Do you have a two speed system? You'll normally use the low speed in summer for better dehumidification and the higher speed in winter for more rapid heating. Yes, soft furnishings will diminish the air noise somewhat. Are you listening close to a return duct? Often times, a too small return duct can be quite loud. I'm assuming that the Manual J that was performed on you home spec'd the size and number of ducts for optimum performance, but additional sound insulation beyond simple insulated ductwork is not part of a standard install. Do check the figures to see if they installed what was calculated.

Thanks, Hollysprings. No, this is not close to a return duct, but coming from the floor registers into the room. They did perform a Man J to size the system and I have asked for those numbers. What is your definition of "simple insulated ductwork"? There is no insulation on the outside of the galvanized ducts; should there be? The installation manual does mention insulating the first five feet and installing vanes and 90 degree bends. Thanks for your input and advice.

You should not hear load rushing noises from the vents even in an empty house. The man J won't really help, the Manual D dictates duct sizes. If the noise is too much, then the air flow is too much for the duct and registers. Duct work costs money and it isn't so much a shoddy install just a cost effective (or cheap) one.

So ask for a manual D - that is what you really want. And just try to get more ductwork installed - but you might have to pay for it. Also, the registers can be changed out for quieter ones. We have wood ones on our floor that are very quiet and we had replaced 2 on our ceiling that don't adjust but are quieter.

I just stayed in a 1986 house with the noisiest airflow - it was really unbelievable. So don't think this is a new problem.

Just about everything sounds louder in an empty house.

Forced hot air systems are almost never perfectly quiet, but the sound should still be very minimal.

Thanks for the response. We are meeting with the builder and HVAC sub tomorrow and hopefully it will get resolved (without costing us more money, lol!).

The problem is how many HVAC systems have you listened for in vacant houses?

Furnishings tend to soak up noise pretty well.

David - The main supply duct is 8 X 10 inch galvanized and then the runs are 6-inch galvanized tubes. They did come in and made some adjustments and have added some insulation to the outside if the tube pipe. It is better but I am thinking the lining/insulation should go on the inside or is it all about velocity and size, so maybe a bigger duct size for the run? Did you buy a certain type of wood register or is there just one basic model?

Brickeyee - No, I have not listened to many vacant house systems, but I'm having trouble imagining a dining table, sofa, an area rug, and two chairs soaking up a lot of noise. Am I being unrealistic in thinking that if I am sitting in my chair reading without the TV on that I should not be hearing rumbling from the HVAC or whistling/air rushing noises from the registers?

"an area rug, and two chairs soaking up a lot of noise."

These will soak up a LOT of noise.

Whistling is a problem indicator. Something is restricting flow and increasing the flow speed to make the high frequency sound.
A we designed a system will have a low level of essentially 'white' noise. A gentle rushing sound at low amplitude.

You can often still notice it if you are trying to listen for the unit coming on and switching off.

My new house has same loud problem. I have a 3 zone system. When 1 zone alone comes on (heat or a/c), the air volume noise is tremendous-like very heavy rain. In one particular zone, each register (ceiling) makes a loud pulsating noise in addition to the loud air noise.

My house is fully furnished-builder says this is normal. So, I too am unhappy, but do not know what else to do!

I thought I was the only one! Everyone thought I was crazy when I mentioned how loud the air was coming out of the floor vents. I think it's the wood covers, which I've never had before. They had to take them off to do something with the floor, and the air came on and it was quiet.

but I am thinking the lining/insulation should go on the inside

That makes Joe Lstiburek's list of
Top 10 Dumb Things to do in the South. And, unless you're in the far north, it's still the South a few months of the year in other climates as well.

worthy wrote "That makes Joe Lstiburek's list of
Top 10 Dumb Things to do in the South."

And therein lies my dilemma as the equipment manufacturer and many other engineers recommend lining the first five feet of the duct for noise attenuation.

Lining the inside of any ducting makes about as much sense as using plastic visquine lined flex ducting. The liner deteriorates causing all kinds of "goonies" floating through your air.