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  1. #1
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    HVAC blower speed too high when compressor kicks on, but FAN On is lower speed?

    Help, LOUD (jet engine when cooling my condo) brand new Rheem RBHP-21J07SH2 my air handler was set too high and I changed it to the manufacturers correct setting T3 for high as it was on T5, if I put the thermostat on "FAN ON" the air handler drops to a lower fan speed which seems to be 1/10th the noise, however whenever the compressor is on, the fan is in "high" mode which is forcing air through the vents and is super noisy. The guest room vent sound like a hair dryer is on. Is this wired incorrectly on the installation? My AC guy is in Italy this week and cannot help me.

  2. #2
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    Jan 2014
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    Guessing your guy did not set up your system correctly originally. Hopefully when he comes back from his trip to Italy, he can set up your blower to manufacturer spec. may or may not have issues with possible coil icing if he sets it to low? He needs to check static pressures to manufacturer specifications also.

    Ask him to provide the AHRI number to prove a matched system was installed, unless he gave you the number already.

    Here's the web-site it will show you your SEER and EER on paper.

    https://www.ahridirectory.org/

    Why are you adjusting the fan speed, don't you have a labor warranty? If so doesn't he have someone for coverage when he's away to respond to customers complaint?

  3. #3
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    Feb 2019
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    Thread Starter
    Hi, I'm going to go to the HVAC office on Monday as they are closed today. The air handler is so loud I started looking on Google and it lead me to video's of how to change the speed connection. The manufacturers specs diagram for Rheem 2.5 ton says Low speed T2 and Hi speed T3, it was set at T5. So now when the fan is put ON it's nice and quiet until the compressor kicks and then it's back jet engine speed. Thanks for your help.
    Mike

  4. #4
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    Your Air Handler looks to be up to 3 tons, so guessing the factory setting was for ( T5 ) a 3 ton Air Handler? You having a 2.5 ton OD unit the Installing Contractor is suppose to set it in the field. Just because it's set at a factory setting does not mean your Contractor is not suppose to move it. I'm guessing your not within manufacturer static pressures as is?

    Did your old unit have a up to 3 ton AH or a 2.5 ton AH? If a straight 2.5 ton maybe your ductwork can only handle up to a 2.5 ton system at best. Ductwork is trickey, there is no such thing as one size fits all ductwork. If you do not see a tiny hole in your return and supply side near the AH, chances he never checked static. You can research how to check static.

    Web-site says up to 16 SEER for that AH so if you had a upwards of 16 SEER OD unit and it's a AHRI certified match and your state or local utility company offers rebates your system may apply.

    Here is one site to check: http://www.dsireusa.org/

  5. #5
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    Nov 2008
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    Piney Flats, Tn.
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    chances are they put in a larger unit to cool better.

  6. #6
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    Feb 2019
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    Thread Starter
    [QUOTE=Bazooka Joey;25672080]Your Air Handler looks to be up to 3 tons, so guessing the factory setting was for ( T5 ) a 3 ton Air Handler? You having a 2.5 ton OD unit the Installing Contractor is suppose to set it in the field. Just because it's set at a factory setting does not mean your Contractor is not suppose to move it. I'm guessing your not within manufacturer static pressures as is?

    Did your old unit have a up to 3 ton AH or a 2.5 ton AH? If a straight 2.5 ton maybe your ductwork can only handle up to a 2.5 ton system at best. Ductwork is trickey, there is no such thing as one size fits all ductwork. If you do not see a tiny hole in your return and supply side near the AH, chances he never checked static. You can research how to check static.

    Web-site says up to 16 SEER for that AH so if you had a upwards of 16 SEER OD unit and it's a AHRI certified match and your state or local utility company offers rebates your system may apply.


    Thanks, no rebate for me. Cannot tell if static check, closet to small. I see it says 3 ton on one website as per my model#, which would suck. I changed to the T4 speed and when manually ON it whispers then the condenser kicks on and the Jet Engine continues, must be a screw up. Thanks for your help.

  7. #7
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    Feb 2019
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    Thread Starter
    Bazooka Joey last question,
    In reading the installation instructions which I finally found. "4.3.1 Cooling Mode" When the thermostat calls for cooling, the G terminal on the blower control board is energized which in turn energizes the indoor blower motor. This causes the indoor blower to circulate air through the air handler and duct system during the cooling cycle. The Y terminal on the blower control board is also energized which tells the blower control board to energized the cooling speed on the motor instead of the reduced CFM continuous fan speed." If it's already set at a speed of T4 or T5 how can it go a faster speed during cooling mode?

  8. #8
    Join Date
    Apr 2012
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    Joey's right: Your contractor has provided an air handler good for 2-1/2 and 3 tons. It's delivering 1,000 CFM give or take with Setting 3, 5 gets you 1,250 CFM or so; see page 23. Also of interest is page 19 where Rheem specs ductwork. I would be surprised if the system effectively dehumidifies at 500 CFM/Ton.

    Demand a smaller unit, the 17 will be fine: Around 750 CFM assuming his duct design illustrates the same level of competence.

    He graduated Cum Laude from the HVAC for Dummies course, where he was taught to oversize blowers and set them on "Hi" when he completes the installation.

    Good Luck!

    PS: I see this all the time!

  9. #9
    Join Date
    Apr 2012
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    Millsboro, DE
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    RM:

    Top of 23 tells the installer 360 to 450 CFM/Ton, 720 to 900 CFM.

    Code Violations: System doesn't meet Manufacturer's Installation Instructions (2015 IMC 304.1) and doesn't deliver required airflow (2015 IMC 603.1 - "The Famous 16 Words").

    DB: You're right about more cooling, but I would think there'll be some real fun in about a few months.

  10. #10
    Join Date
    Feb 2019
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    Thread Starter
    ferd1942, when I put it to T3 speed it still jet engine high. This is the issue. Why doesn't the fan slow down to T3 speed instead of always jet engine when cooling mode comes on. It seems the T1 through T5 speed settings are useless.
    Thanks, Mike

  11. #11
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    Aug 2002
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    Southold, NY
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    The noise your hearing if Oversized equipment on Undersized Ducts!

    Now the contractor needs too correct it as best he can. That rarely works out well!

  12. #12
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    Jan 2004
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    Perhaps your ductwork isn't sized large enough for a 2.5 ton.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  13. #13
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    Feb 2019
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    Thread Starter
    How do I lower the speed? That is the question. If the speed tap T1 through T5 does nothing can it just be wired wrong? The speed should be able to be reduced right?

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