1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)

Why not RV propylene glycol in a boiler?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by danjayh, Oct 26, 2012.

  1. danjayh

    danjayh New Member

    Joined:
    Aug 23, 2012
    Messages:
    67
    I was in Menard's today and I saw the RV stuff for $3/gallon. Any reason this can't be used in a boiler? It's soooooo much more affordable than any actual 'boiler' propylene glycol that I've seen. Pictures of the actual product attached.

    I'm actually planning on running treated water this year regardless ... this is purely for curiosity's sake.

    Attached Files:

    Helpful Sponsor Ads!





  2. TheMightyMoe

    TheMightyMoe Minister of Fire

    Joined:
    Aug 2, 2012
    Messages:
    552
    Loc:
    Fairbanks, Alaska.
    I feel your pain =/ Needed 150$ in glycol for my system, I know people that have spent 500$+ for their radiant systems.

    Would need the product MSDS to know... I'm guessing its the inhibitors.
  3. danjayh

    danjayh New Member

    Joined:
    Aug 23, 2012
    Messages:
    67

    My boiler is outside (CB Maxim), so I'd have to get ~33 gallons if I wanted freeze protection down to 0f. That would cost me more like $700 from what I've seen. I think I found the MSDS for the menards stuff, and I think it has ethanol in it, even though it's not listed on the bottle ... so that's probably how they can sell it so cheap :(
  4. TheMightyMoe

    TheMightyMoe Minister of Fire

    Joined:
    Aug 2, 2012
    Messages:
    552
    Loc:
    Fairbanks, Alaska.
    Hmmm... You should look around, I am running 60/40 propylene, I mixed it myself. I believe the pure propylene was around 15$ a gallon. How much is it per gallon for you? *_*
  5. Woodsrover

    Woodsrover Member

    Joined:
    Oct 15, 2012
    Messages:
    111
    Loc:
    Northwest Connecticut
    I work in a bodyshop. We get rid of 300-400 gallons of antifreeze a year that comes out of cars with damaged radiators or cars where we remove the radiators for repairs. We don't reuse coolant. I'm going to install a boiler in my barn that will require antifreeze and I'm going to simply filter this used stuff and use it.

    Show up to your local bodyshop with a tank and a pump and they'll give you all the antifreeze you want.
  6. Bob Rohr

    Bob Rohr Minister of Fire

    Joined:
    Jan 9, 2008
    Messages:
    798
    Loc:
    SW Missouri
    The glycol used for closed loop hydronic systems has special buffer components. Both PG and EG are used in boilers, EG is a bit more toxic, but lower cost. EG is commonly used in larger commercial systems where it cannot come in contact with domestic water.

    Either PG or EG can be recycled. They allow it to settle out run it thru multiple filters, finally an RO then they re-buffer and add color back into it. Many automotive suppliers sell re-pourposed glycol. PG and EG can be mixed as some cars now come with PG antifreeze. When it is drained it goes into the same recycle barrels at the Lube Shops.

    Automotive glycols contain silicates and will sludge up hydronic pumps, boilers, valves, etc after time. Not a wise idea to use automotive glycol in hydronics. It will reduce heat transfer as soon as it is added and starts coating your boiler with silicate gel.

    Hydronic glycols contain many buffers, which is why they cost more. Special glycols have been produced to work in systems with aluminum and these contain 20 or more ingredients.

    Hydronic and solar glycols are buffered for PH, hardness, they include oxygen scavangers, disperants and film providers. Dow adds a patented additive they protects the fluid if it is mixed with hard water instaed of the required DI or DM de-mineralized water.

    RV antifreeze is pretty much a food grade PG with some coloring, not much in it to protect you hydronic investment.

    Read the label carefully, some RV antifreeze is menthol based, and flammable. Glycol is non-flammable in solution up to 80%.

    Heat pumps systems sometimes use methnol, but in a very weak solution. Any air elimination devise should be vented outside on methanol or ethanol systems.

    There are some hydronic and solar glycols now on the market that are corn, or bio based instead of oil based. These tend to be a bit less expensive. Dynalene, and Susterra are two names for bio based.

    Many antifreeze products have been tried over the years, the search goes on for a lower cost, safe, non corrosive fluid. Potassium based fluids are making a comeback for GEO applications, silicone based, even some oil based fluids that look a lot like ATF.

    An off grid friend of mine bought cheap vodka, blended it and uses it for his solar system antifreeze in No. Cal :) Stay thirsty, and safe my friend.

    hr
  7. heaterman

    heaterman Minister of Fire

    Joined:
    Oct 16, 2007
    Messages:
    3,097
    Loc:
    Falmouth, Michigan
    Good way to lose a lot of components in your system, void any warranty on your boiler and cost yourself far more than the difference in antifreeze cost.

    I know from experience that CB will not warranty any perforation/corrosion in their boilers unless you can show documentation of their specific brand of chemical treatment only with sales receipts and proof of testing.
  8. Robby

    Robby Member

    Joined:
    Nov 9, 2008
    Messages:
    87
    Loc:
    Priddis, AB, Canada
    I use treated water in heating(boiler) system, but needed freeze protection in solar system. After a bit of thought used Prestone Low Tox (pet safe) automotive antifreeze mixed at 40%. There is no ethylene glycol in it and I don,t see much difference between metals in auto and solar. So far good, 4 years, will be adding to collector this summer and will just top up.
  9. Ramblin Mo

    Ramblin Mo New Member

    Joined:
    Nov 3, 2012
    Messages:
    4
    I ran across this site when looking for proper anti-freeze to use in a solar water heater. I found a product at Home Depot that seemed to fit the bill for my use. My solar coil heater is designed to heat my green house thermal storage water barrels and does not come in contact with any water used for consumption.

    It is a little off topic I suppose as the original discussion was for an anti-freeze for boilers, but maybe someone will find it useful. It runs about $3.00 a gallon at my store.

    Uni-Gard -50 Uni-Proof Anti-Freeze is a Propylene Glycol based anti-freeze and heat transfer fluid. Premixed to provide -50 degree F burst protection when used full strength.

    • DKP additive protects most metals from corrosion
    • HUD-approved for solar systems
    • Ideal for a variety of industrial uses
    • Safe, Odorless, Non-Staining
  10. Bob Rohr

    Bob Rohr Minister of Fire

    Joined:
    Jan 9, 2008
    Messages:
    798
    Loc:
    SW Missouri
    If it is a RV antifreeze it is not formulated for hydronic or solar. Solar stagnation temperatures can exceed 340°F. A solar specific fluid will have components that allow it to operate at that temperature and still protect you system, but t5hat adds a bit of cost to the fluid.. Keep an eye on the ph, that will tell you if the fluid is breaking down.

    Attached Files:

  11. jebatty

    jebatty Minister of Fire

    Joined:
    Jan 1, 2008
    Messages:
    4,491
    Loc:
    Northern MN
    Apart from the additive issue, I could not endorse the use of EG (ethylene glycol) antifreeze. It is toxic and deadly, tastes sweet so any spill or leakage found by an animal or child will be lapped up and likely cause a horrible death through attack on the nervous system, kidneys and heart. My old OWB, in place when I bought the property, had an EG solution. A slow leak resulted in a small puddle on the basement floor, lapped up by a pet cat, and followed by an agonizing death over a 3-day period. After two years this remains vivid and painful in my memory. Don't use EG -- risk to children, pets and wild animals is great.
  12. Ramblin Mo

    Ramblin Mo New Member

    Joined:
    Nov 3, 2012
    Messages:
    4
    Sorry to hear about your cat. I have four that own me and I would be devastated. This stuff is PG/Alcohol.

    Uni-Gard -50 Uni-Proof Anti-Freeze is a Propylene Glycol based (And alchohol) anti-freeze and heat transfer fluid.

    Solar stagnation in my system could happen with my system if I had a pump failure I suppose, but I don't think that I will see temps over 160 F. If the sun is shining, the pump should be running. I have made my panels modular so that they can be folded up and stored away in spring summer and fall. I just need the supplemental heat in my greenhouse over the winter.
  13. tom in maine

    tom in maine Minister of Fire

    Joined:
    Apr 4, 2008
    Messages:
    735
    Loc:
    Searsport, Maine
    Not to spoil anyone's fun. Or maybe to preserve it:
    Vodka is basically ethanol which can evaporate from a heating system if given the chance.
    Never a good thing, especially if you are relying on it as antifreeze.

    Keep the ethanol/vodka/moonshine for adult beverages. Use the proper propylene glycol. Sometimes you just have to pay. (or shop for a good deal on the right stuff!)

    Always felt that all the heat exchangers we make would make great stills....
  14. Ramblin Mo

    Ramblin Mo New Member

    Joined:
    Nov 3, 2012
    Messages:
    4
    Makes me wonder now about the description on the HomeDepot site.

    DKP additive protects most metals from corrosion
    HUD-approved for solar systems (I wasn't aware that HUD had anything to do with approving products)
    Ideal for a variety of industrial uses
    Safe, Odorless, Non-Staining


    If I was making a system for a domestic water supply, I would definitely use the safest anti-freeze I could find.
  15. heaterman

    heaterman Minister of Fire

    Joined:
    Oct 16, 2007
    Messages:
    3,097
    Loc:
    Falmouth, Michigan
    Bottom line is this.

    You are buying the antifreeze to protect many $$ worth of equipment and piping in your system. Why take a chance on something that is not recommended for the use intended?

    As to the variables presented by the solar portion of your system...Pumps do quit. Temperatures can spike rapidly during stagnation even on a 0* day in the winter. One or two times up to 300* in your collectors and any antifreeze other than something made specifically for those temps will be nearly worthless.

    Do it right, do it once.
  16. Ramblin Mo

    Ramblin Mo New Member

    Joined:
    Nov 3, 2012
    Messages:
    4
    You all talked me into it.
    Hercules Cryo-Tek 100 -
    Tracked down at Lowe's for a reasonable price. Virgin propylene glycol premixed.
  17. heaterman

    heaterman Minister of Fire

    Joined:
    Oct 16, 2007
    Messages:
    3,097
    Loc:
    Falmouth, Michigan
    You are a wise and prudent fellow. I don't care what the rest here say about you. ;)
  18. kennyl70

    kennyl70 New Member

    Joined:
    Oct 28, 2012
    Messages:
    46
    Loc:
    Missouri
    Heatmor delaer said i have to run the inhibator they provide... but... i can run the rv antifreeze if i feel a need to. not see why i would ever have to but, they just said dont run alot due to it eats heat.
  19. willyswagon

    willyswagon Burning Hunk

    Joined:
    Mar 18, 2012
    Messages:
    218
    Loc:
    PEI, Canada
    As my father(life long plumber) says, because if they wanted you to use that in a boiler, it would be labeled
    "RV and Boiler Antifreeze ", it's not labeled like that because that is not the intended purpose.:(
    Then the lecture about inhibitors and alike start.<>
  20. willyswagon

    willyswagon Burning Hunk

    Joined:
    Mar 18, 2012
    Messages:
    218
    Loc:
    PEI, Canada

    As you can see by my signature, I couldn' agree more!!

Share This Page