Webasto water pump as used with the DBW, DW, and the larger Thermo heaters. The pipe fittings on this pump are 38mm.
Some Imported coaches have this pump fitted, but with a different type of plug fitted to it. Eberspacher also use this pump on the large water heaters. A number of coaches are not fitted with a combustion heater, but still have a pump or pumps of this type fitted.