I think I understand now and you are saying that you have heat but the thermostat is downstairs so upstairs would have no control over the temperature .... is this correct?

They are typically at least $300-500 though.There's also some models of window air conditioners that work in reverse cycle but every one I've seen is at least $400.A 2 ton ductless system is $950 on eBay and will probably work better in heat pump mode at low temperatures.

I'm trying to find out what the "TEMPERature" is like out there right now....

Joshua, Attic fans are simply a fan with a thermostat that cycles it on when the attic temperature reaches a specified temperature.

There is a minimum temperature the heat must be kept at although I’m not 100% sure what it is in NYC.

However, the temperature is a good 5 or more degrees cooler with less direct sunlight than upstairs. 

If there is no existing ductwork, I might lean towards a ductless heat pump since they are pretty efficient at low temperatures.  

I would suggest to make them put the utilities under their own name (if possible), because even if you put it as included in the rent, unless you charge a good amount, they will abuse it (turn the heater that extra temperature, take those extra 5 minutes in the shower, etc.).

It's leveling off, but that's like saying the patient's temperature is 107 degrees,'' said bankruptcy court Clerk Jesse Clark.

There is a pressure relief value on the HTH that will release if the pressure or temperature gets too high.I've heard of investors preemptive removal of furnaces and roof before, but we've never done that either.