3 phase condenser

[ProgressiveAir]

Could anything be done to change out an existing 3 phase condenser
on roof to single phase condenser?

[AcDOCnTRAINING]

Change voltage or system?

[ProgressiveAir]

Is it as simple as changing the voltage to accommodate
the new 1phase unit? Someone told me this can only
be done if the current 3phase unit has a particular voltage.

Don't recall what the voltage number was, but he claimed
not all voltages could be simply switched to phase 1. I'm
trying to confirm if thats true.

[willf650]

It would generally be as simple as changing out the breaker and disconnect for single phase. Chances are though if your replacing a three phase piece of equipment with a single phase one of the same size the existing wire and circuit ampacity would not be enough. As far as different voltages generally if you three phase service you would have 208v phase to phase where as a single phase service would have 240v. Since most equipment is 208/240 this isn't an issue. The exception to this rule would be a building with a 3 phase 240v delta service.

480v is the same voltage regaurdless of single or three phase

[sparks]

Could anything be done to change out an existing 3 phase condenser
on roof to single phase condenser?


I agree with willf650.

Why did you order the wrong one??:eek::eek:

[snipe70e]

Any two legs of a 3hree phase system will yield single phase of the same voltage. Would not matter if it is Y or delta. But remember with a delta there is no neutral.

The only system that could give you problems is a 240 vac with a high leg. I can not advise on a high leg system.

[lipsoffurry]

Did you quote a single phase condensor? Just use the proper voltage and number of phases. Why short cut your customer?

[referteacher]

Since this is a "Commercial" forum, there is a distinct possibility your three-phase could be 460.

If you want to single phase that, you're looking at 277 volt equipment.

[ProgressiveAir]

lips - didnt quote or short anything.
The person called about a particular condenser that is 1 phase.
Their current condenser is 3phase on the roof. Trying
to figure out if it can be done.

sparKs- didn't order anything. we looKed at site, and our now
doing our hw.

will - just to complicate things I would have to put 2 1phase units
into the place of a single 3 phase unit to equal the current 3 phase
tonnage.

[willf650]

Any two legs of a 3hree phase system will yield single phase of the same voltage. Would not matter if it is Y or delta. But remember with a delta there is no neutral.

The only system that could give you problems is a 240 vac with a high leg. I can not advise on a high leg system.

A 240v service with a high leg comes from a delta tapped transformer. This is what I meant by 240v 3 phase delta service. A delta transformer can have a neutral but aside from a service generally doesn't. One of the windings is center tapped for a neutral. That why two phases have 120v to neutral and the third is the high leg. Any two phases of such a service will still yield 240v to each other but the high leg will yield 200+ volts to ground/neutral.

[willf650]

lips - didnt quote or short anything.
The person called about a particular condenser that is 1 phase.
Their current condenser is 3phase on the roof. Trying
to figure out if it can be done.

sparKs- didn't order anything. we looKed at site, and our now
doing our hw.

will - just to complicate things I would have to put 2 1phase units
into the place of a single 3 phase unit to equal the current 3 phase
tonnage.


Your wire size will not be enough for both. Your gona have to pay for atleast one new circuit. You "should" be able to convert the existing circuit to single phase to power one of the units. You need to check the wire size.

[sparks]

sparKs- didn't order anything. we looKed at site, and our now
doing our hw.


Gotcha, but I had to ask.

Where I work, thats the only time I get those kinds of questions.

[snipe70e]

Since this is a "Commercial" forum, there is a distinct possibility your three-phase could be 460.

If you want to single phase that, you're looking at 277 volt equipment.


Single phase of 460 is one hot to neutraql 277 volts. two hots 460

[ProgressiveAir]

Thanks guys.
Sounds like this might be possible, so I'll look a bit
deeper into it.

[skippie_8200]

if you draw more voltage off one lag then the others you will put your phases out of phase. if you are going to single phase off of three phase

[skippie_8200]

if you draw more voltage off one lag then the others you will put your phases out of phase. if you are going to single phase off of three phaseso what that

[troyorr]

Get the electrical requirements for the equipment you are considering, give them to an ELECTRICIAN and have an ELECTRICIAN evaluate what is currently thereto see what needs to be done to make it work. Have them price running power from the power source to the disconnects.

[Bill Tappin]

Why change out from three phase? It's more efficient, the unit dosen't use starting or running components. Also 480v is not a single phase voltage.

[willf650]

Why change out from three phase? It's more efficient, the unit dosen't use starting or running components. Also 480v is not a single phase voltage.

There is equipment is 480v single phase and it is a single phase voltage. Look at all the small blower motors and condenser fan motors out there. The units are 480v three phase but many of these small motors are 480v single phase. Granted a complete piece of 480v single phase equipment is not that previlent but it is out there. The term single phase doesn't necessarily mean one conducter and a neutral.

[desertdweller]

If you replace 1 three phase with 2 single phase you are going to put the whole panel out of balance not to mention that the amperage will increase per unit.

[berg2666]

[QUOTE=ProgressiveAir;1821883]lips - didnt quote or short anything.
The person called about a particular condenser that is 1 phase.
Their current condenser is 3phase on the roof. Trying
to figure out if it can be done.



SO the customer gots a better price on a piece of equipment and wants you to install what he has?

[Airmechanical]

yes it can be done, modifications will need to be made to breakers and incoming wire size!

since you are asking theses questions you better get an electrician:eek:



.

[beenthere]

Is the 3 phase condenser a 2 stage or single stage.
You said you'll need 2 single phase to do teh job the 1- 3 phase is doing.
So are there 2 line sets, or are you going to hook one line set to 2 condensers.
How much more will running a new line set cost.
Will the main panel box have to be upgraded to handle the load.

Lots to look at before telling the owner it can be done.