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How hard? Draining hydronic heating system

zvalve
zvalve Member Posts: 83
in Gas Heating
How difficult is it to drain a hydronic heating system to replace a zone valve and then purge it. Should I use the valve on the bottom of the boiler to drain and purge or just drain?


Or use a valve higher up to purge?

Comments

  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Is the zone valve leaking?
    Need some pictures to provide better help.
    Need to see all the near boiler piping with its components

    There was an error rendering this rich post.

  • zvalve
    zvalve Member Posts: 83
    Zone valve not leaking but not closing
  • MikeL_2
    MikeL_2 Member Posts: 514
    edited April 2022
        As long as you're draining the system, I recommend changing the location of the auto fill valve; it's current connection point is less than ideal.
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,378
    edited April 2022
    I agree with @MikeL_2 regarding the location of the auto fill. Also @DanHolohan has a great explanation of why that is the wrong location, AND why if doesn't matter... until it does. I used to tell that to all my students when I taught Hydronics for the EHCC.org. It's a long explanation and if you don't have the problem, there is no need to digress

    Basically in your case @zvalve, it probably does not matter. I do see other issues.
    1. I don't see your zone valves. I do see an auto feed valve that has a small container below it. Is that what is leaking?
    2. The return pipe from the Tee fitting where two returns join to return back to the circulator might be too small.
    3. The aforementioned wrong location of the auto fill
    4. The leaking 3/4" copper x male adaptor at the circulator flange
    5. Improper air scoop installation. There is less than 18" of approach piping

    These items may make for poor design. But not necessarily. If your home requires less than 40,000 BTUh to reach the comfort level at design temperature, (the coldest day of the year), then the 3/4" pipe mentioned in #2 above is not a problem. If, however, you experience insufficient heat when it is very cold outside, then, a short piece of 1" copper may solve your problem.

    Another issue regarding noisy baseboard radiators (gurgling) can be solved by relocating the circulator and the auto feed valve at the same time you repair the leak. If you are not experiencing gurgling, then it ain't broke, so don't fix it.

    The original installer does not have great design skills when it comes to installing boilers, but that does not mean they did it wrong on purpose. I remember making those same mistakes when I was younger. After learning a lot from Dan H., I began to understand the how and why there is a better way to pipe boilers. Better design will make the system trouble free and last longer.

    If you have any questions about this post. feel free to ask me more specific questions. Also if you do have zone valves, they are not in the pictures you posted. Here is a clue about zone valves... you will have more than one thermostat

    Mr.Ed

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    MikeL_2MikeAmann
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,214
    Draining the system won't be a problem. Re-filling and purging without a proper purge assembly will be. Now's the time to install one.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    MikeAmann
  • zvalve
    zvalve Member Posts: 83
    Sorry that was an old picture and I had a leaky pressure reducing valve which has subsequently been corrected and it didn’t show zone valves
    Thanks Mr Ed. Good stuff I can contact you by PM?
     Thanks Alan,what is a proper purge assembly? Can you show a photo or diagram of one? How about the valve pointed at in the photo?
    Here are the zvalves

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,214
    Yes, the one you're pointing at looks good. When you're ready to purge, turn off the ball valve and open the hose bibb with a hose attached to a good drain location. Purge until all the air is removed.

    There is a second return in parallel right next to it without a purge assembly. Maybe it doesn't need one?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,378
    Here is a good video on how to purge the air from your baseboard loop. Just click on my name above then click on the video.

    Not my video, but just the best I've seen so far.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    zvalve
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    What's going on here?

    There was an error rendering this rich post.

  • zvalve
    zvalve Member Posts: 83
    Taco boiler feed valves https://www.supplyhouse.com/Taco-334-T3-Taco-Dual-Unit-Valve-Threaded-1995000-p?utm_source=google_ad&utm_medium=shopping_neutral&utm_campaign=Shopping_Neutral_MPLTV&gclid=CjwKCAjw9LSSBhBsEiwAKtf0nwGdcKtMmAmWZCPnsPD8e53tj9aLnMixQHWygW3edI6-oy7waHC5shoCl2YQAvD_BwE 
    STEVEusaPA
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,214
    I'm with Steve on this one. It looks like two feed valves. But thanks to @zvalve for clarification.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    STEVEusaPA
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Yeah I thought it was 2 feeds. Thanks for the clarification.

    There was an error rendering this rich post.

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