Fan rotation summer vs. winter

[referguy123]

Has anyone ever heard of changing the rotation on a condenser fan motor winter vs. summer when using ambient fan cycling? Area where the winter temps can get very low.

If it is not recommended, please expalain why and also what your experience has been....I want to know a little more than just word of mouth B.S. or what a book reads. Thanks.

[chefid]

never heard of that cant really see what the difference would be i imagine that if that was a good thing the factory would set it up that way

[gastech]

Never heard that one. But I do know that Copeland warns against fan cyclers on units w/semi hermetics unless the suction line is wraped around the body.

[OregonYeti]

I also heard that you can control outside temp with your thermostat, if it's a fancy one.

Are you talking about a heat pump? Cooling isn't usually needed when it's cool outside (?) unless it's a bakery or something.

[rocket]

look at at fan blade closely, place it so air blows in your face
note that reversing fan blade causes air to slip off blade, i.e. no air movement
no air flow

what does no air mean

[OregonYeti]

look at at fan blade closely, place it so air blows in your face
note that reversing fan blade causes air to slip off blade, i.e. no air movement
no air flow

what does no air mean

it's flowing in the reverse direction

[Trublshter]

I have never heard of reversing fan blade rotation on a condenser coil under any circumstance. If you did on an a/c or heat pump it would adversely affect the operation of the unit. In mechanical heat mode the outside fan still has to move air across it .

[OregonYeti]

Same here, as far as I know air flow over the coil is optimized in only one direction.

[fire]

Fan blades are designed for one rotation. cw is a totalyy different from ccw. In fact it is the opposite. like left to right , black to white, night and day. Sorry the poet in me is coming out!

[wannafreeze]

I heard about it at this forum a couple of years ago.It had been discussed.

[wannafreeze]

http://www.hvac-talk.com/vbb/showthr...erse+condensor

[TGoodrich]

by reversing the rotation of a condenser fan motor, the fan would push air the opposite way and quite less efficiently due to the cupping shape of the fan blade. your motor would most likely draw less amperage. i have never seen anyone do this, however, if there was any significance to doing this it might be to lengthen the fan cycling time in colder weather. (instead of on and off, on and off.....)
i wouldn't recommend it! I would just increase the differential on the cycling switch

[Special-K]

Shouldn't be necessary with a properly operating low ambient control like a flooded condenser system.

Besides; that practice is just asking for someone to forget to put it back right before the warm season, then you're running the unit with high head and possibly done some damage.

[300 Win Mag]

I would NOT do it. The motor will not run the correct amps and you can burn the motor!

[Dowadudda]

first, i will say reverse air has been done for years on many a refrigerated cases in many many manufacturers offerings. Reverse Air Defrost. Big thing for some time during energy crisis type hype from years past. Works well if a guy knows how to work on them. Kysor, Warren Sherer, Tyler, Hussman. Pulls ambient air in through the honeycombs, completely reverse rotation from normal operation in refrigeration mode.

http://www.patentstorm.us/patents/6116856.html

Now. The concept is there and is a proven fact can be done. But if you think of reversing a condenser fan, you have to ask why you would want to. I think the poster is assuming a reverse of rotation would cause less air flow thus raising head pressure. It would. Because no air would pass, unless. Unless we have a reversing fan blade and motor. Two components needed 1. reversing fan blade and reversing motor. plus relay actuation.

But.

This would not solve the problem. It would push or pull with equal cfm, unless of course you slowed the fan speed down. If you did that, you can forget about reversing, as it is much easier to solve the problem to slow it down.

And for a reefer guy, all this is way too fuggen complicated.

[OregonYeti]

Dow, thx for the info. I can see how a fan with each blade symmetrical would blow the same cfm's either way, but a lot of these fan blades are elongated on the trailing side and obviously meant to go just one direction (?)

[clydemule]

I mostly agree with Dow, expcet that I think when the fan runs backwards it is not equal CFM as to when it runs forward. Depends on the fan I guess.

However, the reduced flow would probably not be enought to get any real head pressure control benefit. Also like Dow said extra controls yada yada.

I like using cardboard and duct tape on the condenser.