Flushing large hydronic system - help needed

Discussion in 'HVAC Heating & Cooling' started by alternety, Sep 22, 2020.

  1. alternety

    alternety Like an engineer

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    Washington
    The house is large. Two floors and 3 outside areas. Boiler is a WM series 2 110 boiler. I have a large number of individually controlled loops. External links also need a good flushing.

    What I need to know is the best approach to drain and clean the system; then put in water and protective chemicals. There is a lot of segments and controls. I have participated in flushing the system before and as I recollect we essentially allowed water in the lowest area to be forced up to the system. Then opening valves on each loop one at a time with a hose out the window from the manifolds.

    I can try to flush isolated pieces. Water heater tank, buffer tank, boiler and then isolate the remaining equipment.

    I would think I would have more of a problem with captured air and a hose out the upstairs window. The alternative is drain everything (with air) and start from scratch. Adding treatment chemicals when the system is refilled.

    I could really use some ideas on how to continue.
     
  2. fitter30

    fitter30 Active Member

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    Peace valley missouri
    Why do you think the system needs flushing? Radiators, fin tube and or fan coils ?
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Each time you flush a hydronic system, you'll be adding gasses that are dissolved in the water you add. Some of those things will include oxygen, which will exist until it rusts whatever can be rusted. Nitrogen and CO2 that could also be in the water can become acids which is where the chemicals can help buffer the solution. After all of the introduced gasses react with your system's internals, the water becomes fairly inert, and shouldn't need to be replaced or flushed. So, flushing on a regular basis probably isn't a great idea...

    To accomplish it, though, you'd need to manually open each zone individually and open the refill valve to push the water out. Depending on where you can open it up will depend on how easy it will be to prevent air pockets or to purge them. You will need a working air extraction device in your system, as the system goes through heating cycles, some of the entrained gasses in the refill water will then be able to be extracted.
     
  5. alternety

    alternety Like an engineer

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    Hi, LastPass had a hernia and I have not been able to post.

    The boiler manufacturer requires a flushing with a specified chemical, followed by another chemical for long term use and Ph tracking. I do not want to argue about this requirement. I am trying to decide on the best overall solution for cleaning. I have both chemicals on hand.

    I have the choice of:

    - draining all the system components from the top of the system and then flushing with fresh water. This will be followed by an additional water fill and then adding the protective additive. I have built a little injector system using a pressure sprayer and some parts. This works fine.

    - forcing water from the basement to the highest available piping connection. Same general approach. But a different configuration.

    My thought here is should I start from the basement or the top floor. I would like to have an idea of the easiest flush direction to minimize air being trapped. Use low pressure air to clean the pipes to the lowest point, or push the water up with fresh water and remove old water and minimize air in the system.

    It is a moderately complicated configuration and I am alone. I have access to all the good parts.

    Any additional approaches will be gratefully considered. I just want to make it as easy as possible for me. This is my fourth boiler and fourth well pump. I have had some experience.
     
  6. fitter30

    fitter30 Active Member

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    Is this your boiler? photostudio_1601239011612.png
     
  7. alternety

    alternety Like an engineer

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    No. It is a WM EVO.
     
  8. fitter30

    fitter30 Active Member

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    If your boiler water isn't black i wouldn't flush it just put in the inhibitor. Going to flush the system you need to put in the cleaner and circulate it for at least few hours or longer to give it time to work, drain fill circulate drain again do that three or four times then fill with your inhibitor.
     
  9. alternety

    alternety Like an engineer

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    Please, stick to the question.

    I need to know how best to drain the existing fluid (with current old adative currently installed), flush with fresh water, and reinstall fluid with manufacturer required chemical. I am not searching for any alternative for any other purpose than noted above.

    I just really want to know one single thing; Drain from top to bottom or pressurize to emit old fluid out the top of the system. Then I will drain and clean the system. I actually understand the process and materials.

    Can someone please offer a perspective on this function only? I need to get this done.
     
  10. alternety

    alternety Like an engineer

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  11. alternety

    alternety Like an engineer

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    Hi, I brought this post down to continue the details. Nice information.

    This system has had a long and terrible history. There are fluids in the system that need to be cleaned out. There are some unused circuits that are filled with an older material which needs to be removed. All other piping has a cleaner in that has been in longer than it should be. I have all the chemicals (per WM).

    I want the system cleaned. The only question I have - How best to replace the existing water.

    From what I have seen (I spent some time on the fluids earlier). I had a second person to help. In that exercise, I ran the individual valves, sending the water outside, and running each valve until water flow is steady and air is purged. The helper control water flow. This worked OK. I have more valves and segments to do a complete flush. These are difficult to reach and control.

    An alternative is to work with one person (e.g., me) and drain the existing fluids from the system from top down. I am very reluctant to have someone in the house. Think COVID.

    The system is complicated and a lot of difficult piping (tanks) needs to work the items as the system is purged/replaced. I think I could do it purging most of the tanks and then filling from the lowest point.
     
  12. fitter30

    fitter30 Active Member

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    Retired service tech
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    What valves do u have for flushing? Are they drain valves or air bleeds? If the system is that dirty cleaner and a bag style water filter that can be cleaned can be piped in and pump can run till filter doesn't stop up.
     
  13. alternety

    alternety Like an engineer

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    Location:
    Washington
    I have faucets on the piping pretty much over all of the piping. All of the manifolds have a hose fixture for draining. I tend to over design.

    The manifolds have individual valves which can be operated manually to flush one loop at a time.

    House (well) water can feed from the basement and upstairs a hose can be run outside from the manifolds. Or the other way around. I can start at the top or the bottom.

    The fluid in the system now is a cleaner that has been in there for a rather longtime. I will flush this, fill with clean water, and insert the required treatment chemicals. As required by the manufacturer of the boiler. I have all the specified materials.

    That is all I am trying to get advice for. Will it be easier/better to flush top down or flush up. I can access and control everything. I do not have anyone available to help me. So the approach selection must be for a single worker.

    I also discovered today that there is a rather large ant colony that has has decided to build inside my water storage tank. This will not be fun, and I will waste a bunch of scarce water. The fun never ends.
     
    Last edited: Sep 30, 2020
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