Dave,
I had a 2nd hand one fitted to my van, as I was quoted £800 plus vat for a new one supplied, fitted plumbed in etc etc.
It cost £250 cash, took it to a few mechanics local to me who all said 'no idea mate' in the end a electrical sparky was recommended to me. He fitted it but there are spare wires every where, its not regular, we couldnt work out the timer, how to set it, either temp, timer or what ever as it was digital
They wouldnt help us at the Eberspacher place on the phone, well why would they?
Last year with the big freeze I felt safer with an office type gas fire in there once I realise it had a gastec carbon cut out on it.
Went to the Eberspacher place in the end, it needs a new 'brain' £200.00 also you mate has fitted it illegally there is no vent for it to breathe clean air in and the exhaust has fallen off so it blows exhaust into the van.
Though they said bring it back we will set it up, show you how to use the timer etc etc and make it legal. Oh and your not supposed to have the fuel in a loose can in the back it has to be plumbed into your main diesel tank.
Shall I go on Dave, if I had gone to Eber and paid I would have peace of mind, reliability, warm van, frost free kit, not get up at 3 or 4 to look out of the bedroom window to see if the van is frost free or frozen.
That £200 might be cheap now, but if it goes wrong you will be paying again and again. In more ways than 1.