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Any thoughts or experience with this?
My bet is no but the answer will be on the label.
If the nameplate say 240 .... no, it won't run properly.

If the nameplate REALLY says 230, you can run it at exactly 208. Any voltage drop at all and you're SOL.

If it says 220, you're good to go.
In theory, a boost transformer would solve the problem, by raising the 208V to 240V. Something like this place (no affiliation, others may have better product) http://www.transformeronline.com/buckboost.htm

Being code may be an issue.
I'm unaware of ANY recent HVAC equipment whose motors couldn't tolerate 200-230 nominal, delivered voltages.

More current will be drawn at the reduced voltage.

The big issue for many HVAC systems is not the motor -- but the control power transformer.

Many are multi-tap -- in which case re-tapping would be most wise.

Unlike the motor, the control logic is pretty finely dialed in.
Originally Posted by Tesla
I'm unaware of ANY recent HVAC equipment whose motors couldn't tolerate 200-230 nominal, delivered voltages.

More current will be drawn at the reduced voltage.

The big issue for many HVAC systems is not the motor -- but the control power transformer.

Many are multi-tap -- in which case re-tapping would be most wise.

Unlike the motor, the control logic is pretty finely dialed in.


230 rated single phase motors will run at 208 volts, but will probably not last long (more than a few weeks or months) before they burn up.

I'd also question whether a 'window' unit will have any control transformer multi-tap ability, it might though, it seems some of the newer units are dual rated.
Just my opinion, but...why not just get a window unit that is rated for nominal 208 volts?

Yes, you can install a buck-boost transformer onto the AC circuit back by the panel, but IMHO the labor and materials will probably be $$$ more than another AC; unless we are talking about a really 'big' window unit.

230 rated single phase motors will run at 208 volts, but will probably not last long (more than a few weeks or months) before they burn up.

Virtually all small motors made in the last thirty years will ENTIRELY tolerate 200-230 VAC nominal -- its even on their name-plate.

You have to get into larger ( industrial ) sizes before it's an issue.

And, yes, I've installed 240VAC 1 phase HVAC units where only 208VAC power was available. Six years later the units were still running strong.

The HVAC industry has standards -- one of which is to make it possible to run their equipment at both voltages.

There are NO END of apartments out their receiving two legs of 208Y120 power. Ditto for small businesses.

It is in the nature of small hermetic A/C systems for them to operate entirely surrounded by refrigerant -- and to actively reject their heat to the outside.

Their motors can take it, and take it, and take it.

I just looked a couple up on the internet (LG and Frigidaire) they say 230/208v.

The real answer is going to be on the nameplate of the one in question but it looks like Tesla is right on.
I'm with Tesla on this - but I wouldn't even look for taps on a window AC, if they have a transformer. The motor has overload protection and undervoltage probably won't hurt the controls.
I've installed them on three phase. Only problem is operator error
To clarify...

240VAC is the nominal DELIVERED voltage

230VAC is the nominal AVAILABLE voltage at the motor

208VAC is the nominal DELIVERED voltage ( 208Y120 )

200VAC is the nominal AVAILABLE voltage at the motor

---

You will see a CONSTANT stream of cross confusion ...

240/208 is the same as 230/200

One is the nominal voltage supplied

The other is the nominal voltage available at the pecker head / motor tap.

I hope this helps the apprentices.

---

A 230 VAC motor is ASSUMED to connect to 240 VAC supply....

A 200 VAC motor is ASSUMED to connect to 208 VAC supply.

ALL voltages are NOMINAL ... and change with loading.

A TOTALLY unloaded motor will climb up the voltage towards parity.

I.E. no load voltages = supplied voltages.

HUGELY stressing motors draw down the local voltage -- and pull in current like crazy.

Until their 'heaters' pop.

This is when the draw is so huge that the windings are in danger.

Heaters are ANALOGS to the dynamics of the motor.

They are specifically engineered to 'pop' BEFORE the windings are damaged.

I'd NEVER install a motor without such thermal protection.

MOST 'small' ( less than one horse-power ) motors have INTEGRAL thermal protection.

Note this when you're planning HVAC disconnects....

MANY small units need only a motor rated switch... !

The cost savings can be DRASTIC...

I was a foreman for a top 25 contractor.

They changed their disco procedure AFTER my re-analysis.

They cut their costs 60% at a stroke.

Such savings infuriated my boss.

So much for perfection.

Why was he infuriated?
Incompetent 'managers' ( out and out Gonnabbees ) fear and hate talent.

My first PM on the job ( eleven months long ) tried every nasty trick in the book to get me to quit. When he informed the Superintendent that he'd replace me with a 'Real' foreman -- my buddy freaked out -- and applied enough pressure to have my PM canned within 72 hours.

Months later, I was working solo, kicking out production at a higher tempo than my former five apprentices could perform. I simply told the Super, "I'm a one-man crew."

Once the 'shell' was complete the job transitioned to a custom build-out -- and a fresh contract. Again the big man made an attempt to move me out of the way -- blocked by the Super and his PM. By this time I'd won over even the office crowd -- whose HQ was just blocks away -- and this was their showpiece project. ( It got some industry award for tilt-ups -- their specialty. )

I was tasked with ANOTHER Gonnabbee PM -- after his foul-ups on this one job -- the Company's Number One Customer had him fired, too. This is the fellow who was infuriated.

His role was to be the customer's favorite -- instead of me. He didn't have a chance -- he couldn't pull a rabbit out a hat -- and become the Super's alter ego on the job site.

Typical example: he's on the roof -- and a visitor needs to meet/talk -- having found me -- I'd just speed dial the Super -- and hand over my phone. It was painless for me -- and quite the step saver for the Super.

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