Heating, Air Conditioning, Fridge, HVAC/noisey air handler

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Question
In May we had a Nordyne IQ Drive variable speed system installed (heat pump model #FT4B1-048K, air handler model # B6VMAI 48K-C) with all new duct work.  The air handler sits in the middle of our home which our living area is centered around it.  The air handler sits on an insulated wood box with 2 return vents at the bottom.

Problem #1:  When the system ramps up to higher blower speeds it sounds like we are in a wind tunnel, when ramping down there is a high pitched whining noise, low speeds sound tolerable.  In summer, this  cycles about 4-5 times an hour.  Complete off time is about 20-30 minutes.

Problem # 2:  There is no ramping up, when the air handler is off and comes back on, it is at high fan speeds, and there is no ramping up.

Problem #3:  In the Florida summer, humidity averages 60% in the house.

I have contacted the installation company and they have tried to remedy these issues to no avail.  Finally, they have admitted this is not right and have agreed to replace the system with another brand.

Question #1.  Do all variable speed air handlers tend to be loud at the higher blower speeds?  

Question # 2.  We have a 4 ton system, the company insists this is the correct size and a 3 ton would not cool enough.  Our home is only 1752 sq.   They said they have done a manual J calculation and it came out we needed 3 Ĺ tons, so they upped it to 4.  Is that oversized?  Would a 3 ton cool enough and have better humidity control?

Question #3.  Any suggestions on what brand AC system has a quiet air handler?  Iím looking at the Carrier Infinity line.

Thank you for any help with this.

Brandy

Answer
I decided to cut and paste, should make it easier to answer this way.


Problem #1:  When the system ramps up to higher blower speeds it sounds like we are in a wind tunnel, when ramping down there is a high pitched whining noise, low speeds sound tolerable.  In summer, this  cycles about 4-5 times an hour.  Complete off time is about 20-30 minutes.
  The wind tunnel sound is likely due to improperly sized ducts and/or returns.  When the ducts are too small, the air moves faster to maintain the proper amount of air flow.  This causes noise.  The A/H are insulated so it should not produce much noise at all.  The A/H is designed with the velocity of the air in mind so it does not make excessive noise.  Velocity though the A/H is also important for proper heat transfer though the coil.

Problem # 2:  There is no ramping up, when the air handler is off and comes back on, it is at high fan speeds, and there is no ramping up.  I do not know without looking at the unit.
   

Problem #3:  In the Florida summer, humidity averages 60% in the house.
    Normal range is 40-60% for indoor air standards.

I have contacted the installation company and they have tried to remedy these issues to no avail.  Finally, they have admitted this is not right and have agreed to replace the system with another brand.

Question #1.  Do all variable speed air handlers tend to be loud at the higher blower speeds?  
  See the answer to the question above...  The problem is not the A/H.

Question # 2.  We have a 4 ton system, the company insists this is the correct size and a 3 ton would not cool enough.  Our home is only 1752 sq.   They said they have done a manual J calculation and it came out we needed 3 Ĺ tons, so they upped it to 4.  Is that oversized?  Would a 3 ton cool enough and have better humidity control?
   A smaller system is going to run longer and dehumidify better. Bigger is NOT better. I live in the SE US in a  2400 sqft home which has a 4 ton unit.  I did not size the unit, the builder did.  I have not had any cooling or humidity issues.  Normal design is 400 cfm/ton and 400-600 sq ft/per ton.  I am not sure what went into the calculations, but you are better off making improvements to the house rather then making the unit bigger.  It will save you in the long run.  If your old unit was a 3 ton, then I would have gone back to the 3 ton or went up no more then .5 ton.  

Question #3.  Any suggestions on what brand AC system has a quiet air handler?  Iím looking at the Carrier Infinity line.  All brands are the same in the amount of air they have to move for each ton of A/C.  See answers above.  I do like the Nordyne product line.  I find most issues with a/c units are normally caused by the installer, not the manufacture.

I think before you do anything else is to call another company in to find out what is going on before changing the unit.  You may have been done wrong here by the installer and what they are willing to do may not fix the problem.  In order to remedy a problem, the problem has to first be determined.  It does not appear they can determine what the problem is.  Their solution may not be a remedy at this point.

Craig
achelpguy@gmail.com  

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Craig HVAC Expert

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I have been in the HVAC field for the past 18 years. I can help with most HVAC questions. I work on commerical buildings for the most part, and have yet to find anything I could not troubleshoot and repair, when repairable. I work on small 1 ton units to a 2500 ton chiller. Troubleshoot air flow, elect, and control problems. I attend regular classes to keep up with the latest and greatest.

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I work on commerical sites, hospitals, gov't buildings. I can troubleshoot just about anything in the HVAC business.

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5 years trade school, VFD training classes, Liebert factory training, some York and Trane factory training.

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