3 phase compressor

[stegmo2]

i have a rooftop 10 ton 3 phase unit (2- 5 ton hermetic compressors) and had one of the compressors go bad. I replaced the compressor with a one i took out of a unit earlier this year that i replaced. My question: Does it matter if it runs a different direction that it was in the other one?

Thanks

[The MG Pony]

if it runs in the wrong direction chances are you hooked the phases up wrong

[Blueheeler]

If it is a scroll it matters. Hook your guages up and observe. Usually the sound will tell you if you hooked it up wrong.

[stegmo2]

it is a recip. I have high head low suction and was wondering if it mattered which way it runs. like i said earlier i took it out of a unit i replaced. it ran who knows what direction in the old one. i am going to replace the unit soon so i was just trying to buy time with using this other compressor.

[fridge doctor]

It doesn't matter for a recip, hermetic or semi-hermetic. Any way is OK. Regards

[bobkellyb]

Sounds like the customer should bite the bullet and
replace the Air Conditioner!

[kipetkov]

the best way for you is if you have a phase rotation meter to check on the old unit.

[Eeram]

Like fridge doctor said, if it is a piston job, it does not matter in what direction it runs. However, if it is a semi hermetic compressor with a positive displacement oil pump, it is a different scenario.

If a semi hermetic compressor with an oil pump has worked for a amount of time in a certain direction, and you reverse the rotation, you can find that the nett oil pressure of the oil pump is lower than the previous installation or run, because!

The oil pump tends to wear in one direction, with good oil pumping. When you change the direction, the pump must try to match surfaces in the opposite direction which could lead to insufficient oil pressure, or even sometimes (which is very rare) oil pump failure.

When you changed the compressor, did you vacuum the whole plant or just the compressor? Why did the previous compressor go bad?

[Brian_UK]

How do you know which way the compressor is running?

[chillin out]

How do you know which way the compressor is running?

LOL... thats what I was wondering.

Did you strip the end plate off and then switch it on?

Chillin

[Brian_UK]

Or if a hermetic maybe he fitted a sight glass in the shell

[stegmo2]

Thanks fridgedoc and eeram! Im glad we have people with real answers instead of moderators trying to be comedians. The old one was 25 years old and had an open winding. I cleaned it all and installed the used compressor it seems to be working now. I had worked on the 06L carriers and as you said it matters with a positve displacement oil pump. I didn't know about the others. Hopefully won't have to rig anymore.
thanks again

[chillin out]

Just trying to lighten the place up a little...lol

hermetic compressors

Now you say its a recip?

A little more info on the 1st post would have helped.

If the direction worries you just swap any two phase connections round and it will spin the other way.

Chillin

[penair]

you guys really go off the channel sometimes, (end plate?). stegmo said the compressor is hermetic..... if he is getting low pressure suction and high pressure discharge on the gauges then all is well.....

[chillin out]

you guys really go off the channel sometimes, (end plate?). stegmo said the compressor is hermetic..... if he is getting low pressure suction and high pressure discharge on the gauges then all is well.....

Please re-read the thread properly.

He started off saying it was a hermetic then changed it.

Chillin

[BigJon3475]

http://www.tpub.com/doeelecscience/e...cience2184.htm

[AzRob]

When a compressor starts up wont its movement from the torque of starting indicate the direction its turning? Never thought of "compressor direction" until I read this post, ya learn something new all the time!