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  1. #1
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    Question about gas regulator placement on KN-16 boiler

    Hopefully someone can help me understand this one. I've read in manuals before for other boilers that they wanted the gas pressure regulator the equivalent pipe length of 10 feet from the inlet of the gas valve, with 90s and 45s counted. This KN-16 I worked on was having some issues with inconsistent gas pressure, and the manufacture's tech support told me the regulator was mounted too close to the gas valve. I looked in the manual and this manual for the KN-16 states the regulator needs to be 10 pipe diameters (instead of feet) from the gas valve. My question is, does "pipe diameters" mean the same thing as "equivalent pipe length?" In this same KN-16 manual, it has a table for "equivalent pipe length" for fittings.

    Here's is a link to the manual: PAGE 20

  2. #2
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    Equivalent pipe feet refers to the pressure drop for a given diameter and shape.

    The reference to pipe diameters is a simple formula to move the regulator further from the valve as pipe diameter increases so the gas flow has a chance to stabilize coming out of the regulator and create a buffer so the regulator doesn't chatter when the valve suddenly closes.

  3. #3
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    How far away is the regulator? If you are using 1 1/2" that is only 15" away
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  4. #4
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    Quote Originally Posted by hearthman View Post
    Equivalent pipe feet refers to the pressure drop for a given diameter and shape.

    The reference to pipe diameters is a simple formula to move the regulator further from the valve as pipe diameter increases so the gas flow has a chance to stabilize coming out of the regulator and create a buffer so the regulator doesn't chatter when the valve suddenly closes.
    So if I have a 2 inch gas line, what would 10 pipe diameters be?

  5. #5
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    Quote Originally Posted by buttwheat View Post
    How far away is the regulator? If you are using 1 1/2" that is only 15" away
    It's 2 inch pipe. So if it truly means 10 actual pipe diameters, that's 20 inches. That can't be right. It has to mean something other than actual pipe diameters.

    The regulator is about 2 feet of straight pipe, and one 90 away from the gas valve.

  6. #6
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    Well it would mean in your case a minimum of 20 inches of straight pipe. What is it currently?

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  7. #7
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    Quote Originally Posted by Boiler Guy View Post
    It's 2 inch pipe. So if it truly means 10 actual pipe diameters, that's 20 inches. That can't be right. It has to mean something other than actual pipe diameters.

    The regulator is about 2 feet of straight pipe, and one 90 away from the gas valve.
    No it is really as simple as that
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  8. #8
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    Quote Originally Posted by buttwheat View Post
    No it is really as simple as that
    Welp there we go then. That's what it sounds like but the factory rep said it was wrong. It was definitely more than 20 inches away from the gas valve.

  9. #9
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    Just replace the regulator then go from there
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  10. #10
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    What make/model regulator are you using?
    There is not better place for the working men than the union! 100% UA the only HVAC union!

  11. #11
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    Is the pipe size correctly to move the cfh the boiler requires?
    "If history repeats itself I am so getting a dinosaur"

  12. #12
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    Quote Originally Posted by valdelocc View Post
    What make/model regulator are you using?
    That info I need to go get. I was going to call the manufacturer and see what they recommend.

    Quote Originally Posted by Hrdworkingacguy View Post
    Is the pipe size correctly to move the cfh the boiler requires?
    Pipe is sized correctly. I confirmed that with the factory rep.

  13. #13
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    Sometime the factory would recommend the bare minimum like run of the mill cheapo Maxitrol, can always go higher in performance and quality with a piloted Fisher or Sensus.
    There is not better place for the working men than the union! 100% UA the only HVAC union!

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