3 Phase Package AC unit, run the compressor on a vfd and convert to single Phase.

[D Farms]

I purchased a used 3 phase package AC unit for my home shop. I also recently moved, and when I bought the house, I noticed there where 3 phase power lines very close to the property. I figured it wouldn't be much to have the power company setup a transformer and run 3 phase to my property, however they gave me a ball park estimate of 20,000. Obviously that's way to much, I personally think its a BS price, but maybe there are some hidden costs that I cant account for. Anyways I have a 200 Amp panel, and I have a few 3 phase machines that I want to run. A 1hp Bridgeport, a 3hp lathe, the 5 ton AC, and my big old 30hp Haas HS-1. The Bridgeport and lathe already have VFD's, and I was thinking about getting an American rotary AD rotary phase converter for the Haas.

That just leaves the AC unit. It draws about 15 amps on a 3 phase circuit, I ran it on a 20 amp circuit to test it out before I bought it, and it had no issue at all. When I hooked it up to test I could tell that the only thing using the 3 phase was the compressor. the blower and all other electronics run on single phase 220. I plan to order a VFD to run the compressor, which will be much less expensive than a rotary phased converter. I also dont want to run on the same rotary phase converter as the Haas. When I get a chance Ill tear into and see what size the compressor motor is, and if it really is the only 3 phase component.

Also I live in PHX, so having an AC for the shop goes a long way.

Has anyone done anything like this before.

 

[thermite]

Has anyone done anything like this before.

No.

But I've swapped compressors. Or entire "outside units".

They are "packaged". Affordable. Do not HAVE to even brand-match.

And done all the time by HVAC guru's. Why fight the obviously easier route?

Have a look - I've had decent goods from these folks safely shipped to Virginia:

Alpine Home Air Products: Contractor-grade furnaces, heaters, air conditioners and indoor-air quality products at wholesale prices.

They have competition. LOTS of it! Look around...

 

[D Farms]

Just to clarify, by package unit I mean its like this, everything is inside of one enclosure.

Good info though, I'll keep that in mind. If I dig inside and see that the compressor is easy to swap out, that would be a good option.

 

[thermite]

Just to clarify, by package unit I mean its like this, everything is inside of one enclosure.View attachment 286414

Good info though, I'll keep that in mind. If I dig inside and see that the compressor is easy to swap out, that would be a good option.

Of course it is. All that sheet metal comes right off in large panels.

It was assembled from mass-produced commodity parts, after all.
Not grown from an egg.

Mind if you are not yerself an HVAC "guru" with Refrigerant gear and handling credentials to stay legal, you may find they don't work all that cheaply, and yah shudda just bought a single-phase unit at the outset.

Lots of modern units have a VFD built-in, but they were engineered that way to put it to most efficient use, and effectively so.

These units don't cost enough that I'd waste my time on anything complicated. They cycle constantly all season, so it just creates a maintenance headache.

Could make the MOST sense to peddle it, as-had, to someone who has "mains" 3-Phase already.

Then go and buy something "turnkey" in single-phase so you can get back to doing YOUR "Day Job", sooner.

 

[D Farms]

Perhaps, I only paid $300.

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[Street]

have a think about the $20k install, if you did it would the value of your property go up? by some amount if you happen to sell before you kark it......
ie will it make it more attractive to a potential buyer?

I think 3 phase is a lot more common on commercial equip and when i was younger i was told 3 phase equip is cheaper to run.

Lots of options in 3 phase equip as well.

 

[D Farms]

have a think about the $20k install, if you did it would the value of your property go up? by some amount if you happen to sell before you kark it......
ie will it make it more attractive to a potential buyer?

I think 3 phase is a lot more common on commercial equip and when i was younger i was told 3 phase equip is cheaper to run.

Lots of options in 3 phase equip as well.

I did a bit of research, and it looks like they can basically charge you whatever they want, based on how long you have been a customer, and more importantly how much power you are going to consume and pay for. Basically if you arent going to use the power,or they think you will sell the property they wont give you a good price on the 3 phase, since it wouldn't be worth it for them. I think the best strategy on the 3phase front would be to wait a little while and check again. I also have a big welder and plasma table that would benefit from having a larger service, and Im in the process of building a shop in the back. So maybe once I make some progress on the shop, If I tell them about all of the power the tools need I they might give me a more reasonable price.

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[TDegenhart]

Talk to Wheelieking71. He's in Arizona and has been through this all before.

Tom

 

[thermite]

Perhaps, I only paid $300.

Person can get a hangover cheaply, athlete's foot fungus infection, or even an STD "for free".

Doesn't make any of those a good idea.

VFD's to run AIR HANDLER fans are a special class of low stress, low cost critters.

VFD's to reliably run chronically-cycling COMPRESSORS - air OR refrigerants - are the exact opposite.

Right costly "industrial grade" goods if they are to have any serious durability.

Peddle, trade, or donate this 3-Phase puppy and go look for a good deal on a single-phase rig you can "just run", as-had.

"Personally".. I just keep an eye out for Big Box closeouts as the hot months end, stash the odd "consumable" cheap-as-dirt window-unit 'til the next year, am happy to get a fourth and/or subsequent year - or more - out of 'em, repeat, repeat...

Yer only tryin' to cool a "shop".

Not a high-grade whorehouse, other Official Government office, nor Big Corp Boardroom.

 

[ptsmith]

Thermite, you know you kill threads when you insist that your way is the only way, post after post after post. Carpet bomb a thread until everyone gives up, and the OP never gets the advice they were looking for.

Not intended to piss you off. Just an observation.

 

[D Farms]

I've noted his point. Im still going to try to convert it with the VFD. I already have all of the parts to do it, so no sense in not giving it a go.

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[SomeoneSomewhere]

In many manufacturers' lineups, the heavy duty and light duty drives are the same part number, you just derate the drive one size. Choosing a VFD will depend on the type and size of the compressor in the unit, but it's likely that you will want to size it for a heavy duty VFD, if not a step larger again.

Reciprocating compressors require very high starting torque. Scrolls probably less so.

The higher end drives are usually more about features and controllability than reliability. Higher end drives will usually get you safe-torque-off, closed-loop (encoders) control, (more) fieldbus support, faster reaction to load transients, and higher maximum frequencies when run in vector modes.

 

[thermite]

Thermite, you know you kill threads when you insist that your way is the only way, post after post after post. Carpet bomb a thread until everyone gives up, and the OP never gets the advice they were looking for.

Not intended to piss you off. Just an observation.

"Pissing me off" is above most folk's pay-grade. Too much like work to even get my attention.



It isn't "my way". It's the HVAC // ASHREA industry way. "RTFM".

OP doesn't WANT the professional advice he has already been given.

What he wants is enough amateurs to tell him what he already decided to do is a wise move. Join them if you can.

He wants to put a VFD in harm's way to try to salvage an inappropriate choice?

He will do exactly that.

Watch and see.

 

[D Farms]

Its true Im not doing this by the book. But with that logic, I also shouldn't have bought old 3 phase Machine tools and put VFD's, quick change tool posts and DRO's on them. I Should just go and buy machines that had those features built in from the factory.

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[thermite]

Its true Im not doing this by the book. But with that logic, I also shouldn't have bought old 3 phase Machine tools and put VFD's, quick change tool posts and DRO's on them. I Should just go and buy machines that had those features built in from the factory.

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That may as well compare pigs and moonbeams for all the congruence yer likely to find.

Not at all related to Old Iron.

It's a refrigerent compressor. Not an air compressor.
Air compressers don't ordinarily have a mode where they can "slug".

"For extra credit".. make sure you integrate the prevention of that to your VFD's control loop.

Not HARD. Yah just have to DO it 'coz the VFD doesn't otherwise know or care.

 

[ptsmith]

This video might help a little. It's made by a kid and it's kinda weird, but he is doing what you want to do.

YouTube

 

[SomeoneSomewhere]

If the VFD is being used at fixed frequency aside from a short ramp up, and all the safeties remain in place, it's in no more danger than when connected to the grid. The grid cares about your compressor even less than the VFD.

If you attempt variable capacity, or try to change what's controlling the expansion valve(s), you might need to put a fair bit more thought into this.