[RE-wrenches] Heat dump or Stagnate?
August Goers
august at luminalt.com
Fri Apr 24 10:38:16 PDT 2009
Darryl -
I've always heard that it isn't good to run glycol in a drainback system.
When the system drains during an overheating condition there is a glycol
residue left in the collectors which cooks and I suppose turns to powder.
Time after time this will decrease system efficiency and possibly degrade
the glycol inhibitors.
Tom Lane, thoughts?
Best,
August
August Goers
Luminalt Energy Corporation
O: 415.564.7652
M: 415.559.1525
F: 650.244.9167
www.luminalt.com
august at luminalt.com
-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Darryl
Thayer
Sent: Thursday, April 23, 2009 4:45 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Heat dump or Stagnate?
Hello
I have done many drain back systems with very little failure. I usually
think it is in the subtleties in the piping/pumping loop when a freeze
occurs. So if you are to drain back, use only water.
I have done many antifreeze systems with ethylene glycol and have had
corrosion in the piping if the antifreeze is not changed. I have had
systems run for more than 10 years before the system has a corrosion leak.
I have never done a antifreeze drain back system. However they seem to be
more popular as time goes on. This is of course a sealed drain back with
anti-freeze instead of water. Then if your piping or pumping loop has
design problems you will not freeze. It would sure be possible to use
nitrogen or argon as a cover gas to prevent oxidation of the anti-freeze and
acidic corrosion of the piping/collectors.
Darryl
--- On Thu, 4/23/09, Troy Harvey <taharvey at heliocentric.org> wrote:
> From: Troy Harvey <taharvey at heliocentric.org>
> Subject: Re: [RE-wrenches] Heat dump or Stagnate?
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Date: Thursday, April 23, 2009, 1:10 PM
> Apparently this is the "modern" design method used
> in many european systems. It scares me too. But from several
> sources, this seems to be considered one of the most
> reliable design methods for closed loop systems (ie. it
> works even without electronic controls working, power
> outages, etc).
>
> Standard glycol. The main point seems to be the design of
> the pipes and collectors need to facilitate collector
> draining from the steam pushing the fluid back into the
> expansion tank, so the collectors empty themselves. Its
> closed loop, but effectively becomes a "pressurized
> drainback" in over heating conditions.
>
> Here is a couple of links:
> http://www.aee-intec.at/0uploads/dateien48.pdf
> http://www.suterconsulting.com/CISBAT.pdf
>
> I'm hoping to find someone with experience with this
> kind of system to overcome my fears
>
> Troy Harvey
> ---------------------
> Heliocentric
> 801-453-9434
> taharvey at heliocentric.org
>
>
> On Apr 23, 2009, at 11:04 AM, Dana wrote:
>
> > I have only seen boiled glycol turn to a cola like
> syrup that had to be
> > purged and removed.
> >
> > What kind of system & glycol is this?
> > Where would you expand that much?
> >
> > Can you provide a link to this paper?
> >
> > We use heat dumps.
> >
> >
> >
> >
> > Dana Orzel
> >
> > Great Solar Works, Inc
> > www.solarwork.com
> > E - dana at solarwork.com
> > V - 970.626.5253
> > F - 970.626.4140
> > C - 970.209.4076
> > "I'd put my money on solar energy. I hope we
> don't have to wait 'til oil and
> > coal run out before we tackle that."
> > -Thomas Edison, in conversation with Henry Ford and
> Harvey Firestone, March
> > 1931
> >
> > -----Original Message-----
> > From: re-wrenches-bounces at lists.re-wrenches.org
> > [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
> Behalf Of Troy Harvey
> > Sent: Thursday, April 23, 2009 10:43 AM
> > To: RE-wrenches
> > Subject: [RE-wrenches] Solar Combi-systems: Heat dump
> or Stagnate?
> >
> > I'm wondering how many of you out there have
> installed medium sized
> > solar hot water systems (6-8 panel) that were designed
> to stagnate
> > during summertime over production as opposed to
> diverting to a heat
> > dump or radiator? The International solar agency has a
> couple of
> > papers that show a properly designed system should be
> able to stagnate
> > in a way that the boiling glycol mix vapors in the
> panels, purge the
> > panels of fluid, turning off the system without
> degrading the glycol.
> >
> > That doesn't seem to be a typical way to design
> systems in the U.S. ,
> > we've usually gone to a heat dump. Does anyone
> have experience with
> > this?
> >
> >
> > Troy Harvey
> > ---------------------
> > Heliocentric
> > 801-453-9434
> > taharvey at heliocentric.org
> >
> >
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