Do you think someone here that has never seen your dwelling can do a better job designing ducts than contractor you have on site? If so you should hire a contractor you can trust before going further.

I was mostly wondering whether it’s a bad decision no matter the house to have hot air coming out near the ceilings. But I stand corrected!

You are correct, hot air tends to rise, and cold air tends to fall. If were my house I would want supply vents to be near the floor level in addtion to ones near the ceiling. Your HVAC engineer might be placing vents near the ceiling only because of cost. I am going to assume your wall of your NYC apartment are built with plaster and lathe.

Ask the engineer if adding some supply vents near the floor level is feasible.

I think the "theoretical" duct placement concern is overblown. In a normal interior space, with properly sized equipment and long cycle runs, air manages to blend. If ducts are both up high and down low, for one of the HVAC functions (heat vs AC), the placement of some will be sub-optimal as that argument goes.

Hot air will rise and cooler air will sink no matter where ducts are and no matter which function is being used.

I have a custom built house with just floor vents, and another in a neighborhood development with just vents in the ceiling or high on walls. Heating and AC work just fine in both without producing hot spots or cold spots.

Edit to add:

In situations like Emily's remodeling project, new duct placement is often the result of deciding the most cost-effective approach that's feasible given the nature of the project. It sounds like a pro is involved and the approach recommended should be assumed to be the result of the pro applying his or her knowledge and experience. Consistent with project needs, expectations and budget constraints.

Water source heat pumps can be very efficient. What is the source of water? Are they being completely replaced by air source heat pumps?

Your concern about register placement is correct.

However, where do you place your value, in comfort, efficiency or up front project cost?

IMPO

SR

The HVAC has to meet requirements for the permit and inspection. Ask the building inspector for info.

The requirements to meet current building code don't require or guarantee control of indoor relative humidity nor occupant comfort. Accordingly, meeting code requirements is not a good gauge of HVAC system performance. The building official or building inspector aren't the best resources.

Conditioning of an indoor space via supplies located in the ceiling doesn't mean that efficiency or comfort will be compromised. It does require adequate mixing of the air volume which is a function of the location of the supplies, the returns, and the air velocity. If you have questions, ask your HVAC designer or engineer.

" Water source heat pumps can be very efficient. What is the source of water? Are they being completely replaced by air source heat pumps? "

I thought you were in the HVAC business?

Emily's explanation was quite clear. I'm not in the business and understood immediately she was talking about a building with a conditioned water loop the equipment in each apartment would connect to.

Emily, this guy has a history of making recommendations that don't always or necessarily consider the practicalities of feasibility or reasonable spending budgets.

Elmer J Fudd is the nasty troll on this forum that changes his handle literally from one Loonie-Tune character to another to mask his on-line persona when necessary to keep posting.

He is incapable of contributing new or original content due to his lack of knowledge or training in the HVAC field. His field is shoe salesman, a bitter ‘Old Sole’ as can be determined by reading through his many posts. I wouldn’t bother; it’s a waste of time.

IMPO

SR

fs, you're angry because I understood the OP's comment that you missed?

Loony Tune characters? Tell me which other LT character name(s) you think I've used.