You mentioned radiators.

(rented out at $700/mo. each)2200 sq. ft. totalbuilt c. 1932hot water (radiators)aluminum sidingdetached 2 car garageZillow estimates value at $139,000 (but also has the incorrect age of home - about 40 years newer than it is)Rehab needs - I based many of the cost estimates below very conservatively (new to business, no experience - wanted to build in cushion) based on local prices I got from professionals, but I may be significantly over on some estimates; although I may do much of the rehab myself, I based estimates on paying someone else to do it.- new kitchen (countertops, cabinets, sink, DW) in one unit $5000- asphalt shingle roof about 20 yrs. old $6000- exterior paint (garage, rear porch) $1000- refinish hardwood floor (one unit) $1500- interior paint $1000- one unit's boiler (looks original!)

The home had a boiler, all of the piping (asbestos) leading to the radiators was wrapped or jacketed in a protective jacket, ( to keep the asbestos from becoming disturbed and air born.) 

For the drain lines, the traps are where water is held, so as others have posted those are filled with RV antifreeze; don't use regular automotive radiator antifreeze.  

Most of the apartments down there are not in good locations though.I like areas like Scottsdale, the general area of the Esplanade, and up around the 7th street/Missouri intersection (radiating out for a mile or two). 

However there's only 1 water heater and 1 furnace to heat the water and radiators (its an older rental).

Two sets of radiators stolen, and an underground drain that needed to be dug up later.

The radiators that were there have all been removed, and the furnace was removed at some point too.

The system is a boiler and all the radiators are missing. 

Radiators.