Autoterm 4kw heater was blowing smoke out into the cabins

[Bodach na mara]

When that happened with my Eberspacher D3 it set off the CO sensor in the aft cabin, which was filled with smoke. The Eber had been unreliable and was prone to flaming out. The collected wisdom of neighbouring boat owners was that the wind on the stern had forced a flame-out and then blown all the resulting smoke back through the combustion chamber and into the hot air feed to the cabins.

Certainly, I have had no trouble with the Planar (now called Autoterm) replacement even though most of the original exhaust was reused. But I am now careful to avoid using the heater if the wind is on the stern.

 

[mjcp]

on another note. is there better ducting available without the need to insulate it as the aluminium duct gets bent and torn very easily in the locker. i have only ever been able to heat the stern cabin and galley never had enough heat to heat the forward cabin on my small 30ft boat which i suspect is due to heat loss in the ducts

On my 33 foot boat with real 'basto, the ducts to the forward end of things ran between the hull and a water tank, both excellent heat sinks! I insulated the ducting with a foam lagging rated -60 to 110 C. Its the stuff you see on refrigeration pipes etc. access was a bit limited, so needed to slit it, wrap around and cable tie / duct tape in sections rather than slip on in one go. Other than that, straightforward and decent heat up front now, so much so that controllable vents were requested: the little fore peak not needing as much heat as the saloon.

Self Seal Pipe Insulation 6mm 10mm 13mm 16mm 20mm 25mm 43mm 60mm Foam Tube For Air Conditioner Outdoor Hot And Cold Water Pipe, Lagging Wrap Industrial Covers (Size : ID 60mmx15mmx2m) : Amazon.co.uk: DIY & Tools

Other similar options from UK based vendors if they are local / will ship at sensible prices (Highlands and Islands tax was too high for me):
Google - Class 0 insulation