what is the danfoss tank for under the bonnet(ex bt transit)?

Hi Tommy. The tank is a hot water heater, there should be another piece of equipment usually under the passenger side below the sliding door which should have 'Eberspacher' on it. This is the heater device, probably be a pump/wiring and pipes also. The thermostat on the dash is the control unit and you'll probably have a fold out sink on 1 of the back doors. If it works, use it if not take it out and stick it on Ebay, they sell quite well.

Joe
February 2009