Question: Could you please address the fuel consumption of forced-air bus heaters vs. the Refleks?
Answer: An accurate comparison of fuel consumption and relative efficiency between the two technologies would require equipment and time we don’t really have at our disposal. However, since both systems burn with an essentially clear exhaust, indicating good efficiency, and diesel fuel has a fixed amount of available heat per unit of volume, I think we can assume that their base efficiency is very close to identical. But the air bus heaters lose a lot of heat through their ducting, as much as 20% in a cold bilge, I’m told, and in addition, more fuel must be burnt—unless the boat is fitted with a wind generator and the breeze is very steady—to replace the electricity used by the bus heaters. Bottom line, I would expect the Refleks to be a clear winner in overall efficiency.
See this post for a general comparison of the Refleks and Eberspacher heaters.