Pennsylvania ClimateMaster GEO unit sings a tune, with harmonic stepping

Hello,

I have a pretty big geothermal setup (10 tonnes of capacity across 5 geo units and a single closed loops system composed of 7 deep, vertical wells). It works as advertised, for the most part (credit to a quality install), but one of the 5 units emits a loud, and very difficult-to-ignore series of stepping harmonic sounds that seem like they'd be caused by a variable speed pump, or compressor, or something like that. It sounds almost like it's coming from the refrigerant lines or in-line filter, or being transmitted through them. The sound is very much localized to the Geothermal heat exchanger and not the air handler, which is in a different area of the house.

The Geo unit is a ClimateMaster TES026BGD02ANNS.

I recorded the following video, which is representative of what it sounds like:

https://share.icloud.com/photos/0uH0K7iJtghbZwL5E8ir_Z_6A

As far as I can tell, the noise is only heard when we're set to heat and the weather is mild, causing the unit to be cycling on and off, in and out of stage 2 etc. It is not heard during cooling season, nor is it heard in very cold weather when the unit is heating constantly and working hard. We're able to monitor the system using our ecobee online portal and I think the timing matches when the unit turns off completely, but I can't be certain.

Our installer is stumped. Likewise the distributor they use. Perhaps someone here will recognize this or be able to offer hints on things I can try to attempt to track down the cause? I used the quiet operation of geothermal energy in my pitch to the wife and she looks at me with 'that look' every time it sings, which it'll do 20 or 30 times when it's mild outside.

Thanks for any ideas, we've grasping at straws here.

-Darren

 

something is vibrating in resonance at that compressor speed (this is a split system correct and the fan part is remote to this?). may not even be the unit and could be something near the unit that vibrated due to contact. I would clear anything stored near it away, take the covers off the unit and be prepared to sit there and try to find the source. For vibration stuff, I tend to like to grasp things with my hands so they can't vibrate the same way to eliminate possibilities. consider any piping coming off of the unit as a potential source too and hold on to them as well. this can be an incredibly slow process but you will eventually find it. This isn't so much a geothermal problem as a general moving/rotating stuff causing vibration issue.

 

Hello,

Just refreshing that link here because the one above expired:

https://share.icloud.com/photos/0MZ4ABnSf5zC55ReBCFBpqb0A

This is a split system, that's right. The air handler is not close to the geo unit. The noise is localized to the geo unit.

After more study, the noise sounds like it's coming from the refrigerant line, ... it's especially loud near a SANHUA liquid line filter drier on one of the refrigerant lines just after they come out of the Geo unit. It's been hard to get my installer to take this seriously because I cannot cause it to happen on demand, you just have to sit down there in the basement on a mild day and two of the 5 units we have will whistle/sign these tunes. Their current working theory is that is has something to do with the geometry of the lines and a bend that is perhaps too sharp. Prior to that some sort of a weight was installed in the geo unit, but that had no effect at all. They half-heartedly changed the geometry of at least one part of the line (I was not present) and left, and as far as I can tell the change had no effect.

It seems like it's on me to somehow narrow down where this is coming from. If anyone can offer any hints/suggestion or things to try, I'm all ears!

-Darren