Is it possible/allowed to mount this boiler 20cm higher?

I’d like to put a tumble dryer on top of the washing machine here, but the boiler is currently in the way. If it could be moved up, around 20cm higher, it would work…

PS one issue is that the flue has only 15cm clearance to the ceiling but I’m wondering if there could be a workaround, like a shorter flue or recessing it into the ceiling.

Any thoughts much appreciated!!