Do not start there, It is a ton of work, concrete can be damaged by heat and there is no guarantee the foundation was sound before the fire. 

First one was trim nails driven into baseboard heating pipes that sprung a leak and flooded two rooms, next was a leaking main water valve in the boiler room that flooded the same unit... 

The water heater is required in most jurisdictions just like a source of heat.

Best is oxidation ie UVC, o3, H2o2,  dry heat over 125 deg and plant based  surfactant cleaner all speeds up the process and is safe non toxic.mold test maine runs $75-100 sampled by generalist sent to  certified 3rd party microbiologist with quantitative test results over qualitative preferred. 30 or less CFU is expected range.if need court expert or Osha complaint  hire an industrial hygienist $450-600 per report. .i charge $85 ea.

We got hit with a $1700 bill to heat treat bedbugs after purchasing a new property.

It also came with a new Buderus, 4 zone heating system and central air.

I've been in the house for a little over the year now, but I find myself REALLY missing living downtown for quite a few reasons (convenience, saved time, yardwork, etc etc), so I'm trying to see if it can make financial sense at all for me to make it happen or if I just need to suck it up and stick where I am for a while.I ran some numbers, and here's where I landed (Please let me know if I'm missing something):House Expenses:Mortgage/Interest/PMI/Insurance/Taxes = $1,370/moMaintenance (Assuming 1% per year) = $181/moIf I were to rent it out, presumably the tenants would pay the utilities, which come to an average of about $187/mo (heat, water, electric)I expect I could get $1,600-1,700/mo in rent.Obviously if we were talking about a pure rental investment, the numbers don't really add up, but since I already own it, I'm trying to determine if it makes sense so that I can move pack to the place I want to live. 

My plumbing and heating guys are starting next week and I’m +90 yards of dumpsters into the renovation, so should be a good time.  

You made me scrutinize myself a bit more and I realized there is no indication of multiple heating units or meters and I will need to dive a bit deeper into this. 

Dumpster rental, electrical bills to keep the heat on during winter so pipes don’t freeze, man labour.