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Old 02-12-15, 08:25 AM   #11
gtojohn
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Doing a little homework on hydronics in the South. It can be desireable to not heat the slab be cause of our sudden temperature swings, 82F yesterday and 58F for today. Looking at some info from Homepower, 110F for solar hydronic floor heating and 120F for radiant wall. With my overall floor plan I'm considering a radiant common wall on the interior and loft floor/kitchen ceiling to minimize losses to the exterior. And maybe 2 fan coil units to speed up heating when the sun is really shining.

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Old 02-13-15, 06:00 AM   #12
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Given your heating needs, you can do all the heating with 30C (85F) water and that makes the floor attractive. You will gain in the day and lose it at night. The slab will be close to natural body temp so it will not feel too hot nor cold. Pump directly into it through a small buffer tank, 30% propylene glycol (might be 40% as I don't know what your coldest temp is). Use a ductless heat pump to top up if need be (or make a converted window shaker into a air to water HP as top up). Threads abound on here for instructions.
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Old 03-19-15, 12:09 PM   #13
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What did you end up doing? Did you get all 3 panels? Pics?
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Old 03-19-15, 04:41 PM   #14
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Yes, more input please. And while you're at it, could you add some detail to this statement you made in an earlier post, "Perhaps 1-2 radiators will be all I need to take the chill out. I've found some 16x20 heat exchangers for less than $100. " Obviously, the emphasis I added, and I'd like to have a look at those myself.
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Old 03-19-15, 06:45 PM   #15
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Quote:
Originally Posted by gasstingy View Post
Yes, more input please. And while you're at it, could you add some detail to this statement you made in an earlier post, "Perhaps 1-2 radiators will be all I need to take the chill out. I've found some 16x20 heat exchangers for less than $100. " Obviously, the emphasis I added, and I'd like to have a look at those myself.
What do you mean by "16 x 20 heat exchangers"?
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Old 03-20-15, 02:28 AM   #16
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http://ecorenovator.org/forum/renova...country-2.html
Pier and beam. Slab quote was over $4k. This was less than $1k. Additional benefits of a crawl space include room for a composting toilet storage tank as well as my water pumps and hot water storage tank. Walls have been completed and I hope to be dried in is about 2 weeks. For heat exchangers I found them on ebay under "water air heat exchangers". I have a few plans for heating including a copper water coil close to my wood furnace to help boost the output when occupied. There will be 1 to 2 minisplit heat pumps mostly for cooling. My main strategy is to insulate and build as tight as affordable and reduce my heating requirements and let the solar do what it can when unoccupied. Sadly winter ended about 2 weeks ago. Its been in the mid 70's lows in the 60s, today made it to 83f with high humidity.
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Old 03-21-15, 04:10 AM   #17
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I found a little info today. "For flat panel collectors expect 1000 btu per sqft per day in the south. In a more northern latitude expect 750 btu*sqft day. 10-20% of building sqft was recommended for sizing to provide 25% of annual heating demand. Also recommended 5 gallons of water per sqft of panel for storage will increase coverage to 50% of annual heating demand."
So in theory I can expect 63,000 btu output on a sunny day and 315 gallons of storage can help buffer for a cloudy day. Im already undersized for a 1000sqft space, man j shows 11kbtuhr on a 30f day (264kbtu day). Manipulating manual j with the panels I have I can expect to keep 6f above outdoor ambient. So, 240 sqft could help keep me closer to 18f above outdoor ambient and quite a bit more comfortable as a starting point before other heat sources.
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Old 03-21-15, 04:45 AM   #18
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Quote:
Originally Posted by gtojohn View Post
http://ecorenovator.org/forum/renova...country-2.html
Pier and beam. Slab quote was over $4k. This was less than $1k. Additional benefits of a crawl space include room for a composting toilet storage tank as well as my water pumps and hot water storage tank. Walls have been completed and I hope to be dried in is about 2 weeks. For heat exchangers I found them on ebay under "water air heat exchangers". I have a few plans for heating including a copper water coil close to my wood furnace to help boost the output when occupied. There will be 1 to 2 minisplit heat pumps mostly for cooling. My main strategy is to insulate and build as tight as affordable and reduce my heating requirements and let the solar do what it can when unoccupied. Sadly winter ended about 2 weeks ago. Its been in the mid 70's lows in the 60s, today made it to 83f with high humidity.
OK, Interesting quote for the slab. I just did a 1200ft slab at 4" and the concrete cost $3k and the finishing cost $2k.
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Old 03-21-15, 07:56 AM   #19
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I was quite surprised at the quote for concrete for Gtojohn. I had made a comparison in an earlier post between the wood floor construction and heated concrete slab and I still find the heated slab is less cost expecially when the extras (ductwork & heatexchangers) are factored out.

Now I do understand Gtojohn already had some wood But.
I think its a lot less work. Two to three days and you have the main-floor finished.

Mikesolar what do you think of two separate loops one for solar and another for radiant heat. instead of trying to heat exchange into one main loop.

Maybe another thread on some of these ideas.!

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Old 03-21-15, 08:00 AM   #20
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I had thought about separate loops for solar and backup heat before. I wanted to have the solar at the bottom of the slab, tempered down temp of course. The backup heating would be sitting higher in the slab. Won't work well with a 2" slab but it would with a 4' slab. You could still have a diverting valve to do solar DHW.

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