I've just purchased a 50s era house in northwest Ohio, where it has been about 20 degrees for the last month. The gas service has been turned off and the interior has been holding steady at 30 degrees.
When I get the heat back on, how gradually should I reheat the house to minimalize plaster ceiling or wall damage?
The walls and ceiling are not the main issue. What about the pipes, traps and plumbing fixtures? Were they treated for freezing before the heat was turned off?
I would make sure the water to the house was shut off before you start raising the temperature.