Fan speeds on new HVAC units

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Old 10-07-17, 04:09 PM
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Fan speeds on new HVAC units

I had new 300 CFM HVAC units installed in my apartment. FXY Vertical Cabinet Series | IEC International Environmental
The building paid half and I paid half.
From the beginning I noticed the bedroom unit blowing much more forcefully and noisily than the living room unit. It is very uncomfortable, and basically unusable - the room becomes so chilly that it must be turned off the minute it is turned on and the air flow feels like sitting (or sleeping) in a wind. The management are insisting that there is no problem.
I used an anemometer to measure the actual fan speed. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
The living room unit seems to blow between 255-275 Ft/min while the bedroom unit blows between 295-314 Ft/min.
I plan to present these measurements to the building management. Is there a standard for high, medium and low fan speeds on the kind of units I have?
Many thanks.
 
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Old 10-07-17, 04:14 PM
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There are no specs for CFM vs fan speed.

Are they both identical units..... same exact cooling spec/size ?

They have three speed motors and since you are getting your cooling from a chilled water coil..... the speed can be reduced with no adverse effects.
 
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Old 10-07-17, 04:21 PM
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Units are identical.
Not sure what you mean by "the speed can be reduced with no adverse effects."
 
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Old 10-07-17, 04:28 PM
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With a standard A/C unit and compressor.... you cannot always slow the blower speed down due to coil freeze ups.

I was looking further into the unit you posted. Some have variable speed motors that can be reset. Some have changeable taps for speed selection. All model number dependent.
 
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Old 10-07-17, 05:10 PM
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Thanks.
My guess is that motor on this one cannot be reset - I've been complaining about it for a month.
They've offered two possible solutions:
- a 200 CFM unit, although this size was was recommended by the installer. Bedroom is 13x16, 8' high ceilings, east-facing windows
- a variable speed switch, which I'm told by this board could reduce motor life and operate with more noise.

I'm asking for a replacement. I'm also suspicious of it because it was delivered with the door banged in and the bottom flange bowed. They replaced the door, but now that I'm having this problem I have to wonder if this was some sort of refurbished unit or factory second.
 
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Old 10-07-17, 05:30 PM
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See if you can find the model number on it for me.
 
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Old 10-07-17, 06:14 PM
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I'll try to look behind the doors tomorrow for the model #. Can also try installer, although they're not terribly pleased with me at the moment.
Not sure if any of this means anything.
C. Fans:
1. Fans shall be direct-drive, double-width fan wheels with forward-curved blades.
2. Blower wheels shall be statically and dynamically balanced.
3. Scrolls and fan wheels shall be constructed of galvanized steel.
4. Shall be easily removable.
D. Motors:
1. Motors shall be 3 speed, single phase, 60 Hz permanent split capacitor type for 115 V (208 V, 230
V, or 277 V), permanently lubricated, with sleeve bearings.
2. Motors shall be equipped with quick connect electrical plugs.
3. Motors shall have thermal overload protection with automatic reset.
 
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Old 10-07-17, 07:00 PM
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The formula for CFM with a known FPM is length x width ( of the opening) / 144 x FPM = CFM.

The issue with this is you are too close to the blower with that application.

You could try to traverse the opening to gather the various FPM readings and divide by the number of readings to get a more accurate measurement of FPM for your final calculation. This will still not be as accurate as a balometer.
 
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Old 10-09-17, 10:03 AM
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Thanks for response, Houston 204.
I need information to present to management about the excessive airflow in one of the units in my apartment.
If you have any guidance or advice I would be very grateful.
(Balometer would cost $1,542 - not practical for this purpose.)
 
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Old 10-10-17, 11:43 AM
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Hi PJmax,
These are the numbers I was able to find on the unit. Hope helps . . . Many thanks.
Name:  HVAC Motor Unit #.jpg
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Name:  HVAC Fan Unit #.jpg
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