[RE-wrenches] solar hot water nighttime recirc

[Conrad Geyser]

We use chrome oxide collectors exclusively.  

 

What I'm getting at is that the system will satisfactorily self regulate.
Just from all the combined parasitic losses, a typical flat plate system
will top out around 180F max.tank temp. in an average summer climate even
without nighttime heat dumping.   Night time heat dumping is nice way to
bring that number down more in a case of limited occupancy / overproduction.
Here in the Northeast, more often than not, residences have basement
dehumidifiers running all summer.  If that is the case and there isn't
significant AC being used, we tend to use a basement heat loop for the
excess heat.  Again, no numbers, but any thermal load that can help against
a giant electrical dehumidification one is a gain.

 

An evacuated tube system needs more sophisticated top heat regulation. 

 

Conrad

Cotuit Solar  

 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of
mark at hurshtown.com
Sent: Friday, December 18, 2009 10:26 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] solar hot water nighttime recirc

 

I was once told that the best collector used black chrome plated on bright
nickel.  

This combination absorbs heat well, with the advantage of not letting the
heat back out.  

Sort of a thermal "diode" of sorts.

I have no data, but I believe "good" collectors radiate less than they
collect.

 

Mark

-------- Original Message --------
Subject: Re: [RE-wrenches] solar hot water nighttime recirc
From: "Carl Emerson" <freepower at freepower.co.nz>
Date: Fri, December 18, 2009 10:04 pm
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>

Hi there gang,

 

Just to say that IMHO solar thermal panels will radiate quite a bit less
than they collect, someone must have some data on this ??

 

Have a great Christmas.

 

Carl Emerson

Free Power Ltd.

Web   www.freepower.co.nz

 


  _____  


From:re-wrenches-bounces at lists.re-wrenches.org [
<mailto:re-wrenches-bounces at lists.re-wrenches.org>
mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Conrad Geyser
Sent: 18 December 2009 5:42 p.m.
To: nponzio at buildingenergyus.com; 'RE-wrenches'
Subject: Re: [RE-wrenches] solar hot water nighttime recirc

 

Nicholas,

 

You can certainly do that.  Most newer controllers have a "vacation"
function that will provide this.  Another method is to put in a bypass to
the check valve that you can open and the system will naturally reverse
thermo siphon at night.  Not much in the way of calculations other than the
collectors reradiate as effectively as they collect.

 

Conrad

Cotuit Solar

 


  _____  


From:re-wrenches-bounces at lists.re-wrenches.org [
<mailto:re-wrenches-bounces at lists.re-wrenches.org>
mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Nicholas
Ponzio
Sent: Wednesday, December 16, 2009 10:54 PM
To: RE-wrenches
Subject: [RE-wrenches] solar hot water nighttime recirc

 

Apologies if this has already been discussed here.

One heat diversion method I hear suggested often is recirculating through
the collectors (flatplate) at night. Are there any data, calculations or
anecdotal evidence on the effectiveness of this approach? That is, can I
really radiate as much energy back to a dark sky as I collect during the
day?

Thanks for any feedback.



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