Ceiling and walls radiant heating system from 1968

[Steve Graves]

Bought a rehab in a mountain area and when I purchased it we didn't think it had a heating system, only the fireplace. Yesterday, the old owner stopped by to look at the place and talked to my contractor. He informed them that the house does have a heating system. It has wall and ceiling radiant heat. I've never heard of this before. I knew about radiant floors but had no idea this style of heating existed. 

Does anyone on here have and use this type of heating? We now know what the blank switch panels were used for that are above the regular light switches. I'm trying to find out who I can call to have the system checked out to make sure it's still safe. Also, with the cost of electricity now is it even worth trying to get the system up and running?

Any help and info is greatly appreciated.