Heating......again

[claypot]

Looking back through the forum this topic keeps cropping up at around this time of year, and yet again my problems have started.
To-date I have relied on electric heaters in both my greenhouses with propane backup for the intermediate greenhouse and paraffin for the cool greenhouse. Paraffin is not economic these days and is not automatic (it just burns without thermostatic control) and requires constant attention to top up.
My problem is that my latest home is very rural, served by overhead electricity which is unreliable. We have no gas and home heating is oil. Quite apart from alarms etc to know when heat fails to put on backup (if I am around) the supply breaks and surges severely and I believe is damaging my equipment. We cannot, for instance, have digital timeclocks on heating - they just go berserk. Electric heaters have served me well in the past but even they are failing now - either fans or elements.
As I have propane installed for one greenhouse as backup, I am considering switching to propane as my base heating system for both greenhouses because that works reliably without any electricity and keeps very stable temperatures. Automatic changeover of tanks runs smoothly and I have a replenishment source nearby.
Propane runs a Shilton unvented heater with appropriate ventilation for clean burning. Admittedly propane is costly compared with electricity, but I have to consider it against loss of my collections through heater failure. Reliability is the key factor here.
I have never used my unvented propane for long periods so wonder whether there is anyone out there who has such experience. I have never observed detrimental effects on my plants with either unvented Paraffin or Propane.