Stan's antique Mosler sounds virtually identical to the very large commercial safe my friend has in his garage. We about killed ourselves just getting it unloaded and into his garage when he bought it and brought it home on a tilt bed car hauler. Getting it into his house without major modifications would have been impossible. But even with temperature and humidity extremes from dry sub-zero in winter to extremely humid 100+ degrees in summer, his Goldenrod and normal maintenance keeps his guns, micrometers, verniers, and other tools rust free. Just that low wattage gentle heat source is plenty to keep the inside just slightly warmer than the outside so that any damp air cannot condense on the surface of steel.
