What the XXXX is a BTU when it’s at home?

Since I last made a contribution to this column I have been looking in to options available to providing an alternative to my current Kerosene fuelled central heating system. To be honest, given the convenience oil or gas fired central heating has over others, it is hard to identify a system that uses a fuel that will give a corresponding convenience. Flick a switch and it’s on, and there ye are feet up drinking yer coco watching Emmerdale. I went to see a chap that sells wood pellet stoves and he spoke in glowing terms (excuse the pun) about the merits of his stove - “110,000 BTU output", he said as he patted the stove in the manner you would reward an obedient collie dog.