[NWH]

Either that or it’s wired up wrong you think you are switching it to hot and it’s wired up for winter.

[robert mitchell]

I think Nigel might be right the switch has been hit and put it into winter mode that reduces the water temperature , it’s easy dine it happens to ours now and again when switching on  the fill valve .

If it is the switch then there is also the possibility that the switch is faulty. If switching the switch doesn't do anything, then I would try removing one of the wires from the switch and see what happens.

I'm presuming the wire would be positive so would need to be made safe when disconnecting it.

I didnt bother reconnecting the summer /winter switch as it says in the handbook if it doesn't get a signal it defaults to the engine off temperature , the higher one.

[robert mitchell]

Could it be a problem with the plate heat exchanger?

[NWH]

Usually when all is working fine and the heat drops it’s the heat exchangers-exchanger,my old single exchanger unit I had did this I changed it and it was back to normal you can’t clean them out with anything they just need changing.

[robert mitchell]

NWH was right , heat exchanger was partially blocked , preventing the webasto going into full heat mode .

Managed to clean it out using a dishwasher tablet dissolved in hot water , left for an hour then flushed with garden hose ......loads of grey sludge came out of the coolant side of the exchanger .

Running spot on now , thanks a for your help .

[NWH]

Everything I post is S**t m8 don’t give me that lol told you pal when you’ve had 1 for as long as I have I can fix them in brail. 👌

[NWH]

And no problem Richard happy to help m8.

[NWH]

Got my V4 thermopure on order m8 👍