How long to charge up a late 80s forced air heating system?

I am wondering if it has been switched off completely for many days and lost all heat, how long it would take to warm back up a forced air (warm air) heating system to a reasonable level, before I could use it again? I had it on last night on 'night charge' and its tank feels no different in temperature today. It has taken literally nothing up in electricity for this. It is seemingly switched on - its 'night charge' dial can be changed, with what I think is a power level of 1 to 6, but for how long it charges overnight on its 24hr clock dial cannot be. Its an electric only system, and was installed previous to 1989, which is seemingly the year when it was first ever checked for any faults (there is a label on the front of its tank with the dates of every check-up). I am in the uk. These systems are quite popular up in the highland area compared to everywhere else. Thanks for any information.

Well obviously not heating!

There may be an overheat stat which needs manually resetting.

You will probably need to call a pro.

Tony

I might re-check those controls and give it one more night, but if nothing works then ill definately call. I do wonder how long would be normal to completely reheat such a system back up if it was working 100% - do you think one night of charging shouldve been enough? I guess I need to find someone with a system of the same age to compare, but perhaps its finally given in! thanks