[Greenbuilding] [BULK] Solar water heater

[Ian Remmler]

On Thu, Mar 06, 2008 at 05:10:09PM -0600, Lawrence Lile wrote:
> I'm looking at some of the same issues right now, and also looking for
> some recommendations. 
> 
> Drainback systems, I have read, are the most problematic of all solar
> systems, and many companies don't recommend them.  If you have freezing
> issues, go with non-toxic propylene glycol and a heat exchanger. 

Hmmm.  I went to a local talk (Renewable Energy Roundup in
Fredericksburg, TX) about solar hot water, and the presenter
said drainback in his opinion was the best option for our
climate.  He also didn't care for glycol.  I really wish I had
paid more attention, but at the time I didn't think I would have
the space for the tanks in the house.

> Thermosyphon systems are OK if you have exactly the right geometry
> between your collector and the storage tank.  They won't tolerate
> freezing without glycol solution though.  

The one I mentioned has electric backup to prevent freezing.
Not ideal, but, we don't freeze to much here.

-- 
    - Ian.