Drainback vs. Closed Loop Circulators [RE-wrenches]

Jay Peltz, Peltz Power jay at asis.com
Sat May 20 07:51:37 PDT 2006


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todd et all,

I would like to point out that the pros/cons of the tube collectors  
does depend on where you live.

If you live in say Florida with high temps then tube collectors don't  
make heat sense.

If you live in a cloudy and cold area, then they make more sense.

Also I think that the modularity of the tube systems might be  
important for easy expansion.

So there are many ways to look at which is the best type of collector  
of which I have pointed out only a few.

thanks,
jay

peltz power
On May 20, 2006, at 5:09 AM, Bill Loesch, Saint Louis Solar wrote:

>
>
> Todd et al,
>
> Please don't confuse the issue with heat transfer between the two  
> systems.
> First, you need to decide if you want guaranteed freeze protection.  
> If the
> answer is yes, the only way I know how to provide _guaranteed_ freeze
> protection is through the use of antifreeze. Both types of systems  
> can use
> antifreeze. Both types of systems then will have similar heat transfer
> through their heat exchanger.
>
> To trust freeze protection of your thousands of dollar system to the
> electric differential temperature control and/or sensors to not  
> fail at a
> critical time is not (for me) prudent or cost justified. Who pays  
> for the
> damaged system when a freeze does occur? The control manufacturer  
> with whom
> you've spent less than two hundred dollars with? I doubt it.
>
> While the freeze protection prevents a dramatic failure, a much more
> insidious risk is that of hard water in any of the systems. Hard  
> water over
> time, will produce a gradual loss of heat transfer which is likely  
> to go
> unnoticed. Unfortunately the scale acts as wonderful insulation.  
> So, make
> sure your water supply is appropriate for long term health of the SDHW
> system, whatever system you ultimately choose.
>
> I'm surprised Tom didn't point out that the tubular collectors  
> don't shed
> snow and frost as well as the flat plates.
>
> Respectfully,
>
> Bill Loesch
> Solar 1 - Saint Louis Solar
> 314 631 1094
>
>
> Message text written by INTERNET:RE-wrenches at topica.com
>>>
>> I have seen bad experiences with evacuated tube collectors. They are
>> fragile and the performance gain is not worth it unless you are  
>> trying to
>
>> make steam. Flat plate collectors are heavy and take 2 to 3 people to
> lift
>> them on the roof, but they last forever.
>>
>> Drainbacks are more efficient in terms of heat transfer, but the  
>> energy
>> for pumping is MUCH higher than a closed glycol loop. It is  
>> probably a
>> toss up as to which is better. What do others think about this?
>>
>> Todd
>> <
>
>
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