bubbles in a proper charge

[claude11]

I seen bubbles in the sight glass the other day and assumed the system was low on HP 80 . I add some but then it was over charged ( bubbles were gone but the head pressure was very high) . I reclamed some of the over charge , which brought down the head pressure and the system works OK but the bubbles are back . Any Ideas??

[Toosh]

Hi #1 is the unit condensing properly is the superheat correct are you at altitude ie the rockies i worked in alberta for years and saw a few things in my time.

regards Toosh

[Andy W]

TEV incorrectly sized?

[LRAC]

I seen bubbles in the sight glass the other day and assumed the system was low on HP 80 . I add some but then it was over charged ( bubbles were gone but the head pressure was very high) . I reclamed some of the over charge , which brought down the head pressure and the system works OK but the bubbles are back . Any Ideas??

Just because bubbles are present in a liquid line has no bearing on the equipment status or operational condition.

You only need liquid at the TXV not all the way back to the condensing unit. Check other items first, superheat and subcooling if all seems ok leave it alone.

Regards
Lrac

[mecassa]

Bubbles in the sight glass, erk, sounds as though there are non-condensables in the system.

[Peter_1]

1. Partially blocked filter?
2. What's your SC?
2 important items to check first

[lana]

Hi there,

If your filter is installed before the sight glass then bubbles could be from blocked filter, as Peter mentioned. Any blockage before the sight glass could cause bubbles.
On the other hand, when TEV opens and closes you will see bubbles which come and go and this is normal.
Again as Peter mentioned, measure the sub cooling.
Hi discharge pressure with high sub cooling means overcharged. Low suction pressure and low sub cooling means under charged.

Cheers

[taz24]

I seen bubbles in the sight glass the other day and assumed the system was low on HP 80 . I add some but then it was over charged ( bubbles were gone but the head pressure was very high) . I reclamed some of the over charge , which brought down the head pressure and the system works OK but the bubbles are back . Any Ideas??

Sight glasses will bubble at times and it does not always mean short of gas.

Start with the basics.
Was it working?
How long has it been working?
What has changed now for it not to work?

HP80 is it a zeotropic?
If refrigerant has been added in the past to top up the system could you have an imbalence in the make up of the refrigerant due to temp glide.

taz.

[claude11]

Thanks guys
I'll try changing the filter .The system is working fine . I just thought it may have been a little low

[LRAC]

Thanks guys
I'll try changing the filter .The system is working fine . I just thought it may have been a little low

Don't touch it leave well alone if its working, you'll open up a can of whoop ass.

My old boss said no point fixing it if it ain't broke.

[Peter_1]

Agree, don't changet he filter if that isn't the real cause.
First measuringn then determining what the fault is and then finally change the erratic piece.

[chillyblue]

Hi

I had one the same yesterday, refrigerant R409A, suction pressure 1psi, discharge 160psi, superheat high, subcooling, very high (bottom of the condenser was stone cold, top of condenser red hot) liquid line sight glass nearly empty, liquid line length only about half a meter. i had to heat up the TEV to get it to open, the suction pressure about 6psi subcooling good, no change on the discharge pressure or the amount of subcooling, but the liquid line sight glass is still showing nearly empty. i have felt the liquid line between the drier and solenoid valve and the TEV there is no temperature change indicating no blockages!! finally the cabinet temperatures it is operating seem to all be fine.

What do you all think??

CB

[lana]

If you have sub cooling then for certain amount of blockage (pressure drop) in the liquid line would not show any temperature drop. This is a very common misunderstanding.
Draw a p-h diagram which shown sub cooling. Then you will see this. In the sub cooling area the constant temperature line is nearly vertical, this means if pressure drop occurs (blockage) then for a certain amount of pressure drop there will be no temperature drop until you get to the two phase area.

Hope this is clear.
Cheers

[The MG Pony]

Most my systems the sight glass is half empty during pull down, once system is to design it is full and system opperates wonderfully. Just use the sight glass to tell you if moisture is pressent and refrigerant is moving, nothing more!

[Dr._Fleck]

If there are tiny bubbles in the sight glass my old boss used to say it's just the TEV opening and closing.
I've seen it many times since and don't worry about it.