Hi Folks,

I’m getting ready to install an Espar D4 diesel heater on our C36 Mkii (1999).  My intention is to replace the existing air conditioning duct hose with 90mm high temperature ducting.  Currently there easily accessible pathways for ducting to 3 existing vents. These are located on the port side of the aft cabin (on the wall just forward of the fuel tank access panel and behind the fridge box), mid-ship in the salon area and up to the v-berth.  The AC unit, now removed as we never used it, was located under the seat along the galley wall.  Needless to say that this is where the original AC ducting originates from.

1st question. It is my understanding that the best location for the Espar unit is on the wall in the port side lazarette.  My question is, how to I get ducting from the heater in the lazarette to connect to the ducting located behind the port side wall of the aft cabin?  Or, is there another preferred route?

The only possible route I’ve been able to find is through the small opening below the aft lockers, just forward of the transom just above the skeg area. This would allow me to get the ducting into the port side storage cavity below the aft cabin floor and reach the existing aft cabin AC duct location.  However, this opening is already choked with the two engine ventilation hoses and the exhaust hose.  I doubt very much I’d be able to get a 90mm hose through the remaining space without crushing it.

2nd question.  Does anyone have any ideas if there exists a double walled exhaust through hull which would be suitable for the MKii’s reverse transom.  The alternative would be to mount the through-hull on the port side, in the vicinity of the heater.  For a variety of reasons I understand that this may not be desirable. (Having stated this, the 12 or so boats in our marina with Espar/Wabasto heaters have the exhausts located on the sides and not one has the heater exhaust mounted on the stern.

Any help or advice you can offer me will be of great help.  It’ll be starting to get cold up here in a few weeks.

Many thanks,

Peter Feltham
​