I installed an ancient (20 years?) Eberspacher BN2 in my previous Type 2. 
After installing it I managed to get some circuit diagrams for it and I can 
make copies if anyone is interested. The local dealer representing 
Eberspacher was quite happy to supply a new model for some ?800, (excluding 
fitting) but didn't want anything to do with the BN2.

With a new plug and a modern thermostat, it worked fine. Even in sub-zero 
temperatures (Centigrade), it was rarely on full setting for more than a 
minute or two.

But - I installed it in the space for a second battery and the ducting was 
fed through the firewall, alongside the petrol tank and down into the 
passenger compartment, with an exit under the rear seats. This, I think, was 
one of the standard installations. It was a very tricky job, mainly because 
I used non-flexible metal tubing. What I didn't do was to completely seal 
the seams on the ducting and to fix some insulation between the ducting and 
the petrol tank and this, I would imagine, is ill-advised. Because of this, 
I never ran the heater for any length of time.

Soon afterwards, the vehicle was stolen (North of England).

If you come across an 1,800cc Devon conversion with an Eberspacher heater 
that meets this description, it could well  be mine (or the insurance 
company's).

If you come across an 1,880cc Devon conversion that has exploded, it could 
well have been mine.