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Posted by bus_driver (My Page) on
Tue, Nov 1, 11 at 8:25

Need comments from the pros. My upper level heat pump air handler and coil are in the attic. It has a TXV added by the installer to boost the SEER to 12. This system is now over 6 years old. The installer installed an 11 SEER coil (among his several goofs) and the Trane rep instructed him to add the TXV. It has worked without technical problems. But do TXVs sometimes make noise? The noise varies, sometimes faint buzzing of changing frequency and other sounds. The noise of the blower is consistent and I do not think it is the blower.

Follow-Up Postings:

RE: txv

sounds like its under charged. Yes txv can make noise.

RE: txv

that is a good question. Maybe some techies can shed some light.
My heat pump system has made a slight buzz type of noise from day 1 when it is in heatpump mode. I would almost say its like a hum. It doesn't make this noise when cooling in A/C mode or gas furnace mode (I have a dual fuel system).

I have listened carefully and it is coming from the coil. I'm wondering is it because of the way the txv was installed? My txv was installed in the field and wasn't installed on the new coil from the factory?

Or could it be because slightly under charged? Length of lineset from outdoor unit to coil is about 33 feet. We added almost an extra 1 pound of R-410 I think when it was installed since the line-set was pre-charged for 15-20 feet I think.

No problems whith performace. I've tested the heat rise coming from the vents compared indoor temperature. It works good.

The humm is much more noticeable when coming out of defrost mode and the hot heat from the gas furnace is blowing over the coil just as it renenters heatpump mode. The louder humm goes away as the 'hot' heat from the furnace is blown out thru the vents and only the heatpump heat is blowing.

RE: txv

bus_driver...the sounds you hear could very well be coming from the txv, a faint buzz, a hiss, whoosh etc. depending how much refrigerant is being introduced into the evap. coil. It will vary as the temp of the evap. coil varies.

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