Hot air duct insulation Thermo Top, Eberspacher, Wallas boat heaters

Puzzled long and hard on the best way to complete this job. The diesel heater outputs around 2Kw, the hot air ducts around 2M in length so a lot of heat is wasted in the ducting, warming the area under the seating so it seems sensible to try and attenuate this.

Out wwith the trusty Singer
The ducting run
Installed! I fixed something!