[Greenbuilding] Solar Hot Water System

[Corwyn]

On Jan 22, 2007, at 13:01, Dusch, Jim E wrote:

> Although I realize a superficial question on this is not necessarily
> helpful, I need some opinions on solar hot water systems.

Not sure what you are worried about.   Your question is fine.

>  The project
> is intended to preheat domestic hot water and radiant floor water prior
> to sending it through an LP fired Takagi Mobius (which currently does
> all the work).  The project is in Maine, where it gets cold for 
> extended
> periods of time.  What preferences/advice do folks have:
>
> Closed-loop or Open-loop?  Drainback?  Integral Collector Storage?
> Others?

Integral collector storage is more useful in warm climates than cold.  
Better to store somewhere warm.

Drainback seems overly dependent on things working correctly, to me.

Open-loop versus closed-loop, I wasn't able to get a Maine contractor 
to agree to open loop due to claimed code issues.  YMMV.

The latest plan for my system (once some money comes in) is as follows 
(just to give you ideas):

Flat panel collectors on the the roof (because they seem easier to 
repair).
Insulated, 250 gallon industrial tote (liquid transport available in 
food grade).  Cheap, bulletproof.
LP gas Aquastar 125BS heater (already installed).

The solar collectors will be on a closed loop antifreeze filled loop.  
 From the collectors, through a heat exchanger (coil of copper tubing) 
in the storage tank, and then through the radiant tubing in the floor, 
and back.  The DHW will go, from the well, through a heat exchanger 
(another copper coil) in the tank and then to the heater.   The potable 
water is twice removed from the antifreeze solution, with both liquids 
having indicators to detect leaks.

Note this system is designed to put supplemental solar heat into the 
basement slab, (all year long probably), and not be the primary heat 
source in the winter.


Thank You Kindly,

Corwyn

-- 
Corwyn
Kermit didn't know the half of it...
http://www.greenfret.com/
corwyn at greenfret.com