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Indirect radiant heating scaling issue suggestions needed.

I am trying to resolve scaling issue that is plaguing my check valves. Unfortunately I can't provide you with the hardness of my water because I haven't had it tested recently, but plan to in the next couple of weeks. Evidently the calcium content must be higher then I original thought. Since the system heats the radiant floor and provides for the domestic hot water the check valves are failing open due to the calcium scaling getting trapped in the gate opening thus allowing the cold water supply to bypass the normal flow circuit and temper/blend with the domestic hot water even though I'm descaling the water heater on a regular basis.

My issue is I can't install a salt water based water softener as we have our own well and septic system so we don't want to be adding all the salt discharge to the aquifer for our water supply. I did install a Watts one flow plus TAC filter and recently added a scalesweeper electronic system to the hot water loop to see if it would further help. I realize that because the system is recirculating continuously through the system and doesn't refresh the water in the circuit unless domestic hot water is used compounds my issue of scaling as we don't see these issue at the faucets. So I'm curious to see if anyone has any other suggestions that might alleviate my issue.

I am posting pictures so you can analyze my flow pattern of my system. Thank you in advance for looking and any input you may have for me. Also I will be replacing the spring check valve with a vertical swing gate as I believe the gate will less likely be able to get trapped open as easily as it does in a spring check valve by scale. Also note I am considering replacing the horizontal swing gate check valve with a Y stainer in hopes of filter out the scale before it reaches the check valve.

Thanks again, Robb




Comments

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 2,682
    edited February 21
    I'm impressed with the quality of your work and the thought you've put into it.

    I have very little experience with dealing with high mineral content water, but you might consider installing a serviceable check valve while you are finding a solution:

    https://www.caleffi.com/usa/en-us/catalogue/serviceable-flow-check-valve-low-lead-na51200
    Often wrong, never in doubt.
    Indirectsystem
  • Youngplumber
    Youngplumber Member Posts: 495
    edited February 21
    What in the sharkbite am I looking at? Lol. I'm just messing with you.

    I think it's a balance of headaches either a better filtration system which requires maintenance and more money or maintenance the serviceable check valves as mentioned above. 
  • Indirectsystem
    Indirectsystem Member Posts: 6

    What in the sharkbite am I looking at? Lol. I'm just messing with you.

    I think it's a balance of headaches either a better filtration system which requires maintenance and more money or maintenance the serviceable check valves as mentioned above. 

    Thank you for your input. Yeah I got lazy and through in the shark bites to make disassemble easier. Although I like to idea of the check valve utilizing unions which would make it way easier for servicing I can do the same thing to the swing check valve I'm planning on using to replace the spring on with.

    Thanks for the suggestions, still hoping someone else has the same issue and found yet other alternatives as well.

    Youngplumber
  • Jamie Hall
    Jamie Hall Member Posts: 15,350
    Um... err... do I get the impression that this is an open system, that the radiant floors share water with the domestic hot water? If so, you are going to have scaling problems. You can't help it (in addition to other health concerns). The problem, of course, is that every time you use the domestic hot water you introduce a nice fresh batch of scaling minerals into the heating system, so it should be no surprise that they build up.
    Br. Jamie, osb
    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
  • Youngplumber
    Youngplumber Member Posts: 495
    @Jamie Hall I had the same thought. But I thought the heat exchanger in the pic implied it closed, at least the space heating portion. I guess I should have asked that. 
  • Indirectsystem
    Indirectsystem Member Posts: 6

    Um... err... do I get the impression that this is an open system, that the radiant floors share water with the domestic hot water? If so, you are going to have scaling problems. You can't help it (in addition to other health concerns). The problem, of course, is that every time you use the domestic hot water you introduce a nice fresh batch of scaling minerals into the heating system, so it should be no surprise that they build up.

    Jamie,

    Thank you for responding! Technically it is not an open loop system it is a indirect, Minnesota doesn't allow for open loop. The floor hydronic is heated by a heat exchanger. So if I understand your explanation that when the hot water in the exchanger loop has cool fresh water introduced to it, it will shock the calcium and cause it to bind and form crystals??? I see how this could be but then I would think that I'd be see excessive mineral particulate in the supply screen of the tankless heater but I don't. Generally the issue happens as the hot water exits the tankless since it immediate that I know if the check valve has particulate in it I'm quick to descale and flush the system.
  • Jamie Hall
    Jamie Hall Member Posts: 15,350
    It would be nice if hardness caused scaling worked that way... it doesn't quite. What happens is that as the water temperature increases, the solubility of the dissolved Calcium and Carbonate ion pair drops -- dramatically -- and it will precipitate out (yes, as a crystalline sold -- but not free floating crystals) on pretty much anything handy, forming a hard mineral coating. Like your check valves.

    In a closed loop like your heating system (thank you for clarifying that!) once the Calcium and Carbonate present in the initial water charge have precipitated out, that's the end of it. But in a flow through system -- like domestic hot water -- more Calcium Carbonate is added every time you run the water -- and more scale forms.

    It is problematic with hard water and a septic system -- the last thing you want in that septic system is the saline backwash from a water softener! -- and I'm glad you appreciate that. In such a situation, I think that the best approach is to systematically flush at least the water heater and associated valves on a regular basis.
    Br. Jamie, osb
    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
  • Indirectsystem
    Indirectsystem Member Posts: 6
    edited February 22


    It is problematic with hard water and a septic system -- the last thing you want in that septic system is the saline backwash from a water softener! -- and I'm glad you appreciate that. In such a situation, I think that the best approach is to systematically flush at least the water heater and associated valves on a regular basis.

    Thanks Jamie,
    This is what I was afraid of, and it truly is a shame as we have such great clean tasting water apart from the evidently high calcium count.

    For now do you think I should go with replacing the spring check valve with a swing gate or just add unions to each end for easier servicing then add a Y-strainer before it and possibly one on the inlet to the Takagi for further protection? I'll set a regime of descaling every 3 months and possible every month during the winter heating season. I was hoping to get by with just one on-demand, in hindsight I wish I had opted for two or coughed up the 3K and just went with a combi-boiler as the system loses approximately 15% of it's efficiency in the heater exchange (150F into exchanger and it's 130F into floor radiant) . I could look at air-injection for mineral removal but at that cost I'm probably better off adding a second on-demand and have one dedicated for the floor radiant and one for the domestic hot water.

    Thanks again for your quick response and thank you @Youngplumber for your efforts as well.
    Have a great day!
    Robb
  • Canucker
    Canucker Member Posts: 669
    @Indirectsystem I think adding the unions to make servicing easier and a descaling regime is the way to go. With hard water I don't see any way around it if you can't soften it.
    You can have it good, fast or cheap. Pick two
  • Jamie Hall
    Jamie Hall Member Posts: 15,350
    Do add the unions. They make life so much easier...

    And if you decide to add another unit for the floor, make it a proper mod/con boiler, not a tankless or combi. They are far less subject to problems with hard water.
    Br. Jamie, osb
    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
  • HomerJSmith
    HomerJSmith Member Posts: 1,196
    You would be well to have an indirect H/W tank and have the boiler and radiant separated from the well supply with good water in them. You are always going to have problems even if you descale the boiler. The Honeywell proportional mixing valve is going to calcify and stop mixing as well as the boiler Heat exchanger and flat plate heat exchanger.
  • Derheatmeister
    Derheatmeister Member Posts: 997
    I am guessing that electronic the Scale sweeper does't work ? It would be nice to know how much Calcium you have!
    Hanna sells a checker that will not break the bank https://www.google.com/aclk?sa=L&ai=DChcSEwiY37G9ioDvAhXMn7MKHSHuD8MYABAGGgJxbg&ae=2&sig=AOD64_0xhTpUrDe9zdhoxLYx1Z_ZUNoAjw&ctype=5&q=&ved=2ahUKEwjwmqi9ioDvAhUHCc0KHeDtAtQQ9aACegQIAxBC&adurl=
    Have you considered Using a Scale transformer that will keep the Calcium in suspension as long as the temperature does not exceed 80 C .
  • Indirectsystem
    Indirectsystem Member Posts: 6

    I am guessing that electronic the Scale sweeper does't work ? It would be nice to know how much Calcium you have!
    Hanna sells a checker that will not break the bank https://www.google.com/aclk?sa=L&ai=DChcSEwiY37G9ioDvAhXMn7MKHSHuD8MYABAGGgJxbg&ae=2&sig=AOD64_0xhTpUrDe9zdhoxLYx1Z_ZUNoAjw&ctype=5&q=&ved=2ahUKEwjwmqi9ioDvAhUHCc0KHeDtAtQQ9aACegQIAxBC&adurl=
    Have you considered Using a Scale transformer that will keep the Calcium in suspension as long as the temperature does not exceed 80 C .

    So the scale sweeper was just added recently and has only been in place or 2 weeks so the jury is still out on that and I'm not holding my breath. I actually added it in desperation to aid my Watts OneFlow+ Combination Whole House Salt-Free Anti-Scale and Water Filtration System for up to 10 gpm (37.5 lpm) which uses template-assisted crystallization (TAC) technology that is suppose to physically bind hardness ions together to prevent them from forming scale. It utilizes a replaceable cartridge which is to last for 2 years, however I may need to replace it yearly as my hardness level is probably on the high side of the filters effectiveness.

    I will order up the hardness checker you recommended and see where I'm at and report back when I have this info, this tester is cheaper then I can have the water tested for at a lab, so the cost is negligible. Unfortunately I will be on the road for the next two months as I work in nuclear power generation and it's refuel outage season so it will be some time before I can provide that info. In nuclear plants we don't have this issue because the core/boiler utilizes demon water (demineralized) it's just not so good for home domestic hot water. lol

    So I'm pretty fed up with this system by en-large even more so with the radiant company who designed it and fabricated the loop for me, (you would think a company who's business it is to design and build these systems would know how to properly solder fittings but since I've had to repair 2 that failed I guess it's not a requirement, LOL!!!) and I'm wondering how to estimate the size of combo boiler I will need as to get the most efficiency from it. I'm look into a Bosch Greenstar Combi 151 - 134K BTU - 95.0% AFUE - Combi Gas Boiler - Direct Vent, but I'm not sure if this maybe overkill based on my requirements. I have a 1500 square ft slab grade townhome with 2 baths, on average there is only 2 occupants taking 2 showers back to back, 2X a day with the occasional guest or two every other month. I live in Minnesota so were a cold region during the winter and we generally like to keep the temp around 73F during the heating months and the whole slab is setup as one zone. I am also considering adding a 50k hydronic hanging heater to my garage which would be zoned so I'd want to account for this in sizing my unit.

    Thanks again for the input and have a great day!
    Robb

  • WMno57
    WMno57 Member Posts: 185
    Robb,

    I think you are making this too complicated. If I were in your shoes (actually I am, I have rural hard water), I would get a cheap standalone water heater to heat your domestic hot water. When the cheap water heater dies an early death you replace it. Having the water heater separate from the boiler that heats your house is a good thing.

    I don't understand your aversion to water softeners. A new basic water softener uses minimal salt, and can be plumbed to soften hot water only. That isn't going to harm your septic system. Millions of rural homes are doing this. You alone, are not going to save the aquifer.
    bucksnort
  • Jamie Hall
    Jamie Hall Member Posts: 15,350
    There are any number of magnetic magic contraptions out there. Some of them are said to reduce hardness in water. Some are said to reduce scaling in hot water. Some of them are said to improve the gasoline mileage of you car or truck. Some of them... You can also get them for your arthritis, psoriasis, and I have no idea what else.

    They all have two things in common. First, they don't work in any kind of valid testing, and second they cost money.

    Before someone screams, magnetic separators do have a valid and necessary place: if you have iron or steel piping, and somewhat corrosive water, you will get magnetite in the water. Magnetic separators do a wonderful job at trapping that -- before it gets into such things as ECM pumps and ruins them. There are also magnetic oil monitoring (usually drain) plugs which are useful to alert you to excess wear in engines. Again, well worth the effort -- an engine seizing up can ruin your whole day.

    If you have excessively hard water, and you can't live with it, you must remove the Calcium and Magnesium ions. The best way to do this, for domestic hot water, is a nice plain vanilla ion exchange water softener. They work fine. The amount of brine they produce is minimal. It's best if they are only for the hot water, as that is a much smaller usage.

    If you have a hot water heating system -- baseboards, radiators, radiant floors, coils in air handlers, it doesn't matter -- it's worth the money (which isn't that much) to use demineralized water in it. Since the usage after the initial fill should be zero, not a big deal.
    Br. Jamie, osb
    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
    WMno57
  • WMno57
    WMno57 Member Posts: 185


    In nuclear plants we don't have this issue because the core/boiler utilizes demon water (demineralized)

    Watch out for Demons in the Nuke Biz.
    https://en.wikipedia.org/wiki/Demon_core
  • Indirectsystem
    Indirectsystem Member Posts: 6
    edited February 27
    WMno57 said:


    In nuclear plants we don't have this issue because the core/boiler utilizes demon water (demineralized)

    Watch out for Demons in the Nuke Biz.
    https://en.wikipedia.org/wiki/Demon_core
    LOL, nothing like that in the plants and I should know, I'm the guy manipulating the nuclear fuel. (now that's a scary thought! :s LOL)

    There are any number of magnetic magic contraptions out there. Some of them are said to reduce hardness in water. Some are said to reduce scaling in hot water. Some of them are said to improve the gasoline mileage of you car or truck. Some of them... You can also get them for your arthritis, psoriasis, and I have no idea what else.

    They all have two things in common. First, they don't work in any kind of valid testing, and second they cost money.

    Before someone screams, magnetic separators do have a valid and necessary place: if you have iron or steel piping, and somewhat corrosive water, you will get magnetite in the water. Magnetic separators do a wonderful job at trapping that -- before it gets into such things as ECM pumps and ruins them. There are also magnetic oil monitoring (usually drain) plugs which are useful to alert you to excess wear in engines. Again, well worth the effort -- an engine seizing up can ruin your whole day.

    If you have excessively hard water, and you can't live with it, you must remove the Calcium and Magnesium ions. The best way to do this, for domestic hot water, is a nice plain vanilla ion exchange water softener. They work fine. The amount of brine they produce is minimal. It's best if they are only for the hot water, as that is a much smaller usage.

    If you have a hot water heating system -- baseboards, radiators, radiant floors, coils in air handlers, it doesn't matter -- it's worth the money (which isn't that much) to use demineralized water in it. Since the usage after the initial fill should be zero, not a big deal.

    @WMno57

    Yeah, for the most part this is true but it's a little more involved and complex. Actually electro magnetic resonance has been employed industrially since the turn of the nineteenth century as a mean of filtration and scale reduction. The physics principle for electrostatic filtering works like this. Instead of causing the dissolved ions to come together and form non-adherent scale, a specific surface charge/frequency is imposed on the ions to repel them from each other rather than attract to each other. Thus the two like ions (positive and negative, or cations and anions, respectively) needed to form scale are repelled from each other and become unable to initiate a scale-forming reaction. The problem is these are finely tuned systems that emit a calculated precise magnetic frequency which based on the amount of particulate that is flowing thru the system.

    With that said I was, yes a fool to buy the scale sweeper as the frequency it emits is probably not operating at the correct resonance for my situation thus the $99 dollars could have been spent else where and why most consumer based magnetic products don't work as advertised.

    Jamie, thank you for opening my eyes to this comment "It's best if (water softener) they are only for the hot water, as that is a much smaller usage." The HOA does not allow owners to operate water softeners as a means of protecting the septic system and our well water supply, so I will need to convince them (HOA board) the amount of discharge water that would be going into the septic system and aquifer would be negligible even if every townhouse unit were to employ one on the water heater supply only. I had been looking at this with blinders on, because of the rule but now think I could possibly sell them on this as other owners are also having issues. I will do the calculations to figure out the grain size of the unit I will need and multiple it by the number of units to see what we'd be looking at and bounce it off the engineer who did the percolate testing for the septic system to see if it could handle the sodium volume from the discharge.
    WMno57 said:

    Robb,

    I think you are making this too complicated. If I were in your shoes (actually I am, I have rural hard water), I would get a cheap standalone water heater to heat your domestic hot water. When the cheap water heater dies an early death you replace it. Having the water heater separate from the boiler that heats your house is a good thing.

    I don't understand your aversion to water softeners. A new basic water softener uses minimal salt, and can be plumbed to soften hot water only. That isn't going to harm your septic system. Millions of rural homes are doing this. You alone, are not going to save the aquifer.

    "I think you are making this too complicated" you wouldn't be the first one to say this about me!!! LOL :# The system originally utilized two water heaters a 40 gallon for the in floor radiant and a 60 gallon for the hot water but they both came to the end of their life span shortly after I purchased and I wanted to try and go with a Combi system approach and free up some space and improve the efficiency, unfortunately I was too quick in my decision making and allowed a company to design the system based on their recommendations when I should have done more research which is how I arrived at my current situation. (but that's a whole different topic and I've gotten over it/them and just need to find the right balance for my current situation.)

    As far as the water softener??? I personally hate them and have had skin reactions in the past, but this again was before the advent of regen based systems so maybe I need to look at this again and utilizing one. However as mention above I will need to get the HOA to remove the ban of their use before I can install one.

    Thank you all for your valuable insights you've provided me. My path forward is to add the unions and Y screen for the check valve servicing and protection of scale build up and find and get approval for adding a water softener to the equation and run the Tagaki till it dies and employ a proper Combi/Mod boiler after that. At least I'm lucky in the fact I have a force air heating system as back up so no frozen pipes here.

    As always have a great day!
    Robb




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