The fan attached to its ply mounting

The truck has a woodburner in the living room, but I was worried that while it might be tropical down there, the other end of the wagon might be baltic. The solution is what has become known as the WaftOMatic, which does what it says and wafts warm air from one end to the other.
A computer fan, some 4″ drain pipe, lagged with foil insulation, pulls hot air near the ceiling behind the woodburner flue, passes through the shower room, where it takes the edge off the chill, and then wafts the warm air out into the kitchen/bedroom. The only fan I could lay my hands on turns out to be lit by LED’s so the intake emits an eerie glow which at least reminds you it is turned on.
At some point I’m determined to make a little circuit with a thermistor in it that will switch the fan on when the air temperature reaches a certain temperature, but that is for another day.

The duct passes through the bathroom