Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Lennox GWM, Dunkirk VLT

Youngplg Member Posts: 1
We have an install that was installed in 2016 and we have a reoccurring harmonic noise in the heat exchanger. These boilers come with a internal primary loop so flow through the heat exchanger should not be an issue. We have this boiler set to factory specs for CO2 which is what they want us to set it with. We have even tried different analyzers to set it up. They have had us replace the gas valve and no change. It does not make the sound all the time. In fact many times we are there we hear nothing. We have installed several of these boilers and the first dozen were no problems at all. Now we seem to be getting this noise in a lot of the boilers. It is usually around 60-70% where this noise is most noticeable. This unit is on natural gas but units on LP make the noise as well. Looking for any thoughts or suggestions on what could be going on. Thank you


  • DZoro
    DZoro Member Posts: 1,048
    Does it ever fog horn when the cover is off?
    How do you have it vented?
    How is the gas set up?
    If your there when it fog horns cup your hand toward the intake and see if it stops fog horning.
  • Ironman
    Ironman Member Posts: 7,379
    Two things: set the co2 to the highest level the manual allows. If that doesn't correct it, remove any CSST that's within 10 feet of the boiler and replace it with a larger size or black iron. The CSST is the cause of harmonic noise.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.