806 Hdi Webasco parking heater?

I have an 806 Hdi. Only had it a few months. Have just noticed that it has
what appears to be a Webasco supplementary cooling system water pre-heater.
Diesel fuelled and even has it's own exhaust! Do all Hdi Peugeot 806
engines have this as standard or have I unwittingly bought a used car with a
cabin/parking heater installed as an extra?

It is installed under the bonnet on the off side just by the washer top up
spout.

 

I think this is a aftermarket installation,
(could be wrong though,)
I fitted quite a few of these webascos to 7 series BMWs back in the 80s,
they where computer controlled and set to warm up the inside of the car 1
hour or so before the vehicle was used,
Fitzy

 

this is factory fitted as the hdi engine is so thermally efficient it needs
help to heat such a large cabin space