Central Air Conditioning in Old Buildings

The vents in the LR and DR (visible in the pictures of those rooms) suggest that there is ductwork running through the northwest wing of the apartment. The ceiling of the corridor in that wing has probably been dropped for ducts and mechanicals. It's hard to tell where the exterior mechanicals have been mounted. The kitchen wing seems likely. The owners bought the "B" unit in 2007, so the system is nearly new, and should be relatively unintrusive.

Good luck..I think every building is different. We're renovating and ultimately were turned down by our board even for the quietest units we could find. Our architect showed the board president three different models installed and running but with our building (also same time frame built) they didn't go for it. A couple decades ago two other spaces did get board approval but, when they went to re-renovate about five years ago they were denied anything further. Frustrating, but at least we did get permission from board and landmarks for a few more through the wall units. Good luck...Leslie

So if we buy an old coop - if the building allows us to put in central air and there is no terrace and the ceilings are high enough, is this doable? Does this mean no radiators, no window units and no hvacs (all of which I hate and wouldn't buy if we couldn't put in central air)

The compressor can go under a window, like a big through-wall unit. From there you run the refrigerant lines to the air-handling unit.

The air-handling unit needs access to a drain line, as the condensed humidity has to go somewhere, so that limits where it can go. It can be ceiling-mounted, where those're high enough.

As West81st said, it looks as if the compressor's under a courtyard window, with the lines running to the handy NW-corner space, with its plumbing and scope for ductwork. There could be other lines running to an air-handler on the south side of the apartment.

So does this mean that as long as the building allows it and the ceilings are high enough I can look at any building and add central air? What do you do with the radiators and what is the downside of converting an apartment to central air vs. buying a new building (other than the hassle)? Does the sytem work as well? Do I hear the pipes clanking as is often the case in radiator buildings? How much clearance do I need in the ceiling and would I only have to lower the ceiling in certain rooms?

I wouldn't say any building.

For heat, most people with through-wall or central AC keep radiators under the windows. You're paying for the building's steam, so no sense not using it. Some buildings specify that new through-wall or central systems have supplemental heating capability.

9' or higher will give room for ductwork. There're almost always hallways, closets, etc. to run ductwork without lowering main-room ceilings.

If it's a big deal to you, it'd be worth getting an HVAC consultant to look at any apartments you're thinking about.

I need to post pictures of my AC system. Someone asked earlier. We have a mini-split system mounted internally. Air intake comes from a thru-wall vent below a window. Hot air exhaust goes out the window through a louver. The louver required landmarks approval as we were replacing a window w/ the louver. The main difference between a mini split system and a trad'l central AC system is the lack of ductwork. I have 8 foot ceilings in my prewar, but crazy beams dropping height in placed to 7' 3". Instead of ducts, small refrigerant lines are run to each of the four air handlers. We've got 4 zones: MBR, kids' rooms, LR and kitchen. In addition to refrigerant supply/return lines, there is a condensate drain line and a control wire for each air handler. The bundle is something like 4" in diameter -- much smaller than any ducted system. The unit is whisper quiet. The condenser is actually in a dedicated mechanical closet off my son's room. Even w/ all 4 zones running, you cannot hear this thing in his room.

It took a while to get board approval on it, but once Landmarks was OK, they were OK.

This video shows something that might be similar to earo's setup:
http://youtu.be/WFSjT5Hi-r4

Please note:
1. I merely found this in a web search. I'm not recommending this company, and I don't know if they did everything right
2. I'm not so sure this box-in-the-window solution allows the exterior to work the way it's supposed to. They're usually exposed to exterior air on all sides.
3. The conduit used here is ugly (but no more than the contents of the apartment) ... in most cases it could have been boxed into wall extensions
4. I hate the look of the inside units of these systems. But millions of users worldwide don't care.
5. I think the heaters in these are very inefficient for our climate, so I'd leave the radiators in place and just get used to them

That's probably a C-line at http://streeteasy.com/nyc/building/40-west-67-street-new_york

They wanted to keep the big leaded-glass window in the LR, which doesn't have much room underneath for through-wall, so figured they could live with the mess they got.