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Thread: Cost of replacing antifreeze in heating system?

  1. #1
    DIY Junior Member nbulko's Avatar
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    Default Cost of replacing antifreeze in heating system?

    I have a 900 sq. ft. house with a hot water baseboard heating system. Can anyone give me a ballpark figure on how much it would cost to fill the system with antifreeze? I'm in New Jersey, US.

    Thanks for your time.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Just like in a car, you don't use 100% antifreeze, so first, you'd need to know the volume of water in the system. Then, drain out enough water and replace with antifreeze. You need one designed for heatting systems, and you may want to replace or add (if it doesn't have one) a backflow preventer on the supply line...antifreeze is not something you want to have a chance of getting into the potable water. So, it's somewhat hard to say without seeing it.

    The second question, for me anyway, is why do you think you need antifreeze? While there are some systems that may require it, most do not. Using antifreeze in a heating system decreases the heat transfer, making the boiler functionally smaller. SO, keep that in mind, too.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Moderator & Master Plumber hj's Avatar
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    Unless your system was designed for antifreeze, it may not heat adequately, (it does not have the same thermal capacity of plain water), and your expansion tank may be too small because antifreeze has a higher expansion factor. If I remember correctly, 60% antifreeze gives the maximum protection of about 35 degrees below zero F, (which is close to the same degrees in C.).
    Last edited by hj; 10-21-2012 at 02:31 PM.
    Licensed residential and commercial plumber

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    Janitorial Technician nestork's Avatar
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    Nbulko: If you're adding antifreeze to protect your heating system in case your boiler ever breaks down in winter, the better option would be to drain your heating system and refill it after the heating system is repaired. HJ is right in saying that antifreeze doesn't work as well as water when it comes to absorbing and releasing heat.
    Last edited by nestork; 10-22-2012 at 12:43 AM.

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    In the Trades Tom Sawyer's Avatar
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    40% will get you to -16. Though glycol does not transfer heat as well as water the difference can be taken care of by increasing the speed of circulation. In reality though, you probably won't have to make any changes at all. We anti-freeze a good many of thesystems we install, especially radiant heat. Anti-freeze costs me about 18 bucks a gallon.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    Retired Defense Industry Engineer jadnashua's Avatar
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    If you currently have antifreeze in the system, you may want to check the pH of the system and maybe flush it out before refilling.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    In the Trades Tom Sawyer's Avatar
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    Quote Originally Posted by jadnashua View Post
    If you currently have antifreeze in the system, you may want to check the pH of the system and maybe flush it out before refilling.
    Yes, it does go bad.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    Janitorial Technician nestork's Avatar
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    My jug of Prestone II says if your coolant is 50 percent antifreeze and 50 percent water, you're good to minus 34 degrees Farenheit.

    At 70% antifreeze and 30% water, you're good to minus 84 degrees Farenheit.

    Pure ethylene glycol freezes at about plus 10 degrees Farenheit, and that seemed curious to me that the freezing point of a mixture of ethylene glycol and water would be so much lower than the freezing point of either pure ethylene glycol or pure water. So, I did a little snooping and I found this explanation in Wikipedia:

    "Ethylene glycol disrupts hydrogen bonding when dissolved in water. Pure ethylene glycol freezes at about −12 C (10.4 F), but when mixed with water molecules, neither can readily form a solid crystal structure, and therefore the freezing point of the mixture is depressed significantly. The minimum freezing point is observed when the ethylene glycol percent in water is about 70%...."

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

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    Retired Defense Industry Engineer jadnashua's Avatar
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    You should NOT use automotive antifreeze in a residential heating system...use some designed and approved for heating systems.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    In the Trades Tom Sawyer's Avatar
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    Automotive anti-freeze will destroy the seals between boiler sections, circulators etc besides being poisonous.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  11. #11
    Janitorial Technician nestork's Avatar
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    No, I understand that automotive antifreeze is gonna be different from antifreeze you use to winterize a cabin, and that's gonna be different than the antifreeze you might use in a heating system.

    But, I expect they're all gonna behave the same way when it comes to a mixture of the glycol and water freezing at a lower temperature than either component alone. And I figured if I'm wondering why that would be, others would be wondering too.

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    In the Trades Tom Sawyer's Avatar
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    Here; Wiki help


    Ethylene glycol

    Ethylene glycol solutions became available in 1926 and were marketed as "permanent antifreeze" since the higher boiling points provided advantages for summertime use as well as during cold weather. They are used today for a variety of applications, including automobiles, but gradually being replaced by propylene glycol due to its lower toxicity.
    Poisoning
    Main article: Ethylene glycol poisoning

    Ethylene glycol is poisonous to humans and animals,[3] and should be handled carefully and disposed of properly. Its sweet taste can lead to accidental ingestion or allow its deliberate use as a murder weapon.[4][5][6] Ethylene glycol is difficult to detect in the body, and causes symptoms—including intoxication, severe diarrhea, and vomiting—that can be confused with other diseases.[7][4][5][6] Its metabolism produces calcium oxalate, which crystallizes in the brain, heart, lungs, and kidneys, damaging them. If untreated, death by acute kidney failure can result within 72 hours.[7] Some ethylene glycol antifreeze mixtures contain an embittering agent, such as denatonium, to discourage accidental or deliberate consumption.
    Propylene glycol
    Propylene glycol

    Propylene glycol, on the other hand, is considerably less toxic than ethylene glycol and may be labeled as "non-toxic antifreeze". It is used as antifreeze where ethylene glycol would be inappropriate, such as in food-processing systems or in water pipes in homes where incidental ingestion may be possible. As confirmation of its relative non-toxicity, the FDA allows propylene glycol to be added to a large number of processed foods, including ice cream, frozen custard, and baked goods.

    Propylene glycol oxidizes when exposed to air and heat, forming lactic acid.[8][9] If not properly inhibited, this fluid can be very corrosive,[citation needed] so pH buffering agents are often added to propylene glycol, to prevent acidic corrosion of metal components.

    Besides cooling system corrosion, biological fouling also occurs. Once bacterial slime starts to grow, the corrosion rate of the system increases. Maintenance of systems using glycol solution includes regular monitoring of freeze protection, pH, specific gravity, inhibitor level, color, and biological contamination. Propylene glycol should be replaced when it turns a reddish color.[10]
    Glycerol

    Once used for automotive antifreeze, glycerol has the advantage of being non-toxic, withstands relatively high temperatures, and is noncorrosive.

    Like ethylene glycol and propylene glycol, glycerol is a non-ionic kosmotrope that forms strong hydrogen bonds with water molecules, competing with water-water hydrogen bonds. This disrupts the crystal lattice formation of ice unless the temperature is significantly lowered. The minimum freezing point temperature is at about −36 F / −37.8 C corresponding to 60–70% glycerol in water.[11]

    Glycerol was historically used as an antifreeze for automotive applications before being replaced by ethylene glycol, which has a lower freezing point. While the minimum freezing point of a glycerol-water mixture is higher than an ethylene glycol-water mixture, glycerol is not toxic and is being reexamined for use in automotive applications.[12][13] Glycerol is mandated for use as an antifreeze in many sprinkler systems.

    In the laboratory, glycerol is a common component of solvents for enzymatic reagents stored at temperatures below 0 C due to the depression of the freezing temperature of solutions with high concentrations of glycerol. It is also used as a cryoprotectant where the glycerol is dissolved in water to reduce damage by ice crystals to laboratory organisms that are stored in frozen solutions, such as bacteria, nematodes, and mammalian embryos.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  13. #13
    In the trades Dana's Avatar
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    In a NJ climate in a house that has a roof over it, walls with at least some insulation, doors that close, and windows that have glass in them there's no point to putting anti-freeze into a heating system.

    Even if the system went down during the cold-snap it would take days for it to hit the freezing point indoors. In climates like the northern part of the upper midwest or central Maine you could run into issues if the power were down for more than a day during a cold snap. But cold snaps that severe in NJ only occur 1-2x per century, and the power grid is pretty reliable, rarely down for more than a couple of hours in most places, let alone a couple of days.

    A typical 900' home in NJ could be kept above 32F indoors @ 0F outdoor temps (5-15F colder than the 99% design temps for NJ locations) with a single 1500W space heater, assuming the power was up and the system was otherwise broken. (But it would take 3 of them to keep you comfy-cozy when it's 0F outside.) The likelihood of a freeze up is so remote in NJ it isn't worth the price of the anti-freeze, let alone the time to install and test it. If the absolute freak circumstances occurred where a freeze-up risk was real, draining the system would be the right thing to do, but until that actually happens fuggeddaboudit!

    And if the system currently has antifreeze in it, purge the system and go with just plain water.

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    DIY Junior Member compute's Avatar
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    Talking HELP - A word about antifreeze

    I am so confused by all these posts regarding antifreeze. My house is 12 years old and has a Wells McLain furnace with three zones. My plumber designed the system and installed it as the home was being built. But I have had so many freeze up problems over the years (as well as other issues). My biggest problem is a continuing problem with freezeing. My plumber is always telling me that the antifreeze 'leaks' out and is replaced by water from the supply line so there is no longer adequate protection. Two years ago I paid hin nearly $900 to replace the antifreeze. He pumped in 10 to 12 gallons. And today my upstairs is frozen solid. The plumber now say that my anifreeze should be checked every year and replaced every two years because it doesn't last that long. But I read on this forum that some of you are saying I shouldn't need antifreeze at all. I live on the beach in Southern NJ in a large home. I can't believe I am having these problems.

    I am also haveing a continuing problem with zone valve failure. It's not just the Honeywell electronics but it is also the ball valve itself. My plumner just told me that water deposits build up around the valve and cause them to fail. The one zone has had to be replaced 5 times in 12 years.

    Can anyone shed light on what the real problem could be?

    Jim

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    Retired Defense Industry Engineer jadnashua's Avatar
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    If your system is tight, it should retain the antifreeze protection. If you have an autofill valve, and there's even a very small leak somewhere, eventually, the protection level will drop and things could freeze. The antifreeze doesn't lose it's ability to prevent freezing as it 'ages', but it can break down and become caustic. With a leak, the autofill is replacing what's lost with pure (well, it's tapwater) water, constantly, but slowly, raising the freezing point. As an experiment, assuming you have one, turn the autofill off and monitor the system pressure for awhile - it might take a week or more, but if this is the problem, you'll notice the pressure slowly dropping (or faster, if there's a big leak). Even a slow one that's constant will cause the problem.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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