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Humming TriangleTube Modcon

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jad3675
jad3675 Member Posts: 127
I have a Triangle Tube Instinct 110 that feeds three radiant zones. The smallest zone is a bit small (I know, I know) and when the zone is the only one calling for heat the boiler will hit the setpoint. As the boiler modulates down to (eventually 0%) there will be a somewhat noticeable 'hum' (not foghorn or anything terribly loud) around 5%. I can't get the boiler to duplicate this sound if I manually bring the modulation down via the control panel with that zone open. It only happens when the boiler is making the adjustments.

I've checked the gas pressure and it is well within specs. Combustion was spot on in the middle, so I adjusted it a bit rich to see if that helps. No dice. There's zero CSST in the gas line. It's all black pipe.

I added a vertical 7 inches to the outside exhaust snorkel and that had the effect of pro-longing the noise from 5 or 10 seconds to around 30. I'm almost tempted to get rid of the PVC snorkel setup and go with a flat plate vent to see if that would ease the noise.

John

Comments

  • psb75
    psb75 Member Posts: 845
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    I had a noise problem with a new Lochinvar Noble 80. It was a very loud, resonant "fog-horning." I tried many of the fixes you mentioned. In the end: the dealer rep had to change something on a new motherboard (at the home office) and I swapped that in. Problem fixed. He told me that he "skipped over" the offending fan-speed that was causing the noise as the boiler was ramping up and back down. Boiler has worked fine since then. No charge for the motherboard...and all of my labor. :-(
  • hot_rod
    hot_rod Member Posts: 22,258
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    How long is the vent pipe? Really short runs can cause that noise, sometimes adding a 45 adds more restriction
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jad3675
    jad3675 Member Posts: 127
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    hot_rod said:

    How long is the vent pipe? Really short runs can cause that noise, sometimes adding a 45 adds more restriction

    It's 12ft, with 4 90s. The interior piping is Duravent, but it transitions to PVC outside. I could throw on a few 90s on the outside and see if that helps.
  • Derheatmeister
    Derheatmeister Member Posts: 1,549
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    Try Drilling a 1/2" hole in the intake pipe near the boiler ...Works sometimes at 10 000 feet.
  • jad3675
    jad3675 Member Posts: 127
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    Try Drilling a 1/2" hole in the intake pipe near the boiler ...Works sometimes at 10 000 feet.

    Hm. The boiler does have ports on the intake and exhaust, I may try removing the cap on the intake side and see if that helps.
    Thanks!
    John
  • Derheatmeister
    Derheatmeister Member Posts: 1,549
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    Not sure if leaving the cap of will do the job?
    When we drill the hole(Sometimes Multipal holes) we drill them out of sight on the back side of the pipe to avoid lengthy conversations with the customers. :D
  • PC7060
    PC7060 Member Posts: 1,175
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    My HTP UFT80 has a hum/resonant sound at low modulation rates. Nothing disruptive, just a slight resonance.   
  • jad3675
    jad3675 Member Posts: 127
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    Did some messing around with the vent this weekend - removed the two external 90s so that it essentially side-vented out of the house. No dice on that being the fix.
    Drilled a few 1/2 holes in the combustion intake side; nothing.

    I think I'll be giving TT support a call and see if they have any ideas.

    John
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,094
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    Have you considered putting the sheet music on the floor where the boiler can see it? I find that boilers and controls HUM when they forget the words.

    Edward Young Retired

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

    PC7060kcopp
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,622
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    Maybe add a buffer tank so it works better with the small zone. Probably modulating down too far.
  • Derheatmeister
    Derheatmeister Member Posts: 1,549
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    1. What are your O2,CO,Values at ?
    2. What is your elevation ?
    3. Propane or Natural gas.
    kcopp
  • jad3675
    jad3675 Member Posts: 127
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    1. What are your O2,CO,Values at ?
    2. What is your elevation ?
    3. Propane or Natural gas.


    1. O: 4%, CO2: 9.6% - This was as close as I could get them to the recommended target.
    2. 485 Feet
    3. NG
  • Derheatmeister
    Derheatmeister Member Posts: 1,549
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    Have you tried to run with the O2 at 4.8 % ?
  • jad3675
    jad3675 Member Posts: 127
    edited January 2023
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    Have you tried to run with the O2 at 4.8 % ?

    I adjusted it rich as a test...which I took to mean lower O2 (I went down to 2.5%). Did I do that backwards?
  • Derheatmeister
    Derheatmeister Member Posts: 1,549
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    Not sure...But i would try with a higher O2...
    We had humming/ harmonic or "whale in heat " type shounds which disappered when we adjusted our O2 to approx 4.8 ish % ..
    This was on some of the earlier Triangle tube PS series modcons..
    At 10.000 PLUS feet sometimes it is a hit or miss depending on the Manufacturer and the Combustion stategy..(Fan speeds,Orifices,shutters,Venturies)
    Some of the harmonic noises disappered when we adjust the O2 to about 4.8 %, sometimes it did nothing until we drilled a couple holes..
    On one TT which we did not install the noise never completely disapeared for the original installer or us. :(

    The other things to check CSST which you do not have and Viscocity of the system fluid..

  • GGross
    GGross Member Posts: 1,070
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    Just out of curiosity is the foam muffler that ships installed in the air intake installed correctly? I have seen some installers take it out even though there are big bold letters telling you not to. There is an additional insert for LP gas as well. This seems to be an instinct specific thing as I haven't seen it on the other boilers I deal with.

    If this is on LP gas I would make sure your model received the LP gas adjustment update. As far as I know they adjusted all of the ones that needed it in the field, this only applied to the first run of this model and never caused a harmonic issue for me, but would not let the boiler burn within combustion spec without very specific gas valve adjustments
  • jad3675
    jad3675 Member Posts: 127
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    Yeah, the muffler is installed.
    I'll try adjusting the O2 up to 4.8% before I give tech support a call.
    GGross
  • jad3675
    jad3675 Member Posts: 127
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    I adjusted O2 up to 4.8% and the humming didn't go away. The tone changed, I think?

    After I reset it back to the factory specs, I looked into adjusting the CH call blocking since it is short-cycling, but only when the basement zone calls for heat. From the factory, it was set to 2 minutes.

    I adjusted the CH Call Blocking to 20 minutes....and now it no longer hums when it goes down to 1%, and it was very obvious before the changes when it did that. It now fires for around 15 minutes, where before I changed the blocking, it was running for 5 minutes before ramping down. Yeah, bad on me for not checking and adjusting that earlier - I didn't realize how much it was short cycling when it was the only zone.

    Thanks everyone for the help and ideas. I appreciate it.

    John