Not suitable for just anyone but I get excellent results with my food dryer. Maybe an oven on 50°C would be suited as well, but I let them sit in the food dryer overnight, ten hours or so. Might be a tad long for running an oven.
I had the idea because of the hint of letting them dry on the heater overnight though, only in winter, of course. In the end, it seems to be the mix of temperature and time. In the right ratio, temperature can shorten time, but in the long run, it still might give even better results to leave the hair culed after heat application as long as can be afforded. As curls always seem to tend to loosening in the long run. I once read someone let the curlers sit over a whole month! I find it difficult to get the right point where they don't move anymore at all. Also, some hair colors take curls more easily than others.