Sanyo VRF & SVK boxes

[toolong]

Hi guys (and girls!),
I have a problem on one of our projects with a number of Sanyo svk boxes which are emitting a vibrating noise, similar to a small hammer drill, for around 2 - 15 seconds, although infrequently. It's a very quiet office so is very noticeable. We've put lots of these systems in and never had this problem before. I know svk boxes click when the solenoids change over but not this sustained vibration.

We've had Sanyo technical bods in and, as a result, the svk boxes have been changed for ones with rubber seated valves. However we still have a problem, although it's a little better than it used to be.

All I want to know is - has anyone else experienced this problem with Sanyo svk boxes and, if so what was the outcome?

Regards to all

Reg

[JoeAT50A]

SVK used to have for locations where low refrigerant noise is required. This is SANYO claim and other makers also have some sort of similar to eliminate the hissing noise. However SVK itself is noisy, wrap it around the Solenoid valve with some think sticky insulations.
Some time locations installations, orientation of refnet joints are headache, pay attention to all these. We normally place svk somewhere away from the rooms for example corridors or pentry room.
There are many sounds, hammering sounds, vibrations sound, hissing sound and so on.
Refrigerant amount must be adequate enough, SOG or long piping or wrong pipe size will create more noise.
Normally heating units (gas) are more louder than cooling (liquid).