Evan Davis & Bean Beanland talk about anything and everything to do with Heat Pumps. It's a UK objective to replace gas boilers over the coming two decades, with heat pumps being seen as the obvious alternative. It will be a massive project to change the way we heat our homes - we might be installing 25 million of these devices in the next three decades. So what are they? What do they cost? What are the positives and negatives of heat pumps? Always curious about the scale of the transition upon which we are set to embark, Evan will be looking at...