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Will a 240v window air conditioner run OK on 208V? #203202 09/14/11 12:52 PM
Joined: Jan 2005
Posts: 91
H
Helectric Offline OP
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Any thoughts or experience with this?

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Re: Will a 240v window air conditioner run OK on 208V? [Re: Helectric] #203203 09/14/11 01:17 PM
Joined: Jul 2004
Posts: 9,439
G
gfretwell Offline
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My bet is no but the answer will be on the label.


Greg Fretwell
Re: Will a 240v window air conditioner run OK on 208V? [Re: Helectric] #203205 09/14/11 01:46 PM
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Posts: 5,316
renosteinke Offline
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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.

Re: Will a 240v window air conditioner run OK on 2 [Re: Helectric] #203210 09/14/11 02:47 PM
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wa2ise Offline
Member
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.

Re: Will a 240v window air conditioner run OK on 2 [Re: Helectric] #203211 09/14/11 06:05 PM
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T
Tesla Offline
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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.


Tesla
Re: Will a 240v window air conditioner run OK on 2 [Re: Tesla] #203213 09/14/11 06:40 PM
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Vindiceptor Offline
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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.

Last edited by Vindiceptor; 09/14/11 06:45 PM.
Re: Will a 240v window air conditioner run OK on 2 [Re: Helectric] #203214 09/14/11 07:08 PM
Joined: Apr 2002
Posts: 7,133
HotLine1 Offline
Member
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.



John
Re: Will a 240v window air conditioner run OK on 2 [Re: Helectric] #203216 09/14/11 08:35 PM
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Posts: 1,273
T
Tesla Offline
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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.


Last edited by Tesla; 09/14/11 08:37 PM.

Tesla
Re: Will a 240v window air conditioner run OK on 2 [Re: Helectric] #203217 09/14/11 09:58 PM
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gfretwell Offline
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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.


Greg Fretwell
Re: Will a 240v window air conditioner run OK on 2 [Re: Helectric] #203221 09/15/11 01:26 AM
Joined: Mar 2004
Posts: 947
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twh Offline
Member
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.

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