I wouldn't want to use those oil heaters, theres no fan force behind them so you will just end up with a bunch of thermal layers.
That other unit linked drawing 1200W seems ok its still a fair bit of draw.
I would be looking for a decent heat pump, I dont know why people keep suggesting other sources of heat, A heat pump will beat most other sources in terms of efficiency and upfront cost (similar sized units ) + its fan forced so you will get a better result vs heat just being dropped in one area then raising right to the ceiling. This is all quite a waste though without adequate insulation imo. I am not saying other methods wont work I just dont really see the point looking into them when they all pretty much use more power and put out less heat the only positive I see is some of the small units have a much lower price tag. This method is also pretty simple once its installed just turn it on set the temp you want and when that temp is reached the unit will cycle off and on when required.
That other unit linked drawing 1200W seems ok its still a fair bit of draw.
I would be looking for a decent heat pump, I dont know why people keep suggesting other sources of heat, A heat pump will beat most other sources in terms of efficiency and upfront cost (similar sized units ) + its fan forced so you will get a better result vs heat just being dropped in one area then raising right to the ceiling. This is all quite a waste though without adequate insulation imo. I am not saying other methods wont work I just dont really see the point looking into them when they all pretty much use more power and put out less heat the only positive I see is some of the small units have a much lower price tag. This method is also pretty simple once its installed just turn it on set the temp you want and when that temp is reached the unit will cycle off and on when required.
