Had a new Performance series Carrier Heat Pump, HP25 model, with a new variable speed Carrier 5 ton air handler dialed down to 3 ton air flow in a 1750 sq.ft. 2 story home. It performs very nicely except for one thing. It's TERRIBLY NOISY!!! In fact, the outdoor unit is as noisy or even louder then the old Day & Night unit it replaced. Ironically, of the units we evaluated, the DB rating was the lowest on this unit and that was an important consideration. Startup in heat mode is raucous and the outdoor unit fan has a humming pitch that resonates through the home. I've yet to contact the vendor/installer but I'm posting here for some feedback. Especially from you pros. Yes, I expect some noise. I can't believe this is normal however. Any advice is welcome. Particularly whether you think the noise factor is a legitimate replacement/repair complaint.