I’ve been considering which heater type to buy for about 14 years. On that basis I think I’ve decided you don’t need one in this country! I’ve yet to take little’un in anything other than mid-summer though so things could change.
This is a bit of thread revival, but I have a complete BN4 with two of the bits you are after, I’m not likely to use anyof it as I am fitting a newer diesel Eberspacher D2 instead. I may put up a for sale post soon.