As an electrical engineer I did a lot of research before installing a Lowergy 9KW heat pump in our 3 bedroomed bungalow and I am more than happy with the results. We still have to use our oil fired system for hot water and to supplement the heating on the coldest days. Now that we use a heat pump for our main heating requirements, our oil consumption is greatly reduced. I have fitted a Smart Meter to record our electricity usage at the tariff that we pay and it shows a cost of only 8p - 14p per kWh (16p per kWh unit) for the running of the heat pump. From my experience, a saving of up to 50% can be achieved on heating bills by using an air to air heat pump instead of oil or gas.