lower the fan speed of a strong AC


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Old 09-17-08, 01:33 PM
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lower the fan speed of a strong AC

Hi all,

I bought a new apartment with two bed rooms. The apartment is not big and contains a Central air conditioning. The AC uses 44,500 BTU for cooling and 50,000 BTU for warming. It is definitely too strong for my apartment. What bothers me the most is the fact that even if I put the FAN on its lower speed, it is still very strong and even hanged lamps are moving. Is there any way to lower the fan speed?

Thanks a lot

Gil
 
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Old 09-17-08, 02:08 PM
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There are limits to reducing airflow per ton of cooling

You could use a more restrictive filter that would increase the pressure drop & reduce the airflow.

However, there are limits to reducing the airflow as that could cause the evaporator to ice over causing liquid slugging of the compressor.

Do not get the airflow below 325-CFM per ton of cooling!
That could easily be too low an airflow if there is a light load on the cooling coil & low outdoor temps!

The condenser is probably a larger tonnage than your home needs. I would have a manual J heat-gain calc done, or do one yourself.

Do everything that's cost effective to reduce the heat-gain, then downsize the equipment accordingly.
 
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Old 09-18-08, 12:15 AM
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Call a technician

Thanks a lot

I'll call an air condition technician and consult it with him.

Gil
 
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Old 09-18-08, 02:09 PM
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Hi,

I've called two different technicians and they both said that it is imposible :-(

Thanks
 
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Old 09-18-08, 05:35 PM
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I'd say you haven't found anyone who knows what they are doing. Tech needs to come and look. A good Tech knows nothing is impossible.

HAve you checked to ensure that all supply grills are open?
 
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Old 09-20-08, 02:40 AM
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How do I do that?
I do not know what is supply grills.

Thanks
 
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Old 09-20-08, 05:37 AM
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with a sheet of paper putting it at the grill it will blow out the paper(1 or 2 grills per room)....then the return most likely is 1 big grill near the air handler below the stat location or louvered doors into the unit your filter mounting area is all the air back to the unit.rarely see a return per room they use the hallway as the air back from all the rooms too expensive to install return ducts and space limitations.you need to have the same amount of air discharging out of all the grills,a suggestion not the best solution would be to tap the supply duct and run a flex pipe back to the return with a manual damper to dump some of that air (if tapped into the return) as far away from the air handler the better the mixing with the house return. take the filter size it is,and block 1/4 to 1/2 of it with a piece of cardboard if you restrict the air returning it will change the discharge air try any of these (temporary fix to see a change)..the final would be to have somebody change the motor to the lower speeds with different RPM rating.bypassing air around or blocking the return is limited in keeping the unit conditioning with the cooling (icing up) or heating (tripping the hi-limit).if the return is ducted into the furnace the quick test would throw up a sheet a paper on the grill in the hall and then another....do this air adjustments with fan ON only no cooling or heating running.
 
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Old 09-20-08, 09:38 AM
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It just blows too hard

What they are saying is to make sure everything is open and that all the air can get out of every available opening.
After that you may want to investigate upsizing the supply taps (air openings in your system) or adding more taps to your system.
The only problem is that I haven't heard you say anything about being uncomfortable so that tells me that you are probably oversized which creates a whole other host of problems.
 
 

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