[Greenbuilding] solar heat collection

Clarke Olsen colsen at fairpoint.net
Wed Jul 4 14:36:57 CDT 2012


    Corwyn,
    Thank you for your considered advice.
     1. 1000 gal was the biggest (5'x10'x4' low boy concrete septic) tank that I could squeeze in the crawl,
          before the house went on.
     2. Bottom to top is obvious, though it seems that loops pulling heat out should be high in the water, 
         and one putting heat in could stay on the bottom. 
     3. I have no calculation.
     4. My collectors will mount on ground level frames against the south wall, making adjiustments easy,
         and inviting drain back. Tilting back to catch summer sun inceases the effective area by 50%.
     5. The house went through last winter with just the booster to heat the floor. Oh, yeah, and a wood stove.
Clarke Olsen
373 route 203
Spencertown, NY 12165 
USA
518-392-4640
colsen at fairpoint.net


On Jul 4, 2012, at 2:35 PM, Corwyn wrote:

> On 7/4/2012 2:02 PM, Clarke Olsen wrote:
>>    I am putting together a system with tilt-adjustable panels and a 1000 gal storage tank, in the hope of collecting
>> and storing heat year round. The 1400sqft house has radiant tubing in a 3" concrete floor sitting on 1/2" foam over
>> a crawl space. The boost from the tank temp to hot shower is handled by Eemax 6.5kw point-of-use instant water
>> heaters. The floor circuit also has an Eemax booster. My plan is to run both the domestic hot water and the floor
>> circuit through heat exchangers in the 1000 gal storage tank.
>>    My question is: should the storage water run through the collectors directly in a drain-back configuration, or is a
>> closed-loop, heat exchanger be preferable? This would make 3 sets of loops in the tank, with the collector circuit
>> on the bottom.
> 
> Drain back is more reliable (fewer things to go wrong) but it requires a larger pump to handle the head.  If your collectors aren't much higher than your tank, I would consider a drain back system, otherwise a closed loop.  Or, if you are prone to power outages, go closed loop on a solar panel controlled pump.
> 
> Other notes:
> 1. I think 1000 gallons is probably too large (or not large enough) depending on your goals.
> 2. The heat exchanger loops should be side-by-side.  With the collector loop flowing top to bottom, and the other two flowing bottom to top.
> 3. I recommend that you work out the math for the energy flow, if you haven't (if you have, post it here to give us a better idea).
> 4. Adjusting tilt on water collectors is going to be a royal pain.  And probably not needed.
> 5. I would forget the booster on the floor circuit, too high a current needed, and the control circuit would need to be pretty sophisticated. If you need supplemental heat just get a cheap heater (again, depending on a number of details).
> 
> Thank You Kindly,
> 
> Corwyn
> -- 
> Topher Belknap
> Green Fret Consulting
> Kermit didn't know the half of it...
> http://www.greenfret.com/
> topher at greenfret.com
> (207) 882-7652
> 
> 
> 
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