Ah OK, I'll have to look into it then. It's been operating like this from the first cycle.The whole design of a heatpump dryer means it recirculates the air inside that's where the efficiency comes from it just needs to keep the air warm and it then reduces the moisture from that air.
They're basically a dehumidifier in an enclosed space.
It's a Candy GVSH9A2DCE if that helps anyone with deciding what to steer clear of.