Thanks for getting back to me, my problem with the heating is that I have 8 separate self-catering apartments of various sizes which I rent out over the winter and summer periods. In winter the temperature rages on average from 0 to -15 and can occasionally go down as far as -25. I cannot control the heating as the apartments are rented out to holiday makers who will not care about the settings as long as they are comfortable.
In the main the heating works quite well and maybe only when the temperature really drops does it feel like a bit more heat would be good. However when the outside temperature is not that cold outside it can be a bit warm and of course the guests will open the windows and let the heat out.
The heating is controlled by thermostats in each of the apartments and these cannot be changed by the renter, the output dial is hidden behind a plastic blanking cap, so this controls the output effectively. I cannot see how the input is regulated and I am assuming this may be manually set and cannot be adjusted. I cannot think it would be automatic due to the age of the heaters.
To install a water based heating system would be a massive job as all the floors and ceilings are concrete and the apartment house is on 4 floors. Not only would it involve a large amount of disruption but the cost would be very high.
My object therefore is to try and minimize the installation costs by sticking with electric heating and buying in new storage heaters if they really are more efficient. I have had a suggestion from a local heating company in Austria, that electric oil fired heaters would be less to run as they are easier to control, I am not sure about this as I would then be running on daytime electric. The storage heating system in Austria is similar to the economy 7 over here in that it is much cheaper at night.
I have been thinking of maybe just changing my large apartment as I get a separate electricity bill for this as it used to be the owners apartment, whereas the rest of the building is treated as business, both bills are using the same tariff. I can then see if due to the upgrade I am making a saving on the monthly bill. However this is still a costly exercise as I have to change 8 storage heaters and they are all over 3 kw, and I am not sure if I would be doing it for nothing or maybe only for a very small saving.
Last week a friend suggested looking into warm air heating, but I have yet to do this.
John