...
I talked with a local hydronic guy who told me that around here, feed water temperatures are:
* * * And just to get the thought process moving, here are some radiant floor links...
Last edited by AC_Hacker; 11-04-09 at 11:40 PM.. Reason: Links-O-Matic |
11-04-09, 10:52 PM | #5 |
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Good information! I plan on using radiant floor heating with a solar/water setup that thermosiphons, and using valves and a bypass loop for excess heat energy, with ~1000 gallons of stored fluid in thermos-like insulated tanks under ground, for the times that there isn't sufficient sunlight for days on end.
For fluid, I plan on either using salt/water, if I can get enough plastic tubing, or using a methyl/water solution. The fluid should never freeze, since the lines and tanks will be buried under the ground, so that they should maintain an atmosphere of at least 50*. I may have to go against the thermal siphon idea, though, because it may not work fast enough to actually keep the home warm. The floor is most probably going to be insulated poured concrete (which may end up being mixed with styrofoam beads) with an overlay. Some rooms may have partial brick/stone floors as well, which add thermal mass and thermal dispersion potential. (Acting like a heat retainer that also helps disperse heat across a larger surface area.) |
11-04-09, 11:50 PM | #6 | |
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Quote:
Last summer, I was testing the thermal conductivity of various aggregates in concrete, and one of my test aggregates was aluminum chips. Made sense, beings as how aluminum is light and a wonderful conductor of heat. What I didn't count on was that the alkaline nature of concrete made the aluminum fizz, and the concrete+aluminum puffed up with a ka-jillion little bubbles and was a worse thermal conductor than plain old concrete. The rest of your ideas sound really great. |
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11-04-09, 11:58 PM | #7 | |
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Quote:
So the actual floor layout is concrete/hybrid slab, fluid lines laid on top, flooring options laid over that. I figure 170* is more than enough to heat the floors and the rest of the house, right? (The temp that solar thermal setups can reach, even on not-so-great days.) |
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11-05-09, 02:28 AM | #8 | ||
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Quote:
Quote:
So many variables that it is really difficult to keep them all in your head at once. I would recommend getting some kind of computer simulation program and running it with different options to see how certain variations affect the outcome. You might try this link and download some of the trial programs, might give you some ideas. There was a really great program by a company called Slant Fin. The program was called Hydronic Explorer and you answered some questions about your house and it gave you your heat load, and you could play with the layout and get feedback on how it would affect everything. Maybe they would make the program available to you. Worth a shot. Regards, -AC_Hacker Last edited by AC_Hacker; 11-22-09 at 09:21 PM.. |
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11-05-09, 07:56 AM | #9 | |
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Quote:
Wow, that would indicate that in slab would be MUCH more efficient. Especially in a heat pump situation I'd imagine. I knew under floor had to be pretty hot, but its nice to see on top of floor in the mix too. Good info AC Hacker! I'll hopefully contribute to this thread soon, been so stinkin busy lately.
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11-05-09, 11:21 AM | #10 |
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AC_Hacker -
Thanks for those links, I'll likely check them out and see what I can come up with. |
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diy, heat pump, hydronic, pex, radiant |
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