how small the vents?

[doctormark]

I am restoring a historical mansion in Pittsburgh and want to get rid of the antique furnace/radiator system. It's a 2.5 story, 6500 sf brick home with uninsulated plastered brick walls.

I'm figuring on putting in two 2BR 1BA apartments and one efficiency upstairs. I'm thinking about putting in some combination of heat pumps, electrical furnaces, and baseboard units. There are 12 foot ceilings and I've had one suggestion to lower the ceilings (using drywall) maybe a foot or so -- just enough to provide room for vents throughout.

I'd like to avoid lowering the ceilings. I am wondering if it would be possible to maybe make the vents small enough to disguise them as cornices. If I could get away with vents that were 8" square to 10" square I could add some decorative molding and have "invisible" vents. Maybe a higher capacity fan than usual could push enough heat/cool through to make it work?


Each of the 2BR apartments are going to be about 1200 sq. ft. and the efficiency about 500 to 600. Each of the tenants are going to be responsible for their own electrical so I'm thinking maybe a separate heat pump for each of the 2BR's with an electrical furnace built in and baseboard heat for the efficiency.

Maybe a larger capacity heat pump for the 3,000 sf downstairs and common areas.

Any thoughts?

Many thanks.

md

[air of honesty]

You mention that you have already had suggestions, presumably from someone local who has seen the structure. If not, then you need to get several. The kind of project you are undertaking requires experience and knowledge. Find a contractor who has worked on similar structures with results that like and then believe him when he tells you you need to furr down in certain areas for the mechanical realities of creating separate households out of one building.

There's nothing worse to me than watching a place made architecturally beautiful and unlivable in the same stroke.

[brian in mass]

Sounds like a job for Unico !


i do homes like that all the time and Unico might be the answer your looking for.

http://www.unicosystem.com

[doctormark]

Good point. The purpose of the place is for human beings to live in it.

And good suggestion about finding someone who has done this kind of work before.

The word I wanted to use was not "vent" but "duct". I gather that the maximum you want the supply air to move is 700 fpm. Is there an established minimum cross sectional area for ducting?

md