In brief, I have a rented condo that was damaged due to an upstairs unit leaving their bathroom water on.

(see below)Above tenants have destroyed our bathrooms due to constant nasty toilet water damages.. and constant noise violations have caused my family to suffer from sleep deprivation.

Hello BiggerPockets, I went to an open house for a property that was listed as a 2 family but with only 1 electric meter, 1 forced-air gas furnace w/central air and 1 hot water heater.

Total cost of materials was around 70k, labor was sweat equity plus about 30 K in other labor cost (sewer later pull, back-flow valve, tankless water heater,4  mini-split units, sub-panel etc).  

@Ryan Kelly mainly north austin close to Apple campus and new water park in round rock

For homes for water heaters 4 Plex for water heaters I think you get the picture.

They claim even after running multiple rinse cycle, the water is running brown.

My water/sewer usually runs about 225 for our lower unit of a duplex.

There could be involuntary liens such as code violations, water and other utilities that survive foreclosure  and are not necessarily recorded 

If the equipment is older than 10 years, I would say stop wasting money on repairs and get it replaced (you may be able to reuse the existing outside compressor it uses R410a refrigerant, but if its R22, it junk).The way they left it, it is not operational for either heat or cooling.Personally, I would review what you paid to the original HVAC company and see how they took advantage of you.