I found this reference to the heater on an obscure web page -


'The auxiliary heater (Zusatzheizung, code 228) is a separate heating
system that works independently of the engine. It consists of a
separate burner unit, an electric water pump, a control unit and it
is connected to the coolant circulation of the engine. It is run on
the fuel of the car (either diesel or petrol, these are different
units for obvious reasons) with a separate fuel line from the tank.
This makes it independent from an electrical outlet and from the
engine. It is started either manually, with a timer (mounted on the
center console or in the glove box) or via a powerful FM-wireless
remote (the Mercedes units for from about 500 to 1000 meters
depending on local circumstances. The latest versions are available
with mobile phone remote control as well.

Once it is started, a spark plug ignites the burner which heats the
coolant up and the water pump recirculates the water through the
engine. The system heats the coolant up to 80°C and works until that
temperature is held in circulation. Once the temperature of 55°C is
achieved, a separate relay starts the heater blower and this heats up
the interior.

Even at very low temperatures in Alpine or Siberian regions, this
heats up the engine and the interior within 20-30 minutes. Apart from
a warm seat when you step in, the heat melts all snow and ice on the
windows without further ado.

Very comfortable and a must in Southern Germany, Switzerland and
Austria.

Many German Taxis have it as well since it helps them keep warm in
Winter when the wait and have no engine running.'

I still need some info to get mine working as well as instructions so if this rings a bell with anyone I'd love to know.
Thanks

Toby.

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tobyd uk
94 E280T