I have a Wallas 3000DX (10,000 Btu) on my C-42. I am very pleased with the heater, its electrical demand is much less than the Espar or Webasto and it seems to be equivalent in
fuel consumption. 2 gallons of diesel will last about 3 days of continuous use. The heater is also very quiet. We liveaboard in SF bay so we rarely get frost or below freezing temperatures.
Rod, S/V Sashay