I have a double tray ceiling with the top tray being about 10 ft high, how high do I hang the ceiling fan.

Also, I have a vaulted tray in the den with the peak about 12 ft. The fan is mounted about 8 ft level with the original ceiling... is this the correct height? Thanks

Most fans will have recommendations on the box or in the instructions. The size of the blade will partially determine the best height. There is no code on this.

As always, check your local codes, but building codes generally require fan blades to be seven feet above floor.

Can you give us a link or direct quote regarding that height?

They are both 52" standard sized blades. I had a few people tell me they thought they were mounted too low. The blade height on both fans is about 8'.

Here are my recommendations:

Frequently asked ceiling fan questions - Ceiling Fans N More

The fan on the 12' ceiling would take a 2-2.5' downrod, which would put it at around 3' off the ceiling. Your fan is 4' off the ceiling, so I would mount it a bit higher myself. But if it doesn't look too low for you it won't hurt anything.

Same thing on the 10' ceiling-- I'd mount it maybe 6" higher but it's not a big deal at all.

Some fans do have specific mounting instructions from the manufacturer. However most residential manufacturers instruct you to mount the blades 8' from the floor regardless of ceiling height and THAT isn't correct.