In last month’s issue, in an article entitled “HEATING COSTS EXPLAINED”, I looked at the different costs of heating using different energy sources. I stated that heating from a heat pump was one of the cheapest methods of heating. I stated that the heat would need to be stored in underfloor heating or buffer tanks. It has been pointed out that I omitted any information about sizing of buffer tanks.

A 1,000 litre tank will absorb 1.16 kw for every degree rise in temperature. The total storage capacity of water if we assume a 10 C rise in temperature is 11.6 KW per 1,000 lts (1 tonne).If we need to store the output from a 100 KW boiler for 1 hour we would need  10,000 lts (10 tonnes) of water.

I therefore conclude that storage of any significant amount of heat energy in buffer tanks is not practical.