I've installed a couple of Econo Heaters in 2 of our bedrooms.
I have to say that at best they only take the edge of the cold air. I bought the largest radiators on offer and according to the instructions they should be adequate for the size of the rooms? When we first installed them, I left them on all day to test them out but the room temperature only increased by just 1o
Perhaps if you installed two of them in one room they may perform better?
The best heater weve bought this year is a Campingaz Calor Gas fire. It heats our lounge very quickly and and the Calor Gas Container costs only 11 euros to refill. It lasts on average a couple of weeks which is superb value in comparison to oil filled electric heaters or using our Air Conditioning system.