They ran it backwards

[Arkma]

I have a customer that ran their 3 ton Copeland scroll compressor backwards for the weekend. How can we verify the compressor is shot. R-22 system high side 140, low side 135. that about sums it up dosen't it?

[chemi-cool]

They can't run back wards!!

There is a kind of clutch to prevent it.

But they sure can burn back wards.

Verify that compressor is shot?

Install a green led marked RUN parallel to the contactor coil. When its off, compressor is shot.


Chemi

[Arkma]

Thanks Chemi, We have a run light installed on the system, which is "on" by the way. The compressor is running, but it is not generating any pressure. I'm fairly confident that this compressor is shot...

[chemi-cool]

Stop it before it burns and change direction of rotation.

I belive its a three phase compressor cause if its not then the shaft inside might be broken.

Chemi

[Peter_1]

They can run backwards.
First thing you need to do when starting up a scroll is measuring pressures HP and LP. When they 're not in the expected range, reverse phases and check again.

After some time, you will hear if he's pumping correct (and feel it on the discharge and suction lines on the compressor)
You also can install a reverse phase protector (like Daikin do in his AC's)

I suppose you changed phases and problem remained the same?
If so, my advise: replace compressor, suction filter.
Normally they can run a long time backwards but the main thing which is happening in the first running hours is a very fine grinding, iron of upper scroll againts iron of lower scroll with some oil between i tso that they fit exactly together.
A scrolls pumping capacity increases after some running hours due to this grinding.

Good lesson afterwards, open up the compressor and look what happened.
Share it with us.
My gues: scrolls completely worn/grinded out the wrong way.
Or the internal safety check valve has opened and stays open.

[frank]

I had this a while ago and it was covered in an old thread http://www.refrigeration-engineer.co...96&postcount=1. Hope the link works as it's the first time I've tried to paste a link!

Ooops - try this one http://www.refrigeration-engineer.co...02&postcount=4

How do we do it properly Dez?

[Arkma]

Yes, phase is three phase. customer reversed phase and problem still exists. No cooling and the pressures are equal.

[chemi-cool]

Hi Peter,

The last scroll I've replaced was turning backwards and made a bad noise, changed direction and it was fine.

The Copeland people here told me to check direction but if you say it can run backwards I'll have to open one and see how it works on the inside.

chem

[Coolie]

Hi Peter,

I'll have to open one and see how it works on the inside.

chem

Check http://www.copeland-corp.com/cp_rf/p...cts_scroll.htm out.

It explains and shows how a scroll works

[Peter_1]

when you get a compressor than runs a high suctions side and a low highside, its called an " inefficent compressor " ,.....Heres what you will see in an Inefficient Compressor: discharge pressure low, suction pressure high, superheat high, subcooling high and amps low

I disagree with this statement almost for 100%: high suction and a low high side is a super efficient compressor.
Explain us why you see it otherwise but you're completely wrong.

[shogun7]

I have a customer that ran their 3 ton Copeland scroll compressor backwards for the weekend. How can we verify the compressor is shot. R-22 system high side 140, low side 135. that about sums it up dosen't it?

Most scroll designs have a groove machined into the scroll "tips" where a "tip seal" is inserted. The tip seal's sole purpose is to prevent leaks when the fixed and orbiting scrolls are mated together and running.
Copeland's scroll elements are precision machined to microns of an inch in length, providing a metal-to-metal sealing surface that polishes itself in over time. It actually improves the surface microfinish as it runs but if it runs backwards any length of time the sealing surface is destroyed and the compressor is for all practical purposes useless

[Gary]

when you get a compressor than runs a high suctions side and a low highside, its called an " inefficent compressor " , I changed this scroll compressor out-404-a for some gelato cases. same thing some smart-asses, wired it backwards, after it used to run good, and then, i had to change it out, if it doesnt get the right pressures after swapping the phase correctly then there you have it!, Heres what you will see in an Inefficient Compressor: discharge pressure low, suction pressure high, superheat high, subcooling high and amps low

Since the saturated condensing temp (SCT) is only slightly above ambient, and the liquid line cannot drop below ambient, the subcooling will be low, not high.

Likewise the saturated suction temp (SST) will be near ambient temp, and the suction line cannot be above ambient, so the superheat will be low, not high.

Low SCT and high SST is common to both inefficient compressors (abnormal) and high efficiency systems (normal). It is not quite as simple as you think. In this particular case, it is extreme enough to be obvious, but in a borderline case, the symptoms you describe are not going to tell you what you need to know.

[Peter_1]

okay, think about it!?! .....the discharge air side of the coil, thats the 15 degree design with an r-22 high temp ...!

So, I thought about it and my conclusion remains the same: wrong.

Sorry, but English is not my mother language so your explanation was almost not understandable for me.
It's no critic on you personally but you must use shorter sentences, comma's, more points and start new sentences with a capital.
Your statement were 2 sentences.

Although, I tried to read what you said and tried to understand what you said but you re-invented the hot water and turned centuries old thermodynamics laws upside down.

I see now when reading next posts to yours that also Gary disagrees with you.

Something else... when I was at Copeland Welkenraedt (here in Belgium) where they make the scroll compressors, I asked there if a compressor can break mechanically if it runs a longer time backward.
They said it will not break but the motor will be cooled not enough and it will trip on thermal safety. But it will not break the scroll itself.

[wesmax]

I have a customer that ran their 3 ton Copeland scroll compressor backwards for the weekend. How can we verify the compressor is shot. R-22 system high side 140, low side 135. that about sums it up dosen't it?

you are rite you cannot run a scroll backwards unless you want to replace it
wesmax