ASHP are claimed being healthier than fossil-fuelled heating like fuel heaters by preserving a more even temperature and avoiding destructive fumes hazard. Split Units: Have a person coil and lover inside of and just one outside the house. Source and return ducts connect to the indoor central coil and fan. https://purethermal.co.uk/media-news/q4-launch-lithium-large-capacity-r290-ashp-from-pure-thermal-and-enerblue/