This includes all new plumbing, furnace, hot water heater, and new radiators or baseboard.  

If a boiler, you should expect to replace the likely cracked boiler and radiators. 

As @Ronan M indicated they are common for years in other parts of world (I see many in Europe where the heating is often primary radiators (no ducting) with Splits providing supplemental heat and AC. 

She bought a dosimeter and started checking radiation levels around her house and at her kid's school.

I don’t use them for my properties for the same reason you’ve encountered “no central heating” (I have radiant heat but no radiator in my bedroom).

When he returned, the furnace had sent water through pipes to third floor radiator which flooded third, second and first floors.Plumbers insurance company and adjusters are offering $1,500 where we think repairs will run approx. $7,000.

., 2 bedrooms and a bathroom floor around 1 inch; may need 3-4 more footings and floor joists (max $3000) ....2)roof shingles replacement (~$7000).... 3) kitchen complete Reno, countertops, cabinets, appliances, flooring (~$30,000 )..... 4) on 2nd floor, add master suite by converting one existing bedroom and common area ($40,000).... 5)galvanized plumbing ($5000)..... 6) old electrical ($5000).......7) restore a garage that was converted to closet+laundry room around 50yrs ago (~$3000 max)...... 8) remove radiators and the heating unit.....

Sometimes it freezes in the winter in KCK [citation needed], so you also get to install some kind of heater in the garage - whether that is electric, or gas, or even a radiator coming off of the water heater. 

I actually don't think it's steam but it does use radiators.

If you don't have ducts installed, or have electric heated water-filled radiators, converting that over to gas for heat is going to be very expensive.