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Antifreeze instructions for Oil Hot Water system

Does anything know of a good "how to" instruction manual for draining water from and adding antifreeze to an oil hot water heaing system? System has copper tubing to radiators, leading from 2" black pipe feed and return lines. Also need to know just when antifreeze will require replacement, pros and cons of this vs. other pipe protection methods, etc. (House is 225 years old; radiator pipes go through outside walls and freeze periodically even when furnace is running.)



  • George_10
    George_10 Member Posts: 580
    Contact Drew at The Noble Company

    His number is 1-800-678-6625 ext 108

    His company is one of the players in the glycol market and he may access to such info.
  • hr
    hr Member Posts: 6,106
    Fairly simple

    first make sure you do not have leaks anywhere, even small seeps around fittings. Then check the quality of the water in the system and the water you will use to refill the system. Stay avay from hard or high TDS water. a local water treatment company can test this for you.

    Then add a good hydronic system cleaner into your system. You will need to calculate the system volume to know how much cleaner is needed. I like the Rhomar products for this.

    I like to let the cleaner circulate and run at temperature through all the zones for a few days at least.

    Then the system needs to be drained and flushed with clean water. check the drain water after the cleaner has wotrked. I like to capture the flush out water in a couple white plastic buckets to see exactly what comes out, rust, scale, etc.

    Then you need to add the required amount of hydronic anti freeze mixed with GOOD blend water. I purchase deminerlized water for this. DO NOT use hard water to blend glycols or you will use up the inhibitors from the get go.

    You will need to have some isolation and purge valves to assure you get all the cleaner flushed out and the glycols pumped in.

    Run the system for a few days and check the glycol for freeze rate and ph levels.

    Glycol does have a habit of leaking out of questionable joints. make sure you address this, or else you will have to drain and save all that glycol.

    With large diameter pipes like that you may need 30 gallons or more. May be cheaper to buy a drum quanity. Dow, possibly Nobel, and other suppliers will premix drum quantities and save that hassle for you. Just pump from the drum to the system without mixing hearaches. They use RO water at the factory to blend to your freeze requirements. Generally 35-45% is adequate if you use a GOOD brand glycol. You'll need a contractor with a transfer pump and some hydronic knowledge to assure all goes as planned :)

    And you will want to check the ph and freeze rate yearly to prevent any problems.

    hot rod

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