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ChrisJ

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Posts: 94
Reply with quote  #11 
Pretty much finished the tank cover. Solar shed 23.jpg

The cover is fairly heavy, I may hinge it or just put handles.

Solar shed 22.jpg 
Mounted the controller and power switch.
 

dbc

Registered:
Posts: 132
Reply with quote  #12 
Chris, 

Great looking project, the collector and especially the tank.

I think you have a point about the fins conducting heat into the plywood, although it seems that would stabilize once the plywood heats up to the temperature of the copper (not sure what that does to the plywood long term).  You'd want a polyiso thermal break all around and behind the plywood and grid; it looks like you have that.

Your inverted fins idea is interesting; the question is - how you ensure a tight fit between the copper pipe and the fins?  Stapling the 'normal' way makes that easier.  I have seen a commercial Novan collector with the glazing off, and they have the pipe grid bonded (brazed?) directly to a copper or brass sheet.

I had the same experience with the brush-on vs, spray paint on my hot air collector.  I used Rustoleum # 7778 high-temperature grill paint.  The spray version was a lot flatter than the paint in the quart can.

Are you going to use copper coil heat exchanger(s) in the tank?
ChrisJ

Registered:
Posts: 94
Reply with quote  #13 
Thanks Don!

Yes I am going to make a copper heat exchanger, similar to the one another Chris made.  (http://simplysolar.supporttopics.com/post/n4kit-chriss-solar-thermal-project-6717362?pid=1292377050)

I discovered that if I use a regular elbow (90*) and a street elbow I save 1 solder joint at each u-turn. I am figuring 3 rows of 8 pipes 5' long, for about 120' of 3/4" copper pipe.

The inverted fin idea was originally thought of for CPVC pipe. Scott Davis used just a bead of caulk under each CPVC riser to a flat piece of flashing. So having the shaped fin go around the back of the pipe with caulk in the groove I thought would work better. 

The fins come with a bit of a "W" shape to them. So the groove closes up around the pipe when the 2 "sides" are pushed flat. I thought if I screwed through the fin near the pipe it would flatten the fin against the insulation. I think I will try it with some scraps I have left.








ChrisJ

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Posts: 94
Reply with quote  #14 
Solar shed 24.jpg  Solar shed 25.jpg I have built 2 of these, one for radiant, one for DHW. 120' of 3/4" pipe for each heat exchanger.



SolarInterested

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Spam Stomper
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Posts: 987
Reply with quote  #15 
Well done. Those look like store bought.
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Both temperature rise and airflow are integral to comparing hot air collectors
ChrisJ

Registered:
Posts: 94
Reply with quote  #16 
Thanks!

I have soldered bare copper wire at the end on each turn to support and keep the spacing between the layers.

In winter my DHW will be supplemented by a Desuperheater in the heat pump, so i will try to get some warm water for my radiant floors in the basement and garage. 


johnd123

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Posts: 15
Reply with quote  #17 
hi chris  great looking job  i have a roof ready for putting a hot water solar panel on  but cant decide whether to go riser or serpentine
i have read that there can be cool spots on the riser setup
have you any ideas o this
john
ChrisJ

Registered:
Posts: 94
Reply with quote  #18 
Thanks John,

I don't believe I am having any cool spots. The height of my risers are pretty short and I used 3/4" manifolds with 1/2" risers.

The main reason I stayed away from the serpentine style is after reading about Scott Davis' large serpentine collector.
He says he has very low flow. He said his riser style CPVC collector works better and is smaller.

Issues I have read about concerning riser type is when the feed and return pipes are in the center feeding 2 sides of a collector. Getting the flow to be even in the 2 halfs can be tricky. Flow, she's a lazy one....Finds the path of least resistance.
ChrisJ

Registered:
Posts: 94
Reply with quote  #19 
I got the first exchanger in, (radiant) it was a bit of a challenge because of room constraints. I am hopeful the DHW exchanger will fit in between the aluminum brace, the end of the tank and the top of the first exchanger.
Solar shed 26.jpg

Here is a picture of the connecting plumbing for the radiant floor.
Solar shed 27.jpg

I have been reusing pipe and components from the original heat pump installation. That heat pump did everything, water to air heat and a/c, water to water radiant and DHW.
That unit died an early death from refrigerant leaks.

The replacement unit is just a Water to Air.

Next is connecting the incoming well water to the second heat exchanger, with options for bypassing the solar so water runs through the desuperheater and I can use the solar just for radiant. 

    

ChrisJ

Registered:
Posts: 94
Reply with quote  #20 
I have the second heat exchanger in and the connecting plumbing.

Solar shed 28.jpg

Solar shed 29.jpg   

Now comes the difficult plumbing. The Desuperheater of my GSHP (Geothermal) connects to an un-powered electric water heater, buffer tank, then to the finish tank which is a heat pump hot water heater (GE GeoSpring).

I know I need closely spaced Tee's on the incoming water line before it goes into the cold inlet of the tank. Problem is the desuperheater uses the cold inlet to draw water up from the tank sending it to the desuperheater, then the warmed water is sent to pipe fitted to the drain in the bottom of the tank. 

I will put the cover back on the solar tank. I had the water up to 120* before I took the cover off to do the exchangers.

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