The award winning High Efficient Fröling P4 Automatic Pellet Boiler. One of the world’s most sophisticated pellet boilers with Lambda control. Fröling P4 boilers provide a convenient, safe and environmentally responsible way to heat space and hot water with wood pellets. P4 owners are assured of unusually high heating efficiency, low heating costs, and use of an abundant, locally available, renewable fuel. With its ingenious, fully automated operation, this boiler is amazingly easy to use.