I have just bought a ranch home built in 1954 with radiant ceiling heat. The original owner/builder (deceased) also owned the local lumbar yard. It seems rock solid, with cedar wood and beautiful masonry. Lots of attention to detail that tells me things were done right the first time. I have questions about the radiant ceiling heat of that era. I have been told it is wires/coils sandwiched between 2 layers of sheetrock. The ceilings have a textured finish==sort of like flock or popcorn. Do I have to use a special product to repair cracks in this because of the heat coils, or can I use regular plaster repair stuff? Are these systems 110 or 220? How efficient are they and can I do energy efficient upgrades without replacing the whole thing? Any and all info will be appreciated. Thanks!!