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What ratio propylene glycol for my garage in WI

zole2112
zole2112 Member Posts: 13
I'm installing a radiant system my house. I have 3 zones with 2 attached garages with 1/2" pex 12" spacing in addition to the main house. Both garages were poured over 2" of rigid foam & vapor barrier. How do I determine what min temp do I need to mix my propylene glycol to? Thanks!

Comments

  • hot_rod
    hot_rod Member Posts: 17,467
    It may vary from brand to brand, I would use a reputable brand name fluid to get the best inhibitor package. 35- 40% should be plenty, it really depends on your expected lowest temperature.

    The freeze point is when the fluid forms ice crystals and can no longer be pumped around the loops, but will not burst.

    The burst point is, of course when the fluid freezes solid and can split piping systems.

    With this Dowfrost HD product, 30% gets you burst protection down to -10F. If the garage needs to circulate at below -10F you need to up the %.

    Test the fluid protection level after running the system a few hours. And the circulator pump needs to be sized for the type and % of glycol.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • zole2112
    zole2112 Member Posts: 13
    edited June 30
    Thanks for the info man. I was looking at the Nu-Calgon Freez Kontr'l 95/5. I want assure flow vs burst. I don't know if I need it good to like zero degrees or -10 F, I was looking at the mixing ratios and I don't need to way over design it. I don't have any idea what the temp will get down to under a slab. Like you said I can always tweak it to lower temp protection if need be as long as it still flows anyway.
  • zole2112
    zole2112 Member Posts: 13
    hot_rod said:

    It may vary from brand to brand, I would use a reputable brand name fluid to get the best inhibitor package. 35- 40% should be plenty, it really depends on your expected lowest temperature.

    The freeze point is when the fluid forms ice crystals and can no longer be pumped around the loops, but will not burst.

    The burst point is, of course when the fluid freezes solid and can split piping systems.

    With this Dowfrost HD product, 30% gets you burst protection down to -10F. If the garage needs to circulate at below -10F you need to up the %.

    Test the fluid protection level after running the system a few hours. And the circulator pump needs to be sized for the type and % of glycol.

    The DowFrost HD you mentioned at 44% is good to -10F, cheaper than the NuCalgon, thanks for that!!
  • hot_rod
    hot_rod Member Posts: 17,467
    Once you get to 45- 50%, going over that % doesn't lower the burst, Stay below 50% for pumping and protection reasons, and above 25% for inhibitor strength assurance.

    Picking the right "number" is really up to your comfort level, protection against the arbitrary in many cases. If your attached garage is below -10F, I suspect there are other concerns to address.

    I'd check it every two years for both protection level, and ph. Ph is an indication of when the fluid is
    "wearing out" or has a lot of O2 ingress.

    Dow has been my go to brand for both solar and hydronics. It's probably the base for many other brands also, re-packagers add their specific inhibitor and color.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • zole2112
    zole2112 Member Posts: 13
    hot_rod said:

    Once you get to 45- 50%, going over that % doesn't lower the burst, Stay below 50% for pumping and protection reasons, and above 25% for inhibitor strength assurance.

    Picking the right "number" is really up to your comfort level, protection against the arbitrary in many cases. If your attached garage is below -10F, I suspect there are other concerns to address.

    I'd check it every two years for both protection level, and ph. Ph is an indication of when the fluid is
    "wearing out" or has a lot of O2 ingress.

    Dow has been my go to brand for both solar and hydronics. It's probably the base for many other brands also, re-packagers add their specific inhibitor and color.

    Thank you very much! I needed a gut check on this and your recommendation is greatly appreciated.
  • GroundUp
    GroundUp Member Posts: 1,473
    The temperature rating is of lesser importance than the actual percentage, IMO. Each manufacturer has different temp ratings and they're all over the board with the same percentage. Unless you plan to let the garage freeze purposely for weeks at a time, 30% is adequate. I typically mix 32-33% in MN for garage applications, and 45% for snowmelt applications that I know will be subject to negative temps most of the winter. The 95/5 you mentioned is a little misleading- I bought several 5 gallon jugs last year as I was having trouble getting my usual Fremont or Cryo-Tek, and they were anywhere from 82-92% out of the jug. I had similar inconsistencies with Dow years ago, but have not used any in several years now so that may have changed. At any rate, a refractometer should be used to check actual dilution regardless of brand. Keep it 30-35% and you'll be just fine if the garage will not be intenionally left unheated.
    ZmanCaptainHomerJSmith
  • zole2112
    zole2112 Member Posts: 13
    edited August 24
    GroundUp said:

    The temperature rating is of lesser importance than the actual percentage, IMO. Each manufacturer has different temp ratings and they're all over the board with the same percentage. Unless you plan to let the garage freeze purposely for weeks at a time, 30% is adequate. I typically mix 32-33% in MN for garage applications, and 45% for snowmelt applications that I know will be subject to negative temps most of the winter. The 95/5 you mentioned is a little misleading- I bought several 5 gallon jugs last year as I was having trouble getting my usual Fremont or Cryo-Tek, and they were anywhere from 82-92% out of the jug. I had similar inconsistencies with Dow years ago, but have not used any in several years now so that may have changed. At any rate, a refractometer should be used to check actual dilution regardless of brand. Keep it 30-35% and you'll be just fine if the garage will not be intenionally left unheated.

    That sounds great, I would have the same conditions here in WI. We will not ever let it freeze, our plan is to heat the main garage to about 50 and keep it there through the winter (of course my wife may decide it isn't warm enough lol. Our back garage "kitchen" (my wife calls it our dirty kitchen) will be at 60 all winter. I really appreciate the information you provided as well as all that others provided as well.
  • HomerJSmith
    HomerJSmith Member Posts: 1,798
    edited August 24
    Remember, pumping requirements change between H2O and a antifreeze mix. You can lose up to 12% in pumping power with antifreeze. Less pumping power, less flow.
    zole2112
  • zole2112
    zole2112 Member Posts: 13
    edited August 25

    Remember, pumping requirements change between H2O and a antifreeze mix. You can lose up to 12% in pumping power with antifreeze. Less pumping power, less flow.

    I'm glad you mentioned that, weird that I considered the difference for the pump to fill the system but wasn't thinking about it when sizing my system pump (I'm using zone valves). From what I see it looks closer to 7% for 30% Propylene Glycol solution but I'm still studying it as I see you mentioned 12%, is that what you see in practice or theoretical?

    I was planning to use the Grundfos UPS 15-58 FC, I have about 2600 ft of 1/2" pex in 3 zones - Garage 1 - 3 loops (50 F), Garage 2 - 1 loop (60 F), Main House area - 5 loops (65 F).

    I need to do some additional investigation and calculations.
  • hot_rod
    hot_rod Member Posts: 17,467
    Glycol is a bit harder to pump and a bit lower heat transfer compared to water.
    Generally increasing the pump speed if you have a multispeed circ will handle it.

    Once you decide on a brand of glycol, use the tables on the bucket or literature to get the protection level you want. Not all glycols are blended the same.

    Typically the more expensive brands are better blends, and better inhibitor packages.

    There is a freeze and burst temperature. Freeze is where you can no longer pump it, but pipes will not burst, also called slush point.
    Then burst is where it freezes solid.

    So if you do not want to heat at extreme low temperature, you could use a lower percentage.

    Get a ph meter or test strips and check a sample every year or two. A refractometer is good for checking % and freeze protection. Find them on Amazon for not much $$.

    More about fluids here, and the page on glyclols.

    https://www.pmmag.com/articles/88030-fluid-factors-br-john-siegenthaler-pe
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    zole2112
  • zole2112
    zole2112 Member Posts: 13
    hot_rod said:

    Glycol is a bit harder to pump and a bit lower heat transfer compared to water.
    Generally increasing the pump speed if you have a multispeed circ will handle it.

    Once you decide on a brand of glycol, use the tables on the bucket or literature to get the protection level you want. Not all glycols are blended the same.

    Typically the more expensive brands are better blends, and better inhibitor packages.

    There is a freeze and burst temperature. Freeze is where you can no longer pump it, but pipes will not burst, also called slush point.
    Then burst is where it freezes solid.

    So if you do not want to heat at extreme low temperature, you could use a lower percentage.

    Get a ph meter or test strips and check a sample every year or two. A refractometer is good for checking % and freeze protection. Find them on Amazon for not much $$.

    More about fluids here, and the page on glyclols.

    https://www.pmmag.com/articles/88030-fluid-factors-br-john-siegenthaler-pe

    Cool, I will definitely be getting a refractometer. I have a Brix Refractometer I use for brewing beer so I'm excited to get one to monitor my freeze protection!
  • hot_rod
    hot_rod Member Posts: 17,467
    For a deep dive into to PG glycol.

    I think a lot of glycol suppliers start out with Dow glycol and add their own inhibitor packages and blend pre-mix solutions.
    A lot of products you eat have Dow food grade glycols in them, a petroleum product :) Technical grades used as antifreeze and it gets squirted on aircraft in the winter, deicers and anti-icers.

    https://www.dow.com/content/dam/dcc/documents/en-us/app-tech-guide/180/180-01286-01-engineering-and-operating-guide-for-dowfrost-and-dowfrost-hd.pdf?iframe=true
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    zole2112
  • mattmia2
    mattmia2 Member Posts: 6,590
    So here is a question I have. Should I sequence the boiler and boiler loop before the glycol loop when using antifreeze and a heat exchanger with water in the boiler, in other words get the boiler side heating and circulating before I start circulating the antifreeze solution which might be much colder than the freezing point of water?
  • zole2112
    zole2112 Member Posts: 13
    hot_rod said:

    For a deep dive into to PG glycol.

    I think a lot of glycol suppliers start out with Dow glycol and add their own inhibitor packages and blend pre-mix solutions.
    A lot of products you eat have Dow food grade glycols in them, a petroleum product :) Technical grades used as antifreeze and it gets squirted on aircraft in the winter, deicers and anti-icers.

    https://www.dow.com/content/dam/dcc/documents/en-us/app-tech-guide/180/180-01286-01-engineering-and-operating-guide-for-dowfrost-and-dowfrost-hd.pdf?iframe=true

    Hey Hot Rod, you had mentioned in another post to run a hydronic cleaner through the system before filling. This was in response to a dude using a sump pump to fill, which sounds like a good way for me to fill my system. At first I was thinking you were just referring to running the cleaner through the sump pump portion but were you referring to the entire system? It seems like it would be a good idea to run it through the entire system to remove any oils etc that were in the components.
  • hot_rod
    hot_rod Member Posts: 17,467
    These spray cans make it easy to squirt in a cleaner. I think a can does 35 gallons of system fluid. Save the conditioner to boost the glycol in a few years if needed.
    Check the ph every year or two, when it drops into the 8's squirt some conditioner to boost the protection of the glycol. Th oxygen scavengers get used up over time in glycols. Keep the ph in the 10, or whatever the glycol bucket suggests.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • zole2112
    zole2112 Member Posts: 13
    I'm getting close to putting my system together, I am pretty much set but I do have a question which may be dumb lol. So my system will be closed, my question is around the piping. I run my outlet pipe from my boiler to a tee where I connect it to the return pipe off of 1 side of the tee and then to the zones from the other side of the tee. Why doesn't the heated fluid equally flow into the return pipe and the feed pipe, or is it supposed to do that?
  • hot_rod
    hot_rod Member Posts: 17,467
    zole2112 said:

    I'm getting close to putting my system together, I am pretty much set but I do have a question which may be dumb lol. So my system will be closed, my question is around the piping. I run my outlet pipe from my boiler to a tee where I connect it to the return pipe off of 1 side of the tee and then to the zones from the other side of the tee. Why doesn't the heated fluid equally flow into the return pipe and the feed pipe, or is it supposed to do that?

    Maybe draw a pic of what you mean.
    You want to pipe a loop, out of the boiler, through the zone and back. An air sep, expansion tank and some isolation valves
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • zole2112
    zole2112 Member Posts: 13
    like this pic, it's my buddy's son's set up that he did. There are 2 tees connected with 1 going to the input and 1 going to the return
  • zole2112
    zole2112 Member Posts: 13
    I would think I just need to loop out of the boiler through the zones and back to the return essentially, closed system so I don't need any mixing. I am just unsure on why you would need to connect the lines like that, I've seen it elsewhere in pics too.
  • hot_rod
    hot_rod Member Posts: 17,467
    what brand and model boiler are you using?

    That pic shows primary secondary piping often used on mod con boilers. Called closely spaced tees.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    zole2112
  • zole2112
    zole2112 Member Posts: 13
    Oh, ok that makes sense then. I have a Bosch Greenstar ZBR-42. I read it was called closely spaced tees. I wanted to make sure I wasn't missing something. Thank you!!
  • JakeCK
    JakeCK Member Posts: 1,045
    If heating the garage to 50 all winter long, is glycol even needed at all, or can it be treated the same as the rest of the house if continuously occupied?
  • WMno57
    WMno57 Member Posts: 554
    edited November 15
    @JakeCK , Garages tend to not be insulated as well, sometimes have concrete aprons that extend under the overhead door, and are hard to drain in the event of a boiler failure or power outage. Pre failure the house is 68 and garage is 50, so less time to address the failure. Garage doors are large openings that occasionally get left open, or break and don't close. Burst tubes in the slab can't be repaired.
    That said I would like to build a small one bay shop with a heated slab - all water. Will have at least 4 inches of foam under and at slab edges, a way to gravity drain, compressed air to blow out the slab loops, and some form of redundant heat.
    JakeCK
  • hot_rod
    hot_rod Member Posts: 17,467
    Slabs have quite a bit of flywheel effect. I suspect a slab at 50f may take a day or two for tubes to start freezing. I would keep the loop back from the door a foot or more also.

    My shop is around 900 sq ft, single zone. I used a 3 way valve and it circulates constantly. I’m not sure what temperature it would take to freeze water moving at 3-4 feet per second. An interesting test to perform.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JakeCK
  • zole2112
    zole2112 Member Posts: 13
    I think if you had constant circulation you may not have issues but there is much higher risk associated if that flow is interrupted or even just restricted to a degree (I have no idea to what level where freezing would begin) or if your water temperature out of your boiler dropped for some reason. With the glycol you have a much wider operating range and the risk of freezing is pretty much eliminated.
    WMno57