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Upside down condenser fan?


Neal Lewis
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Older Westinghouse condenser unit. The fan was drawing air down through the top of the unit and discharging out the side colis. The condenser was a standard configuration; I doubt it was manufactured this way.

The system was cooling the house. What's the implication of the fan installed upside down? The only thing I can think of is that it may not move air as effectively.

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Neal I'm no engineer or mechanic, but if the air flow is backwards doesn't that mean the motor is running in the wrong direction?

I sure haven't heard or seen what you describe. I suppose the air passing thru the coil is what counts anyway, though the direction of flow might not be with the designer's intent.

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The condenser fan on a residential unit is single phase. You can't reverse a single phase motor however, you can order a motor with a cc or ccw rotation looking from the shaft end. To reverse a three phase motor just reverse two of the leads.

I would think that someone installed the wrong motor. I'd advise the client to have the unit looked at by an a/c company.

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Originally posted by Terence McCann

The condenser fan on a residential unit is single phase. You can't reverse a single phase motor however, you can order a motor with a cc or ccw rotation looking from the shaft end.

Huh? Anything from a simple 120v electric drill on up can be reversible. When I sold electrical stuff we stocked a lot of 1/4 - 3/4 HP motors for AC units. Some were dedicated cw or ccw units, but others could be reversed by switching the connectors on two leads left hanging out at the back of the motor.

Brian G.

Whut 'Chu Talkin' 'Bout Willis? [:-bigeyes

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Originally posted by Neal Lewis

Older Westinghouse condenser unit. The fan was drawing air down through the top of the unit and discharging out the side colis. The condenser was a standard configuration; I doubt it was manufactured this way.

I've never seen it configured that way either - and I've seen several old Westinghouse units. Perhaps some clever homeowner didn't like all that air blowing up for some silly homeowner reason and he figured out how to reverse the motor.

The system was cooling the house. What's the implication of the fan installed upside down? The only thing I can think of is that it may not move air as effectively.

I don't know. At this age, efficiency probably isn't really an issue. If it's cooling the house, I'm not sure what there'd be to criticize.

- Jim Katen, Oregon

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Originally posted by Brian G.

Originally posted by Terence McCann

The condenser fan on a residential unit is single phase. You can't reverse a single phase motor however, you can order a motor with a cc or ccw rotation looking from the shaft end.

Huh? Anything from a simple 120v electric drill on up can be reversible. When I sold electrical stuff we stocked a lot of 1/4 - 3/4 HP motors for AC units. Some were dedicated cw or ccw units, but others could be reversed by switching the connectors on two leads left hanging out at the back of the motor.

Brian G.

Whut 'Chu Talkin' 'Bout Willis? [:-bigeyes

Your right about reversible drill motors Brian, my statement was dealing with condenser fan motor replacement (should have put in a qualifier).

I've never seen a single phase condenser fan that had the option of reversing the rotation. When I was running service, and replacing single phase motors, you always had to state direction of rotation, frame size etc. We would rarely go back to the manufacture for direct replacement, they were way more expensive than Sam's motor shop.

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I don't know. At this age, efficiency probably isn't really an issue. If it's cooling the house, I'm not sure what there'd be to criticize.

- Jim Katen, Oregon

I'm with brother Katen. If an old A/C unit is keeping the house cool, leave it alone. If the thing were engineered all wrong, somebody would have said something by now.

My Carrier unit is into its 23rd successful cooling season. I'm afraid to even eyeball it, let alone put a wrench on it.

WJ

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So now we're to "If it works it's OK?" Ungrounded outlets work just fine, are they OK? I don't know the answer to the AC question, I have run into this myself. It seems there must be some reason 99 percent draw air up through the coils. My gues is it was replaced with the wrong motor. I would recommend an AC guy look at it, I wouldnt want to be stuck with the bill when it failed. You know, the first thing the AC guy would say is " the fan is running the wrong way, didn't the home inspector point that out to you? Anybody with any sense would know that. I would have him pay for this repair."

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Originally posted by homnspector

So now we're to "If it works it's OK?" Ungrounded outlets work just fine, are they OK? I don't know the answer to the AC question, I have run into this myself. It seems there must be some reason 99 percent draw air up through the coils. My gues is it was replaced with the wrong motor. I would recommend an AC guy look at it, I wouldn't want to be stuck with the bill when it failed. You know, the first thing the AC guy would say is " the fan is running the wrong way, didn't the home inspector point that out to you? Anybody with any sense would know that. I would have him pay fpr this repair."

The original poster said the unit is old. If it's old, and it's keeping the house cool, and nobody's complaining, I'd call that OK. It's the middle of June. If the thing weren't working OK, it would've been fixed by now.

Re ungrounded receptacles: Last time I checked, NEC said they're OK, as long as they're two-slot receptacles.

Pardon my saying so, but acting on an HI "gues" would do more harm than good. Why would anybody want to wrench on an old A/C unit that's working and keeping the house cool, based on a "gues?" What would the HI report? "I guess there's something wrong. Call an HVAC tech?" In my neck of the woods, that recommendation would cost somebody at least a couple hundred bucks, which is more than an old A/C condenser is worth.

Speaking just for myself, I'd be perfectly comfortable telling an HVAC guy, a seller, a customer or anybody else that I'm in favor of leaving a working unit alone. Spend the service-call money on the next condenser.

WJ

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Phillip,

Don't fret. That's a common misconception. You surely don't have to reverse a motor's rotation to reverse air-flow - you need only change the pitch of the blade. It is intuitive (but wrong) to believe turning a blade upside-down reverses the blade's pitch.

I look forward to the release - August - of Hofstadter's "Masters of Deception". The mind is easily teased into believing wrong things.

Originally posted by Phillip

To everyone,

I was wrong on turning the fan blade over. My mind was on other things. It has been a long week. I will try to only post things that I know that are true.

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I would'nt take that bet, Swampy. Out of a gazillion A/C's inspected, that's a first for me. What if the fan/motor was just replaced the wrong way recently, even though the condenser is old? I would say it's at least worth a telephone call to a HVAC guy, without a service charge.

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Originally posted by Neal Lewis

I would'nt take that bet, Swampy. Out of a gazillion A/C's inspected, that's a first for me. What if the fan/motor was just replaced the wrong way recently, even though the condenser is old? I would say it's at least worth a telephone call to a HVAC guy, without a service charge.

Well, I guess you'll call an HVAC guy. Fine with me. I assumed that when you looked at the thing originally, you would've known a new motor if you saw one.

If I were going to call anybody, it wouldn't be an HVAC guy. My experience with HVAC guys, and tradesfolk in general, is that when it comes to reliable information, they hit well below the Mendoza line.

Manufacturers, on the other hand, make sure they're right before they start offering up answers. I have yet to encounter mfr folklore.

Maybe you could call the mfr and get the info from the horse's mouth.

WJ

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Swamp, you do make a good point about calling an HVAC tech. Sort of a "damned if you do, damned if you don't".

I inspected a home a few months ago and got a 7 degree split on the A/C, I recommended calling HVAC, they came out and said everything was OK, the system was working fine. Needless to say, I got a call from the pissed homeowner demanding I pay the $65 service call. Funny thing is, it was a company that I had called out a bunch of installation problems on other recent jobs. Its all judgement calls I "gues".

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Originally posted by homnspector

Swamp, you do make a good point about calling an HVAC tech. Sort of a "damned if you do, damned if you don't".

I inspected a home a few months ago and got a 7 degree split on the A/C, I recommended calling HVAC, they came out and said everything was OK, the system was working fine. Needless to say, I got a call from the pissed homeowner demanding I pay the $65 service call. Funny thing is, it was a company that I had called out a bunch of installation problems on other recent jobs. Its all judgement calls I "gues".

Well, while we're on the subject: in the last few years that I was doing everyday HI work, I decided that virtually all of my repair recommendations, if implemented, would do more harm than good.

We did a lot of new-house jobs, and we found that that most roofs needed some kind of fix. But the builder would just send the same puddinheads who screwed up the original job, so things only got worse. Same with the brick veneer, same with the concrete, same with the door hangs, the decks, the HVAC, the plumbing, etc.

Seemed to me that new houses were literally going from bad to worse every time somebody touched the house with a tool. I felt that I had to temper each recommendation with a warning about automatic worsening.

So, I just told the customers: I have to tell you to get these things fixed, but at the same time I know you won't get a good outcome. Wait 350 days into the 1-year "warranty," and then evaluate the situation.

It's always something...

WJ

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Originally posted by Terence McCann

I've never seen a single phase condenser fan that had the option of reversing the rotation.

Sorry to so long getting back...busy season (finally). GE and Universal both used to make them, and I would assume still do. It sure saves a lot of stock space on the shelf.

Here's the first one I ran across on a search. Look under "features". http://www.aosmithmotors.com/Products/HeatMaster/

As for this particular instance, I have to agree with the sentiment that an HI would be damned if he did and damed if he didn't. The question then becomes where one wants to be standing if the poop encounters the propeller. It's wrong, so I would have to tell the client it was wrong-but-working and recommend having it corrected. If it was old I might well advise them to just replace it before it fails, but I can't see advising them, in writing, to stick with the backwards-running condenser fan motor. If they decide to ride it till it drops that's fine.

To each his own.

Brian G.

My Job: I Found This, It Ain't Right, Fix It

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