If the ceiling heights are 8-9 feet, then installing the vents in the floor are fine. In the winter you want the heat to rise from the floor and mix with the room air. In the summer cool air near the floor works well. The two feet of air near the ceiling may be a 1-2 degrees warmer, but you really don't notice it unless your are standing on a ladder.

If you have some vaulted ceiling (12-16 feet) then you want vents near the ceiling and the floor. Installing a ceiling fan will help.

Will you have access to natural gas? I am curious why you want to install hydronic coil. Are you worried a forced hot air system will cause the air to be dry in the winter?

This is helpful, thank you. All of the ceilings will be 8ft with the exception of the vaulted living room. The reason for the coil is that the air may be too dry like you said. And yes we will habe access to natural gas.

Outlets are placed in the ceiling if the house has an attic

That is true if the equipment is installed the attic, which in my opinion is the worst possible place to install HVAC in a house.

In the New York area most houses have attics and basements. The standard practice is to install the equipment is the basement and run the ducts up to the floor of the top level. Even houses built on slabs will usually have a utility closet on the first floor.

Mike...we have few basements in California...but you have our share of earth quakes here & running in the wall ducts is frowned upon here for safety reasons as cutting out the rim and top plates to run duct work takes away from the structures ability to hold up in the next earth quake Agreed units in the attic are a pita to work on 130 degree up there

I have my Verano climaconvectors and they work for me perfectly!