RV Anti-Freeze for Solar Loop?
Bert Menkveld
it. RV anti-freeze is very readily available (and quite cheap). I've seen
at least one web site state that their RV anti-freeze contains propylene
glycol, which is what I'm after.
Is RV anti-freeze generally a safe bet to use in a solar loop? My local
Home Hardware sells it, but the contained doesn't give any hints about
what's inside.
Any experience/knowledge you can share would be appreciated. Thanks.
Regards,
Bert Menkveld
Duane C. Johnson
Bert;
Bert Menkveld <be...@greentronics.com> wrote:
> I'm assembling a solar hot water heating system, and
> need anti-freeze for it. RV anti-freeze is very readily
> available (and quite cheap).
True, but not as cheap as ethylene glycol antifreeze.
Remember that car antifreeze is mixed 1 to 1 with water.
RV antifreeze is used strait out of the bottle, no mixing.
> I've seen at least one web site state that their RV
> anti-freeze contains propylene glycol, which is what
> I'm after.
Yes. Propylene glycol is non toxic. It is used to winterize
RV water systems. It can be used in places where drinking
water is stored to prevent damage. Of course you are
supposed to flush it out in the spring, but if you forgot
you would not be poisoned.
Heck, propylene glycol is used as a food additive and
sweetener for poultry and meats.
> Is RV anti-freeze generally a safe bet to use in a
> solar loop?
Yes.
The main point in using propylene glycol is when it
is used in a system that can be connected to your
potable water system. If the solar hydronic system
is completely separate then ethylene glycol is the
better product to use.
Ethylene glycol mixes have better thermal properties
at the high temperature end and also transport more
heat per liquid volume than propylene glycol mixes.
(I am reporting what I have read.)
> My local Home Hardware sells it, but the contained
> doesn't give any hints about what's inside.
I bet it does. It says propylene glycol and food
coloring. After all it will be used in potable
water systems.
( The food coloring doesn't have to be listed.)
> Any experience/knowledge you can share would be
> appreciated. Thanks.
> Regards, Bert Menkveld
Have fun! Duane
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Jim Strates
RV's in a home solar heating system? are they the same mix as the prop
glycol I buy from solar workshops in bulk?
Jim
Duane C. Johnson <red...@redrok.com> wrote in message
news:39F1908F...@redrok.com...
Loren Amelang
>
> My question then is....can one use the prop glycol sold in auto stores for
> RV's in a home solar heating system? are they the same mix as the prop
> glycol I buy from solar workshops in bulk?
According to the MSDS for DowFrost (tm) propylene glycol heat
transfer fluid, it is 95% pg, <5% dipotassium phosphate (corrosion
inhibitor, mainly for protection of cast iron boiler systems), and
<5% water. Other brands are quite similar, except they may be
pre-diluted with water to 1/2 or 1/4 of that strength.
Automotive antifreeze contains corrosion inhibitors compatible
with aluminum as well as copper and iron. RV antifreeze probably
has little or no corrosion inhibitor. If your system includes any
iron components, you can easily add appropriate inhibitors. Most
heating system antifreeze companies will sell you their inhibitor
mix separately, as you are supposed to check the concentration
yearly and add more as it is used up.
Note that the big auto antifreeze companies (like Prestone) now
sell propylene glycol as an environmental alternative for auto
cooling system use. My local supermarket has them for about a
dollar more than ethylene glycol. I'd go with that over RV
drinking water antifreeze.
Loren
rlstager
:Ethylene glycol mixes have better thermal properties
:at the high temperature end and also transport more
:heat per liquid volume than propylene glycol mixes.
:(I am reporting what I have read.)
Would that also mean that it takes more energy to get to temperature? Does
it stay in the collector longer to warm up then in the exchanger longer?
Any info would be appriciated.
Ray
georges
>My question then is....can one use the prop glycol sold in auto stores for
>RV's in a home solar heating system?
Yes, straight out of the bottle it is good to-50F, it is already mixed
with the proper amount of water
>are they the same mix as the prop
>glycol I buy from solar workshops in bulk?
Yes, if it is pre mixed and labled good to -50F as above.
--georges
paul bailey
Duane C. Johnson
rlstager <RLSt...@hotmail.com> wrote:
> "Duane C. Johnson" <red...@redrok.com> wrote:
> > Ethylene glycol mixes have better thermal properties
> > at the high temperature end and also transport more
> > heat per liquid volume than propylene glycol mixes.
> > (I am reporting what I have read.)
> Would that also mean that it takes more energy to get
> to temperature? Does it stay in the collector longer
> to warm up then in the exchanger longer?
> Any info would be appriciated.
> Ray
Ethylene glycol mixes have a higher specific heat than
does propylene glycol mixes, I have been told. Not much
more though.
Where ethylene glycol shines is it takes a higher
temperature to break down the molecules than propylene
glycol. This is important if the pumps stop running in
the summer time and the stagnant temperatures get to
high. The breakdown chemicals are acidic.
georges
>
>RV and plumbing anti freeze will sometimes "slush" up long before the freeze
>point but will not freeze solid till it's rated point .
>BEWARE!!!! Paul
So does ethylene glycol for that matter (I speak from experience here:)
--georges
Bloody Viking
Bill & Alice Roosa (roos...@quixnet.net) wrote:
: To answer your question. Yes it does take more heat to raise the
: temperature of ethylene glycol a given amount. That also means that for a
Actually, water takes more BTUs to heat up a degree than ethylene glycol. Same
with propylene glycol, the antifreeze used for RV potable water systems.
A car with too much *ylene glycol in summer will boil over as the engine will
get hotter than with straight water. When I had my last car, I would use more
water for summer ops becuse water transfers heat better than the propylene
glicol I used due to working on the car curbside and being responsible enough
to not want to spill toxic shit. For winter ops, I'd use the 2/3 propylene
glycol water mix, but for summer ops make it mostly water. The winter mix
would not transfer heat well and the car would be prone to boil over. The
pressure cap onboard was 18PSIG.
I did some extensive experimentation with the cooling system aboard the car I
named USS Millennium Falcon. When I first got it, it would boil over a lot. By
the time I got done, it would never boil over. I had boil-over drills aplenty
during my tenure as owner and captain of the USS Millennium Falcon.
--
FOOD FOR THOUGHT: 100 calories are used up in the course of a mile run.
The USDA guidelines for dietary fibre is equal to one ounce of sawdust.
The liver makes the vast majority of the cholesterol in your bloodstream.
dang
dang lable. I've talked to the "Sierra" people and they say the inhibitors
are bad juju. Dowfrost is cheap, doctors are not.
If you are using auto for "for sale" solar systems you should be run out of
town on a rail!
In article <39F1E0FD...@pacific.net>, Loren Amelang <lo...@pacific.net>
wrote:
>Jim Strates wrote:
>>
>> My question then is....can one use the prop glycol sold in auto stores for
>> RV's in a home solar heating system? are they the same mix as the prop
>> glycol I buy from solar workshops in bulk?
>
Loren Amelang
>
> No,no no. Auto antifreeze is toxic even though "environmental". Read the
> dang lable.
Okay, Prestone LowTox Propylene Glycol says "May be harmful if
swallowed" - do you think they would say anything less, even if it
was pure PG? I wouldn't recommend swallowing RV drinking water
system antifreeze, either.
> I've talked to the "Sierra" people and they say the inhibitors
> are bad juju. Dowfrost is cheap, doctors are not.
Dowfrost itself is called "low toxicity", not "non-toxic". In
fact, the 01/08/99 MSDS for Dowfrost says, "The oral LD50 for
female rats is about 20.3 g/kg". So a quart or two should make you
or me seriously sick... "Repeated excessive ingestion may cause
central nervous system effects."
> If you are using auto for "for sale" solar systems you should be run out of
> town on a rail!
If your solar system is set up so there is any chance of your
drinking the antifreeze, you have bigger problems than what kind
of antifreeze it is. My exchanger is double-wall copper with any
leakage obviously visible.
But of course you are right, anyone selling the installation of
automotive or RV antifreeze into DHW systems is risking more than
being run out of town, whether or not there is any real difference
in the toxicity. My personal system is a giant experiment, and a
work-in-progress. When it is "finished" it will get the official
antifreeze, properly installed; until then it is cheaply protected
from destruction.