I’m buying a home in Brooklyn soon (you may remember a recent post about insulating south-facing windows in a landmark building). I’m now looking for HVAC providers to install a ductless mini split system, and before I proceed, I’m researching how to ventilate a house with these characteristics:

* It is three floors plus a basement
* It is attached on both sides
* There are currently no ceiling fans in the house.
* The front facade cannot be visibly modified, on account of its landmark status. 
* The basement is cooled by a ducted a/c system, but no other portion of the house has any mechanical HVAC systems; it is heated by a boiler and radiators. The basement’s system is 15 years old and doesn’t heat, so I’m considering replacing it with a newer system that does heat, especially if there are efficiencies to be had by pairing it with the rest of the house’s mini split(s). (I know HVAC should be kept separate from ventilation systems; I’m just providing this info in case it’s useful.)
* The 3rd floor bathroom and the powder room next to the kitchen both lack exhaust fans. (The bathroom has a vented skylight, which I’m not keen on from an energy perspective, but it is beautiful…)

I’ve read a bit about ductless ERV systems like the Lunos and the Blauberg. Would these work in a house whose front and two sides are not available for the installation? (I’ve attached a floor plan. The rear of the house is the north side. Note that the kitchen, which I presume is the most important room in the house to ventilate, is also the only one with a north and side wall. Is that a good application for a ductless ERV?)

Then there’s standalone ducted ERVs like Panasonic’s WhisperComfort. Can this type of product replace a bathroom exhaust fan? Or would the heat recovery process leave all the humidity in the room during showers?

And at the risk of being too broad: Are there any risks or opportunities I’m not considering?

I’m in zone 6B.