Well, open fire places are not really worth it to invest money in. They're a permanent drain of energy and money. A so called water pocket stove (Holzofen mit Wassertasche, OBI oder Hagenau, check the home pages/catataloges)is much more efficient.
These come in various sizes and outputs. Check the output ratio of these. Some deliver 20% of the thermal energy by radiation straight into the room they're placed in and 80% into the water circulation.
Pressurise your heating/water system, throw out the tanks in the attic, insulate it.
If you own the LPG tank and you're not hooked to the dealer by renting it then you can shop around on the free market for the cheapest LPG.Check the yellow/golden pages for suppliers.
The free market LPG costs about half the money as if purchased from the tank owning company. About the same as oil or natural gas when looking at the price per kWh.
For heating questions this forum in German language might be a better choice
http://www.haustechnikdialog.de/ How to get out of tank renting contracts check the homepage of the " Bund der Energieverbraucher ".
In principle call the tank owner, tell them you're thinking of switching to oil or whatever if he doesn't sell you the tank. Usually a sucess if the tank isn't to new.
Check the www. for tank manufacturers and ask them what they charge for selling and installation/comissioning. You would be surprised how cheap it is.
I bought mine for € 800.- some years ago. VAT and delivery,comissioning/connection came all together to ca. € 1,000 .
Now I pay 35-40 Eurocents per liter, depending on the oil market. Before it was at least twice this price, plus the anual rental fee of about €90.-.
Within 2-3 years the initial investment was earned back.
Good luck!
