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OT: question for HVAC folks who know hot water heat systems

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  • OT: question for HVAC folks who know hot water heat systems

    One of the problems with radiator systems is that if for some reason the heating fails in very cold weather, and stays out for too long, you have a risk of freezing of the radiators, which breaks the whole system and gets quite expensive. Not only does the heating system need totally replaced, you also have water damage all over.

    I have a house in another city several hundred miles away. I cannot drop everything and drive there to drain the system in case of a power failure etc, that might last long enough to risk a freeze.

    So, what would be wrong with getting sufficient antifreeze (probably the less toxic propylene glycol) into the radiator system to protect it against freezing? It seems that would be effective, and should not cause issues.
    2730

    Keep eye on ball.
    Hashim Khan

    Everything not impossible is compulsory

  • #2
    Did some searching and found this: https://inspectapedia.com/heat/Boiler_Antifreeze.php

    Sounds like the biggest problem to watch for is corrosion. Id also wonder about reducing the lifespan of the systems heating elements

    Comment


    • #3
      Good info, I had not found that. Thanks.
      2730

      Keep eye on ball.
      Hashim Khan

      Everything not impossible is compulsory

      Comment


      • #4
        Jerry, when I lived in England many years ago that type of central heating was universal, pumping water around a closed circuit. It was universally understood that the water needed additives to prevent the type of damage you rightly fear, and there were many anti-freeze/anti-corrosion products readily available specifically for that purpose.
        Here in New Zealand that type of heating is practically unknown, so I can't help you from here, but surely that sort of product is available in the US of A?

        Comment


        • #5
          I remember as a young buck changing a lot of frozen cast iron radiators on income property. Hard work indeed. Antifreeze would and is a good idea. Now calculate the cost. It's the reason why it isn't done so much. The heating capacity is a bit less with antifreeze mixture. It must be checked for chemical break down periodically. I did use it on an infloor pex system I installed, but that was far fewer gallons than you would need. Still if you add up all the heating and plumbing that would need to be replaced, it would make sense. Work the numbers and let us know if it's feasible. If you do make sure you use a nontoxic antifreeze.

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          • #6
            Originally posted by J Tiers View Post

            So, what would be wrong with getting sufficient antifreeze (probably the less toxic propylene glycol) into the radiator system to protect it against freezing? It seems that would be effective, and should not cause issues.

            Yup. I was half way down your post and antifreeze came to mind.

            I think its a good call. JR

            Comment


            • #7
              It is a good choice. Using the propylene glycol is good for safety (nontoxic). There is food grade antifreeze, but I think that may be a bit much. There are additives for corrosion prevention and Ph correction. Do a bit of research and you will be good. Search "glycol heat exchanger" for more info.
              Robin

              Happily working on my second million Gave up on the first

              Comment


              • #8
                Originally posted by J Tiers View Post
                Good info, I had not found that. Thanks.
                Use of the term "Hydronic" is far more commonly used in the trade than "hot water". If you search for hydronic heat freeze protection you will find plenty of reading and products to review.

                I worked on hydronic heat systems for many years until they lost popularity and most good HVAC supply houses have both water treatments and freeze protection in stock. I especially remember working on one in a church (in upstate NYS) where they set the temperature WAY back during the week and the lines in the attic area froze during a exceptional cold spell. The return line in that attic was 2 or 2-1/2" and quite long, froze solid, it was quite a challenge to thaw it while minimizing further damage. So yes, hydronic heat systems do indeed freeze at times although it is very rare.

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                • #9
                  We use stuff called ferrinox over here,, can be inserted via a radiator, your thermostat should be a frost stat, ie a frost setting, easily installed, Honeywell do one, plus I’d add a magnetic separator if the system is old, goes on the return line in front of the pump
                  mark

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                  • #10
                    Be sure to have a double Check Valve (2) on your water supply system. Some community water systems regulations are very restrictive on
                    counter-flow possibilities. Hydronic heating itself makes "black water" ( no air/oxygen) in the boiler system and they do not want it in the city water system

                    Rich
                    Green Bay, WI

                    Comment


                    • #11
                      Originally posted by Sparky_NY View Post

                      Use of the term "Hydronic" is far more commonly used in the trade than "hot water". ..................
                      Yeah, I know of that term, but as you guessed, did not use it in the search.

                      2730

                      Keep eye on ball.
                      Hashim Khan

                      Everything not impossible is compulsory

                      Comment


                      • #12
                        Be sure to have a double Check Valve (2) on your water supply system. Some community water systems regulations are very restrictive on
                        counter-flow possibilities. Hydronic heating itself makes "black water" ( no air/oxygen) in the boiler system and they do not want it in the city water system
                        They are referred to as backflow preventers

                        Comment


                        • #13
                          Glycol is common in in floor radiant heating systems here in Alaska. Especially if there is exposure to ambient conditions such as a section of concrete slab in front of a hangar door, heated sidewalks and driveways. I have a glycol filled system in my hangar heating system. Glycol systems require more maintenance, are roughly 18% less efficient at transferring heat and if not treated with anti-corrosives will degrade the entire system. Plus polypropylene glycol is very expensive and will find leaks in the system that water will not find, major pain in the ass.

                          Jerry, consider a freeze protection system for the heating system. Such as a battery/inverter backup for the boiler only. I have a manual system in my house. If the power goes out and is expected to stay out I turnoff the power switch at my boiler (effectively isolating it from the power grid) and plug in an extension cord from my 1800 watt generator. With your skills you could make yours automatic. Me thinks it would be less expensive and if you're into smart technology you could keep an eye on the system.

                          Comment


                          • #14
                            Is yer house unoccupied or a rental? Seems to me having a neighbor or tenant who could open the drain valve in case of a deep winter power outage would be the simplest solution. Or nc5a proposal of battery backup. A battery could run a circulator for quite some time.

                            After Sandy we ran ours off the generator till we got power back. I had rigged the boiler with a cord that plugged into an outlet so I could simply plug it into an extension from the generator without all the issues of energizing the disconnected house grid. The area was lucky it was a warm late fall, had there been an early freeze there would have been so much plumbing destroyed.
                            Location: Jersey City NJ USA

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                            • #15
                              Originally posted by gellfex View Post
                              Is yer house unoccupied or a rental? Seems to me having a neighbor or tenant who could open the drain valve in case of a deep winter power outage would be the simplest solution. Or nc5a proposal of battery backup. A battery could run a circulator for quite some time.

                              After Sandy we ran ours off the generator till we got power back. I had rigged the boiler with a cord that plugged into an outlet so I could simply plug it into an extension from the generator without all the issues of energizing the disconnected house grid. The area was lucky it was a warm late fall, had there been an early freeze there would have been so much plumbing destroyed.
                              Jerry did say it had the old cast iron radiators so its a pretty old system. Many of those old systems did not even have a circulator pump, they were gravity flow systems. If there is no pump, all that is needed to keep the heat on is a tiny ac source just to operate the thermostat / gas valve, a amp or two. If there is a circulator pump and its the new minature type they are pretty low power and wouldn't take much to provide backup power for.

                              Antifreeze in the system, if used, is lost if the system has to be drained down for any repairs. Antifreeze is quite expensive to put in even once.

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