The plan is to put in a Nest, or similar, thermostat in the whole way (under a lock and key) so to be able to control the temperature from wherever. 

If the building is large oversized freestanding radiators I'd highly consider swapping it out for a couple of wall mount boilers that are daisy chained together with outdoor temperature reset control. 2x reasons, it can modulate the temperature of heating water on mild days and if the demand is low it only needs to use 1 boiler.

What was the temperature when they called? 

It will make the temperature in the shed much hotter.

To help best monitor an appropriate temperature for the apartments I think it would be helpful to have temperature sensors in each unit.

@Mike Cumbie you are a realtor, so tell me how do you spin those -100 degree temperatures and the fact that no plant life can exist? 

It helps to have controlled temperatures, ventilation and to find any seepage of water from the outside.

You're going to get some heat coming off the flue pipes from the boilers first of all so you may not have enough clearance to keep from exceeding the temperature rating of the wire and PVC. 

How do you take the Real Estate markets temperature everyday so to speak....?

It’s mid september in NYC, the temperature is between 65 and 80 degrees.