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Mini-Therm II JVT100Ndi Banging/pressure issues

ten10ten
ten10ten Member Posts: 5
in THE MAIN WALL
I have a Mini-therm II JVT100Ndi boiler/water heater combo. I believe it was likely installed in the mid 90s. I've lived in the house for 11 years with no issues. Recently my pressure valve was replaced after it began spewing water. After assessing the issue, the HVAC company came back 2 days later to replace the valve. He noted that he didn't anticipate something (I didn't catch what) to be empty of water, so the half hour he anticipated to change the pieces turned into ~3 hours where he had to, I believe, bleed the system of air. After the change, we started hearing banging in the walls (seemed to be coming from the pipes).

This banging didn't occur when the heat was on and in tracking it for 1.5 weeks, it is not related to the heat coming up or off. It's not related to the water being turned on or off. The banging started slowly with me hearing it a couple times a day (like someone was inside the pipe hitting it with a hammer) for about 10 secs. It increased until it was happening almost hourly. There was a day where I used the heat again and after that the sound changed slightly, sounding like shoes in a dryer. It would last about 20 seconds each time and again, came almost hourly in the evening (my son would report hearing it 1x or 2x when home during the day).

The HVAC company returned and hoped to hear the sound, but didn't. I played recordings for him and he said it sounded like air in the system. He didn't want to do anything but bled it again, noting some air came back. He left at 3 and it started again happening at 329pm, 425pm, 535pm, 645pm, 754pm, 903pm, 1010pm (I actually went to bed at 845 and was woken up multiple times by the sound). The sound was definitely quieter and lasting about 15 seconds.

Of note, after reading my manual today, my system says pressure release at 30psi and that it should be set to 12psi. He told me he set it at 15psi. He also said I had too many air release (I wasn't fully following this) handles and he turned all off but 1.

Any thoughts on this? I imagine air got into the system when the valve was changed, but unsure why having it bled 2x is still leading to issues. I'm also very curious about why it seems to be happening on a schedule. I'm hoping for some input before I call them back again. I do plan on an estimate for a new boiler, as mine is quite old, but frustrated that this seems to be a result of the fix, and now I'm $600 into it. Thank you!

Comments

  • Zman
    Zman Member Posts: 7,569
    Maybe post a few pictures of the boiler from a distance and a video of the sound?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ten10ten
    ten10ten Member Posts: 5
    edited March 2021
    Sure.  I isolated the sound to inside the boiler last night and was able to recreate the sound by turning the heat on and off (this hadn't worked previously).

    I included pic of boiler (very tiny basement so hard to get a full pic) and replaced part.

    Video of sound by furnace after heat shut off: https://youtube.com/shorts/-BhiKq9tysg

    Video of sound that I was hearing hourly in bedroom (3rd floor, boiler in 1st floor) - in person it's way louder than the video indicates:  https://youtube.com/shorts/l5kZhz0Dahk



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