If the housing authority stopped paying then it could be because for many reasons but my best guess would be it failed the annual inspection and work is needed. 

You say cast iron- rip all that out and replace NOT reline it will fail in 9 monthsMarketing and waiting carry costsContractor profit 10%Or are you handy enough to order everything and replace the electrical panel?

We leave a quarter width gap in the back so that if the wax ring ever fails we know immediately from water seeping around the back of the base instead of through the ceiling below.It's rare, but sometimes we get called back for a sewer odor.

There are lockable thermostats for commercial use, but I can't see that working in a rental.I think the main issue will always be that any thermostat that you can set a minimum temperature in will always be susceptible to this fail safe failing, due to the possibility the tenant could change it on purpose or on accident.I'd hope in a 4 plex as long as there is no building defect to the thermal envelope that it would be difficult for one units pipes to freeze as long as the other units were occupied, seeing as they share some common walls/ceilings.

Is it possible to succeed, of course, but most fail because they really don't know what they are doing.In the past, got deals prior to MLS which allowed me the best opportunity to wholesaler today, that is no longer possible unless you direct mail advertise to motivated home sellers.

Investors fail to properly include long term expenses, never consider amount of equity sitting dead, never account for the truly unexpected etc.

This is the main reason why a project would fail and that’s probably what it is when you see idle building frames in the landscape.There’s another version of that same risk when the developer uses the money from his first buyers for anything other than the construction like personal expenses for example.

All of us have to fail to learn.    

I have owned a failing park in Kanas.

It's no surprise there is a close to 90% annual fail rate in the industry.