Over time, the subfloor secured by the old nails starts to loosen through natural conditions (humidity, change in temperature).

At least there is a GFCI circuit breaker at the panel.During the summer the double pole thermostat is then flipped to the max temperature to trigger the feed but the wall heater is turned off at the heater so the feed is now only live to the a/c unit.Access to do a separate feed to the a/c is not possible without tearing out walls.It's an interesting concept do you have any Suggestions???

@Josh PrihodaI would turn on the electricity, and make sure everything works while maintaining the correct temperature and humidity in the unit.

You will always have a 7-10 degree temperature change from 1st floor to 2nd floor, purely because hot air rises and cold air falls.

But it can easily still be a workmanship issue (probably is).If the issues are at the outer wall, it could be a scupper drain hole, the seams or laps where they heat welded the laps, or even the metal coping on top of that wall section there. 

I would say most third party sites are good for getting a temperature reading of what's going on with your credit and for monitoring any new established credit in case you've ever dealt with fraud.

We probably get 15 days a year of freezing temperatures.

What is the temperature in the apartment when it's "fully" heated?

@Conte Cuttino If you turn the tank temperature up and have your plumber add a mixing valve you affectively can turn a 40g tank to a 50-55

I used to do a good bit of work but went back to a 9-5 welding.