Evaporator Sound unusual

[swimmer32]

Just wondering if I can hear peoples opinion on this.

I had a 7kw Panasonic split installed over a run of 11 or 12 metres.

After the install, the tech came back to add extra refrigerant due to the run being over 10 mtrs.

It was fine before, although with a slight hissing sound (which is why the tech thought the refrigerant may have been a little low).

Now (with the extra gas) I find that the indoor evaporator unit makes this constant noise, and it's quite noticeable.

Particularly when the compressor ramps down and just idles low.

It used to only do this on start up for a very short while, but now, it just does it constantly.

The closest thing I can tell you it sounds like is when a steam iron releases steam.

I made a basic recording to help identify the sound right next to the evaporator.

I can also hear it in the pipes just outside the unit, and it's ever so quiet (but more of a hissing sound) near the condenser outside.

I'm wondering if it could be possibly overcharged or something, as this is not a normal operating noise.

Would appreciate any help or feedback/advice.

https://docs.google.com/file/d/0By_0...p=docslist_apihttps://docs.google.com/file/d/0By_0...p=docslist_api

[chilliwilly]

What size lineset did you use and did you calculate pipe work volume before adding the extra charge, or did you just keep adding until the sight glass at the CU was clear?

This may just be sufficient to clear the sight glass but the reserve liquid in the receiver may eventually be too low when the xv demands more liquid and cause further bubbling and a shortage of gas, hence the hissing noise at the xv. Sometimes its wise to install an extra sight glass adjacent to the evaporator to give a more accurate indication of the prescence of liquid.

Is the orientation of the liquid line dryer correct, if its on a verticle climb with liquid flowing upwards into it after a horizontal run then there is a chance that the liquid could expand and cause bubbling in the liquid line for a longer period than if liquid was downward flowing into it.

Is the xv phial securely clamped and superheat setting correct, is there excessive condensation on suction line or icing near compressor, was the unit precharged with refrigerant or OFN, was the tightness test successful, is there a leak on the system?

[lana]

Hi there,

Is there any vertical pipe on suction line? If so, is there oil trap installed at the bottom of vertical line?

This sounds like oil coming down on vertical pipe when compressor stops or capacity reduced.

There are two important things to consider in pipe sizing and layout. One is the diameter and the other is oil return in vertical lines. If the diameter of pipe in vertical line is not correct then oil will drain downwards hence the noise. If diameter is correct for max capacity, but the layout is not correct (maybe double riser is required) then when compressor capacity is reduced , again oil drains down.

Cheers

[swimmer32]

Thanks for the replies guys, but that stuff is all way over my head unfortunately.

I just don't know why it didn't do it before, _until_ he put the extra refrigerant in - so assumed it must be related to that.

It's pretty bothersome, and am worried that it's doing some sort of harm or damage somewhere.

[RANGER1]

Thanks for the replies guys, but that stuff is all way over my head unfortunately.

I just don't know why it didn't do it before, _until_ he put the extra refrigerant in - so assumed it must be related to that.

It's pretty bothersome, and am worried that it's doing some sort of harm or damage somewhere.

Call them back, as it does not sound normal.
Is it cooling OK?

[swimmer32]

Yeah, I'll have to call them, or someone, to have a look at it.

It just can't be right.

It seems to cool quite well, but I haven't been using it much due to the fact that running it irritates me, and I'm concerned if it may be doing some harm.

[swimmer32]

In addition to all of this, I took the cover off the outside wall where the pipes exit before going into the roof space.

What I can tell you is that it is definitely on the smaller diameter line going into the indoor unit.
You can touch the pipe, and can actually feel the noise as well as hear it, so whatever the problem is, it's before it gets to the indoor unit.

The indoor unit just amplifies the sound through it's coils.
There is section where a slightly bigger diameter pipe is brazed on the smaller diameter pipe – joining the two. So small pipe, bigger pipe, small pipe again.
Also, it only makes this noise in cooling mode. It's dead quiet in heating.
This help anyone?

[swimmer32]

I don't mean to go on about this, but I'd really like to hear from you guys.

Taking the above into account, could this join in the thinner liquid line cause the problem I'm describing?

https://www.dropbox.com/sc/tt08t7vdk...Ogf2e4kcuOLHDa