The boiler is a sim I'm at my sons at he moment so don't know the model at the moment, and the flow pressure is 12 cups, I have added 2 more shower rooms that is what has caused the problem , but as. Said before this boiler has always been rubbish
the Zanzibar we had originally was a 100 times better. But I have had this one for a long time., I just put up with it.