Rushing noise in ducts after new heat pump?

pinstripeSeptember 17, 2011

Hello. I posted earlier about replacing my aging heat pump, and the new unit was installed today. I had my old 2.5 ton unit replaced with a 2.5 ton outdoor / 3 ton indoor variable speed. The technician advised this match because of our high humidity and difficulties heating the whole house at one time.

Well the point was to move more air, but it didn't occur to me this would make more noise. When the unit kicks on, there is a rushing or roaring noise as air moves through the ducts and registers. The equipment itself is not that loud, just the ducts. I may have expected too much (everybody told me how silent it would be, compared to the old unit) but honestly, the first time it happened, I thought it was an airplane.

Is this something that can be adjusted by me or the technician? Is it just normal with the larger unit? Or does it indicate I've been sold the wrong system?

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You should be able to turn it down since you said it is variable speed. It probably needs a technician or an expert here to tell you how to do it. Maybe post your airhandler model number to get some advice or wait and make a service call.

The advice given here is never to expect increasing airflow will help with distribution/duct issues. You always have to fix the ductwork and it sounds like you have proven the point.

    Bookmark   September 18, 2011 at 5:54AM
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most of these variable ecm motor will ramp up till static pressure matches the setting, if duct work is too small and cfm is set too high, this motor will consume more energy then what is was designed to do. as last post..put your model and serial up on here.

    Bookmark   September 18, 2011 at 9:54AM
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Thanks for the comments. I am fine asking the technician come make adjustments, I just want to understand what I'm asking for.

The units are Trane 4TWB3030B1000AA / 4TEE3F39A1000AA.

    Bookmark   September 18, 2011 at 7:14PM
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Having an upsized indoor coil (air handler) does not favor humidity removal. Lowering airspeed in cooling will compensate. Seems counter-productive.

    Bookmark   September 19, 2011 at 8:26AM
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CFMs should be set not more than 1000 for a 2 1/2 ton system at the air handler.


    Bookmark   September 19, 2011 at 9:29AM
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I just experimented by turning on the fan, only (without attempting to cool the house) -- whisper quiet. The noise only comes when the unit is conditioning air. Could I be hearing machinery noises coming up through the ducts, as opposed to air rushing?

Not sure if this is relevant, but the supply plenum is shorter than previously, because the new unit is taller.

Thanks for your input.

    Bookmark   September 19, 2011 at 4:30PM
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