I been reading  about using propylene for freeze protection on this site and others.   I can buy a 50/50 mix at my local tractor supply store for $4.59 a gal. But then I read about a 50/50 mix for $170 for five gal from a solar dealer on line. What is the difference in the two.  This would be for a closed loop system using copper flat plate solar  panels and pex in a radiant floor.

No one has an opinion on Propylene gycol??
After reading some it sounds like Sierra brand automotive antifreeze might work. Its propylene glycol with additives to help with corrosion. Any thoughts???

Here`s what I`m using, $15 a gallon. Doug

http://kscdirect.com/item/HER+35281/HERCULES+CHEMICAL+CO.%252CINC_1GL+CRYO-TEK+-100+ANIT+FREEZE%250A

Spec Sheet #S00041
February 2007
cryo-tekTM
ANTI-FREEZE for heating and cooling systems
DESCRIPTION
A blend of virgin (not recycled) propylene glycol and high purity Triple Protection additives, formulated for
use in closed loop hydronic heating and cooling systems. Cryo-tek can also be used in radiant tube
heating systems, most solar heating systems and geothermal loops. Hercules' exclusive Triple Protection
formula stabilizes pH to prevent acid corrosion, chelates hard water minerals and inhibits the formation of
scale and sediment. These components work together to keep the system clean and operating efficiently
by eliminating system deposits, improving heat transfer and minimizing wear to moving parts and seals.
Cryo-tek is compatible with PEX and elastomeric radiant tubing, commonly used materials for seals and
bushings and provides corrosion protection for cast iron, steel, copper, brass and solder. Cryo-tek has
not been tested for use in systems containing CPVC plastic. Standard cryo-tek products should not be
used in systems containing aluminum and operating above 160F/71C. Cryo-tek -100/AL is available for
aluminum systems. Cryo-tek should not be used in systems with galvanized piping as the zinc coating
will be dissolved. Cryo-tek is a 94-98% efficient heat transfer solution in most application dilutions. It has
cr
a lower freeze point and higher boiling point than water and is non-flammable, odorless, non-toxic, non-
irritating and compatible with Hercules boiler stop leaks and heating system cleaner products.
=========================================================
I got the following from this web page,
http://www.hydratech.co.uk/article1.html, from an article in /"Process
Cooling & Equipment USA, November 2000" /which is talking about cooling
systems but it should apply just as well to heating systems.

*Avoid Uninhibited Glycols*
Uninhibited or plain glycols provide freeze and burst protection at a
relatively low initial cost. But, freeze protection is not the only
consideration in choosing fluids. Corrosion presents an ongoing threat
to water-based system components. If left unchecked, heat, oxygen,
chloride, sulfates, metallic impurities and other contaminants can
increase the rate of corrosion in a heat transfer system. Corrosion can
lead to unscheduled shutdowns, high maintenance expenses and reduced
system life.

Because they lack corrosion inhibitors, plain glycols can actually
increase the threat of corrosion. Glycols produce organic acids as they
degrade, especially when heated. If left in solution, these acids will
lower the fluid's pH. With no corrosion inhibitors to buffer these acids
and protect the metals in the system, the corrosion rate of a plain
ethylene or propylene glycol solution can be greater than plain water -
a highly corrosive fluid in its own right.

The industrial inhibitor packages needed are specially formulated to
help prevent corrosion in two ways. First, they treat the surfaces of
the metal to make them less susceptible to corrosion. Second, the
inhibitors buffer the organic acids formed as a result of glycol
oxidation to keep the fluid from becoming acidic. Thus, inhibited
glycol-based heat transfer fluids provide corrosion protection without
reducing a system's heat transfer efficiency by fouling.

These two replies came from Homepower. I`m sticking with the good stuff,
which I`ve found for $15 a gallon. Doug
-----------------------------

> At 9:20 AM -0500 6/4/06, Doug Kalmer wrote:
>
>> I have a PV pumped solar hot water system on my house that uses
>> propylene
>> glycol as an antifreeze. How often should it be changed? Several
>> people on
>> solar online groups claim that I don`t need to buy expensive propylene
>> glycol made just for solar, but can use inexpensive RV antifreeze
>> available
>> locally. The RV antifreeze is propylene glycol, and has anticorrosion
>> additives, and says it`s safe for copper. What do you think? Thanks,
>> Doug
Richard Perez wrote:

> Hello Doug
>
> I'd go with the solar version even though it's more expensive. I
> change our glycol every two or three years. The solar version is
> designed to withstand high temperatures while the RV antifreeze is
> not. There are several grades of solar glycol, so get the one with the
> highest temp rating. When the glycol gets very hot it turns acetic and
> eats pipes and pumps.
>
> I'm cc:ing our solar thermal guy Chuck Marken on this to see if he has
> more info or a second opinion.
>
> Richard

Hi Doug,

I use litmus paper to test propylene glycol solutions. It just takes a
drop or two on the 1/4" strip to get a good reading. I use paper that
changes color at a pH between 6 and 8. Concentrated propylene glycol has
a pH above 9 and is about 8 or above when mixed 50/50 with water. When
the pH of the solution falls below 7 - it needs changing. Since litmus
paper is not an exact reading, I recommend changing it below pH 7.4. If
everything is operating OK, propylene glycol solutions can easily go ten
years or more before changing them. I test a few systems each month and
most, by far, are above pH 7.6. It is a good idea to test the solution
every year or two.

As Richard states, heat is the enemy of glycol solutions and excessive
heat will turn the solution various shades of brown. Dark brown is
usually bad news and a good indication that the glycol needs changing.
The more expensive propylene glycol concentrates like Dowfrost (TM),
have buffers (aluminum hydroxide is one) that prevent the glycol from
turning acetic. All these glycols I am familiar with are called
inhibited because of the buffers. The buffers in different propylene
glycols are rated from about 280 degrees F to 325 degrees F (Dowfrost
HD). I don't know if all RV antrifeezes have the necessary buffers for
protection since they are not normally subjected to elevated
temperatures. If they aren't advertised as inhibited, you should check
with the manufacturer to insure buffers are included.

I get my litmus paper from a local chemical supply store - enough for
five to ten years at my usage level costs about $12 - for anyone testing
their solution once a year, a roll will easily last a lifetime.

Cheers,

Chuck

----- Original Message -----
From: "Ken Sheinkopf"
To: "Doug Kalmer"
Sent: Tuesday, June 06, 2006 10:36 AM
Subject: Re: proplyene glycol


Iasked John Harrison of the Florida Solar Energy
Center about this. He has been involved in research,
installation and testing of solar water heating
equipment for more than 20 years. John also does a lot
of work with the Solar Rating & Certification Corp
(SRCC). Here is his response:


This is a tough question for many reasons.

1. He should use propylene glycol that has been
specified for his solar system. Problem is, we do not
know if this is an SRCC or FSEC approved system. If
it was, I could tell you what p. glycol was specified.

2. Do not know if the system has a single or double
wall heat exchanger. If double wall, then non-food
grade p. glycol could be used. Actually, any glycol
could then be used so long as the heat exchanger is
vented to the atmosphere.

If single wall, he would have to go with an approved
propylene glycol. SRCC has allowed the use of
Dowfrost "R" propylene glycol (also labeled Dowfrost
Regular.).

3. As far as replacing with anything available, that
is what I suspect happens with a lot of these systems.
Maintenance people just go to the hardware store and
buy any p. glycol they have available without
considering whether it is suitable for the system or
occupant. I have heard that in the past some
companies even went and got some ethylene glycol (used
in radiators) for the solar system. E. glycol is
toxic for sure and if used in a single wall hat
exchanger, they (whoever drank the solution) could be
in for some trouble if leaks within the heat exchanger
occurred. These days, most companies stay with
propylene glycol for safety reasons.

So, in the end, and not knowing much about the system
(single or double wall heat exchanger, whether the
double wall heat exchanger is vented, etc.) I would
recommend that he use Dowfrost "R" (Regular) propylene
glycol. It's FDA approved - food grade - and has no
problems with copper.

Having said that, does he really need to replace the
existing glycol? He should test the glycol with a pH
kit to determine if it is still maintaining it's
chemical properties. He can always get a solar
installer to check this.


--- Doug Kalmer wrote:

>
> I have a PV pumped solar hot water system on my
> house that uses propylene
> glycol as an antifreeze. How often should it be
> changed? Several people on
> solar online groups claim that I don`t need to buy
> expensive propylene
> glycol made just for solar, but can use inexpensive
> RV antifreeze available
> locally. The RV antifreeze is propylene glycol, and
> has anticorrosion
> additives, and says it`s safe for copper. What do
> you think? Thanks, Doug
>
>


Ken Sheinkopf
sheinkopf@...

Researching propylene glycol for solar collector use on the web I found
information stating that automotive glycols are not suitable for solar
systems-
"Glycol based automotive anti-freeze is different because it is inhibited
with silicates. This type of inhibitor is excellent for protection of
aluminum at high temperatures and where an agitated environment is present.
In a HVAC system where circulation is low and copper and steel are present,
it can gel causing loss of heat transfer and system plugging."

So I got recommendations from a solar installer, sent out inquiries, and
found the best deal on the correctly inhibited propylene glycol from
http://www.dynalene.com/ -

"The smallest container that we sell the Dynalene PG in is 5 gallon pails.
The price is $65.00 per pail and this material can ship via UPS or FedEx."

Bernie Selvey
p: 610-262-9686 x111
f: 610-262-7437
e: BenardS@...

I always makes sense to use the manufacturer's specified product. If it costs more we can attribute this to value added i.e. you get what you pay for. Bernie makes the case exactly but it pays to reiterate the deadly nature of ethylene glycol use for most automotive anti-freeze solutions. There is simply no place for it in residential HVAC applications. Note further that ethylene glycol (automotive anti-freeze) tastes sweet and will shut down the kidneys of a small animal or child in matter of hours.

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001778/#adam_000774.disease.complicationsa

The proper mix of anti-freeze is determined by the job at hand. Anti-freeze should be tested for pH every year but it would be the very rare case that would necessitate its replacement every three years or 10 for that matter, unless it is being "cooked". For high temperature solar systems a high propylene glycol purpose-made would be the ticket...but you likely won't find it at tractor supply.

You can obtain the pet friendly propylene glycol from NAPA auto parts or most any respectable auto store.

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=SIR091_0006406839

Make sure you read the MSDS and make sure that it is compatable with the materials in the system you intend to use it. Use the MSDS to compare the ingredients between the cheap and expensive brands to ascertain any difference and value.

"Glycol based automotive anti-freeze is different because it is inhibited
with silicates. This type of inhibitor is excellent for protection of
aluminum at high temperatures and where an agitated environment is present.
In a HVAC system where circulation is low and copper and steel are present,
it can gel causing loss of heat transfer and system plugging."

You really have to pay attention here.

Once you have seen several thousand dollars worth of boiler corroded or plugged up or otherwise destroyed and hand the hapless owner a bill for a grand or more (if you are lucky enough to get a warranty HX) you start to appreciate the free advice given with every boiler made as it concerns compatible antifreeze. I have never seen a boiler, PEX or other hydronic component manufacturer's reference for NAPA.

Right, like I stated you need to read the MSDS and make sure that it is compatable with the materials in the system you intend to use it. Don't put much stock in what "experts" on the Internet recommend. Much of the automative anti-freeze sold today is both silicate and phosphate free and will state so on the bottle. If it can be used in a aluminum/copper/steel automotive cooling systems for 10 years/100,000 miles between change-outs, it will work fine in your hydronic radiant floor heating system. In addition to the aforementioned NAPA Sierra, here are some more:

http://www.amsoil.com/shop/by-product/other-products/antifreeze/propylene-glycol-antifreeze-and-engine-coolant/

http://engineice.com/prev/faq.html

All the Japanese automobile dealerships have this too. Do you own research, try it yourself, inspect it annually, and report your results...

So, what does the Material Data Safety Sheet have to do with the compatibility of any automotive anti-freeze with any hydronic heating system. In particular, who will pay for the boiler heat exchanger when it is denied for lack of factory specified additives?
Get the pertinent information and get back to us.

Proper glycol for solar is made for the very high temps. DowFrost or Tyfocor (available from Viessmann or Stiebel Eltron, and others) are the two best ones. Hood chemicals also makes one. DO NOT USE RV stuff or car antifreeze. Yes the proper stuff is more expensive but it is made so that after the glycol steams out in high temp panels during stagnation periods, the inhibitors will go back into suspension with the glycol after it condenses. Others won't do this and the system may suffer.

MSDS sheet only deals with toxicology.

Yes, a technician may use a MSDS for toxicity and health effects. An engineer will also use it to consider physical data (in this case, freezing and boiling points) and reactivity when considering its use for a specific engineering design or application.

http://en.wikipedia.org/wiki/Material_safety_data_sheet

So here's the DowFrost data:

http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0040/0901b80380040bcb.pdf?filepath=heattrans/pdfs/noreg/180-01314.pdf&fromPage=GetDoc

If you compare DowFrost against the aforementioned Amsoil at an equal volumetric mix of water and propylene glycol, you will see that the freezing and boiling points for BOTH products are identical. For example, at 50% the freezing point is -28 deg F and the boiling point is 222 deg F for BOTH. There is nothing magic about the DowFrost.

Anyhow, you requested that I get back to you. I hope you find this informative and helpful.

And where will you find the pH on an MSDS?

We can't even get licensed technicians to use the specified glycol and you want the layman to go to NAPA...seriously.

As you indicated, many states don’t even require a HVAC license. Even for the states that do require a HVAC license, the licensing requirements are pretty minimal (a couple years of experience, pass an exam, and perhaps be bonded and insured in the more stringent states). One does not even need a HS degree to become a HVAC contractor. So I would agree that the average technician may NOT be competent to exercise a “or equivalent” chemical clause and they should explicitly follow engineering and manufacturer instructions…which hopefully they are at least capable of reading and fully understanding. However, there are many DIY homeowners who are very competent and comfortable with undertaking a HVAC project associated with their own home…or even completely building their own home…and state law allows this too.

So YES, as long as a “layman” follows all state building code and inspection requirements and is only performing the work on their own home, they will likely be BOTH successful and happy with their results, and we fully support their DIY efforts in this regard. I would also agree that there are likely “layman” that are far less competent than an experienced or licensed HVAC technician, and they would do well to completely stay away from power tools and chemicals.

Since our company consists of licensed professional engineers and construction contractors, we are obligated to seal and sign our engineering designs. We are also obligated to provide maintenance instructions and offer a warranty for our in state construction services. We include a pH kit with our maintenance instructions and we recommend that the hydronic fluid be tested annually. We have found that most heating system problems are initially caused by some clueless HVAC technician installing dissimilar metal fittings so as to cause galvanic corrosion or by inadequate long-term maintenance.

And just be 100% clear, we have the highest respect for good HVAC technicians. They are just hard to find... A good technician is worth their weight in gold in my book, and can usually handle the actual mechanical installation aspects better than me.

I never said there was anything magic about DowFrost, only that it has a long track record dealing with solar applications. It is NOT just the freezing and boiling points that are important with solar and any GOOD solar guy knows this. The additives are not just any boiler additives. They must maintain they structure after repeated changes in state and not degrade at 150C+.

Almost anyone can plumb in a solar system but it takes a lot of time to really understand how to get the most heat out of them and what makes them last. 95% of techs and engineers won't put in that time because it is not profitable.

Tyfocor is a better product anyway.......

We use Tyfocor

Posted By tandemsforus on 01 Nov 2010 10:53 PM
I been reading  about using propylene for freeze protection on this site and others.   I can buy a 50/50 mix at my local tractor supply store for $4.59 a gal. But then I read about a 50/50 mix for $170 for five gal from a solar dealer on line. What is the difference in the two.  This would be for a closed loop system using copper flat plate solar  panels and pex in a radiant floor.

I can get 5 gallons of Pure Propylene glycol for 75$... Contact a company called Chemical specialties in Colorado. I agree with one of the later posters that said you don't need to run AL safe glycol in you system. Copper can handle just about any thing but AL safe adds some odd stuff that gums up the works. I run a mix of prop-glycol based on my needs, often you don't need to go lower than 30/70 Water to glycol. As even if the fluid will freeze at one point its burst point is much much lower. The other thing I add is a water wetting agent to the mix. it gets rid of the millions of small bubbles that form on the walls of metal while heating and increase heat transfer eff