I'm no HVAC expert, but have a heat pump and the fan draws the air from the sides, through the coils and out the top..
I think having the air going in the top and out through the coils would cause dirt and trash to accumulate in the inexcessable inside of the coils, while in the other direction, this accumulation would be on the outside where it could be cleaned off. (I hose mine off each season)..
My experience and opinion. FWIW.
Steve
Im no pro , but Ive always seen them blow up.
I'm replacing a condensor fan, fan motor and capacitor on a five ton packaged (not split) heat pump. The unit has a 1/2 hp, dual rotation, single speed, 1075 rpm motor with a 22" dia fan with 35 degree pitch angle. Book says this is a proper fan/motor matchup.
The motor rotation and fan installation is set up to draw air into the top grill across the motor which hangs from the grill in about an eight inch deep fan housing, with the fan blade below the motor and then across the coils from the inside out. Coils are set up on two adjacent sides of the condensor coil box.
A friend told me he thought you always drew in from the bottom/sides and out the top. I wouldn't necessarily question what I currently have except that this fan motor has been replaced once, but by an HVAC service company. I'm assumming they knew what they were doing and did the replacement per factory specs with the rotation and flow in the proper direction.
I have an old installation manual but it does not comment on anything that was set at the factory only hook up wiring. The wiring diagram is to faded to read.
Comments from anyone who has experience with HVAC installations please. Is the flow as currently set correct? Is the flow direction optional? It seems to me you would design with a slight back pressure so that you could make sure you were contacting all the coil surfaces and the way to do that, I would think, is to flow as it is currently installed as described above.
Thanks for any comments.
just because someone in the H/ac business did it does not mean it was done correctly... it should have, but they also hire flakes and let them go by the dozens and hire more.. its all money.. who can bring in the most money and how fast they can do it.
I'd say your friend is correct. The fan creates a slight vacuum behind it. Air will be nearly evenly drawn across the coil surface area for maximum efficiency. If the fan blows into the unit, the direction and velocity of the air will favor one part of the coil better than the other parts = lower efficiency. Also, the heated air will rise and can be drawn back in. It can also be directed back to the unit by nearby objects. The heated air expelled through the top will not likely re-enter the unit. Also, in the winter, the cold air expelled from the top has a less chance of re-entering the unit because of it's higher velocity pushing it away. John
Dual rotation? You mean reversable right?
Not always...old York Doghouses blew in and out..the coils..
Well...95% of the units out there blow up through the coils..but since you have not even posted close to enough information, no one knows.. I will state that if you dont get the fan back on at the right location, your compressor will love you for it...not.
If you draw in the sides and out the top, you're cooperating with the natural flow "heat rises".
You also make it easier to see if the coils are dirty -- cause the dust will be on the outside.
Every condensing unit I've seen, the air sucks in the sides and blows out the top.
Follow up:
I got a factory spec chart and as it turns out it is specified to draw in and exhaust up. The service tech who replaced the motor the last time mounted the blade upside down and left the motor rotation cw. Just goes to show you even the so called pros make mistakes.
I'm sure it makes a difference, however the heat pump operated like that for about four years. Hopefully, I will gain some efficiency by going back the other way.
Actually, there are fewer and fewer real pros...most are $20 an hour flunkies working for the real pros..and thats a shame.
You will...my question tho is...with the fan set screw the way they are, how in hell did he get it back on wrong, unless it was on the end of the motor shaft, and that would have put it far below where it needed to be.
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