The Geysir Wood 5S is capable of burning wood, pellets, and multi-fuel without any problems, or operating in a combined mode. Once the boiler is prepared for ignition by inserting wood into the combustion chamber and pellets or multi-fuel into the tank, the ignition plug and its relative blower ignite the pellets, which in turn trigger the ignition of the wood. When the wood reaches a suitable level of combustion, the electronic control stops the supply of pellets and the boiler operates exclusively on wood. Upon exhaustion, the boiler automatically restarts with pellets or multi-fuel. If the system no longer requires energy, the Geysir enters stand-by mode, reducing wood combustion to a minimum by automatically closing the combustion air intake. If the boiler is working exclusively on pellets, wood can be loaded normally through the door. Upon opening the door, an actuator opens the smoke bypass damper, directing it straight into the chimney while increasing the extractor's power. This prevents the abnormal escape of smoke into the technical room, a principle that applies equally during pellet or multi-fuel operation.