The only real reason to replace it is if you needed to demo it to get to electrical/plumbing behind it, or if there is a mold issue or ongoing water issue.

I buy property from the 1880-1920 all the time and don't have to deal with anything other than brining them up to modern code...but in my locale, that's only required if you start doing work...ie if I don't touch the electrical I don't have to worry about upgrading it, but as soon as I touch it...BAM!

There were issues with termites, the electric was really not up to code, the HVAC was complete trash, there was mold, and the inspector had doubts about the health of the roof because he couldn't get into the attic to inspect it because it had been sealed off apparently for who knows what reason.

He does plumbing, electrical and carpentry.

Also in my county if it has been vacant for more than a year power is disconnected at the main, in order to get it turned back on electrical must be updated.

LVT Plank for floors etc in the future (also recessed lights)Basement: Cleaned out, updated electrical, plumbing, and GAS (used to be oil) with new central HVAC unit installed and ready for hookup to the PGW line (waiting on PGW). 

You'd have to be able to convince tenants that the higher rent you're charging (compared to the local competition) is worth it because the tenants will save money on their electricity bill each month.

Have the roof, water lines, underground sewer lines, electrical and heating and AC units checked.

Install it first thing before/right after closing- pro- instant protection for everything to comecons- when they do electric, it'll be going on and off, the base will get moved around, I think it'll just trigger a ton of false alarms/will be non-functional half of the time. also will have to take sensors down for drywall and paint2.

Okay, numbers:Purchase Price: $47,200 cash (County Foreclosure Auction)Renovations/Holding Costs: $33,792 cashSale Price: $129,900Closing Costs: $14,378Total Profit: $34,630Renovations (Contracted):New RoofNew Windows2 New Electric Subpanels for A/CRenovations (DIY):Gutted the kitchen, opened up wall into Bedroom #1Relocated front doorFramed out closet in what was the living room to make it Master BedroomAdded a half bath to the laundry room area which became master en-suite (the home was permitted as a 1.5 bathrooms and when we got there there was only 1 bathroom so we added the half bath)Redid the kitchen entirelyCompletely redid the bathrooms, turning one into a 4-pieceNew floors throughout houseNew landscapingI estimated about $30k in repairs (after initial walk-through and having already purchased the property).