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Expansion tank for antifreeze

Does anyone know if there is a special type of heating expansion tank I'm supposed to use for a system that has antifreeze in it? I Have a system that just burnt through an expansion tank in 6 months. Then antifreeze mixture is about 50% and I have been using Amtrol EX30 tanks.

Amtrol makes a solar and a radiant tank but my supplier doesn't have them in stock and I'd hate to spend the extra money if it isn't needed. I'm reluctant to use the radiant tank as the specs state that the max temp is 200 degrees. Since this is partly a baseboard system, the temps get very close to that? The Solar tank looks like an option as it states it can go to 250 degrees and is rated for glycol.

My second question is. Have I been installing the wrong expansion tank on antifreeze systems all these years? I have always used the Amtrol EX30s and haven't had a problem.

Comments

  • pecmsgpecmsg Posts: 837Member
    Why 50% ?
  • Jamie HallJamie Hall Posts: 10,672Member
    The antifreeze mix shouldn't cause a problem in an Amtrol. The high temperatures might very well. Never good to run something close to its rated maximum...
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • AdvancedplumbingAdvancedplumbing Posts: 16Member
    pecmsg said:

    Why 50% ?

    50% is the maximum allowed for a lot of hydronic components. The freeze protection is still good down to about 0 degrees I believe at 50%.
  • AdvancedplumbingAdvancedplumbing Posts: 16Member

    The antifreeze mix shouldn't cause a problem in an Amtrol. The high temperatures might very well. Never good to run something close to its rated maximum...

    I didn't think it would however, after reading through the documentation on Amtrols website, I found that the standard Amtrol EX tanks do not state they are rated for glycol while the solar and radiant tanks do.

    As far as high temperature goes. This is an oil fired heating system and about half the house is baseboard. I believe the high limit on the aquastat is set to around 180 but these can sometimes overshoot or not be very accurate it my experience. This is why I'm reluctant to put a radiant expansion tank in if I'm going to be running close to the 200 degree max that it is rated for.
  • pecmsgpecmsg Posts: 837Member
    Proplyne glycol is -30* f freeze protection -60*f burst.

    That’s overkill!
  • AdvancedplumbingAdvancedplumbing Posts: 16Member
    pecmsg said:

    Proplyne glycol is -30* f freeze protection -60*f burst.



    That’s overkill!

    I'm using Cryo-tek 100 antifreeze. At 50% it has freeze protection down to 10 degrees and burst protection down to -20 degrees.

  • AdvancedplumbingAdvancedplumbing Posts: 16Member
    Here is a chart of the antifreeze I'm using.

  • pecmsgpecmsg Posts: 837Member
    That’s a lot of protection. One issue with anti freeze is it restricts heat transfer.

    Also why are you running at 200*f
  • AdvancedplumbingAdvancedplumbing Posts: 16Member
    pecmsg said:

    That’s a lot of protection. One issue with anti freeze is it restricts heat transfer.

    Also why are you running at 200*f

    In this particular home there is an apartment over the garage with baseboard heat. The lines feeding the apartment go through and un heated attic to connect to the apartment baseboard. It gets cold here and the temps do drop slightly below zero about once a winter.

    The majority of the main house has radiant in floor heat. This is fed with a temp controlled injection pump from the main system so the temp in the floor heat is much lower. Baseboard requires higher temp. There is also a 80 gallon indirect on the system which requires a higher temp.
  • GroundUpGroundUp Posts: 563Member
    It gets to be -40F here a couple times a year and I've never needed more than 45% even in snowmelt systems- 50% is way overkill in a conditioned space. With that said, what was the failure of the last expansion tank? What is the system pressure and what was the bladder pressure? I wouldn't bet on the glycol playing any role whatsoever and I don't recall ever having seen an Extrol failure on a 180 degree system; some I see are decades old and still kicking. Sounds like either a faulty tank or poor install
  • AdvancedplumbingAdvancedplumbing Posts: 16Member
    GroundUp said:

    It gets to be -40F here a couple times a year and I've never needed more than 45% even in snowmelt systems- 50% is way overkill in a conditioned space. With that said, what was the failure of the last expansion tank? What is the system pressure and what was the bladder pressure? I wouldn't bet on the glycol playing any role whatsoever and I don't recall ever having seen an Extrol failure on a 180 degree system; some I see are decades old and still kicking. Sounds like either a faulty tank or poor install

    Wow -40 is cold. This antifreeze (Hercules Cryotek -100) only has burst protection down to -20 @ 50% dilution. The space is unconditioned as the pipes pretty much go outside before they enter the garage apartment. The old expansion tank was the exact same one. I don't know how old it was but I replaced it while I was doing a bunch of other repairs on the system such as relief valve, spirovent, fill valve, and a few high vents. The pressure in the system is about 15PSI and the tank was pressurized to 15PSI before I installed it. I'm guessing it is either a bad tank or possibly undersized. I have no idea how much radiant is in this house as it is an old farmhouse and you can see anything. I think I'm going to replace it with an EX60 and see what happens.
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