Hi, hope you can help me. We have a SF 2000 shower/pump and for some reason you can only open it a little bit otherwise it becomes too hot. It is useable, but very difficult to adjust. It is connected, it seems, as per instructions; cold feed from the storage tank in the attic and the hot feed is coming from the hot water cylinder, which is below the unit. As the cylinder as well as the cold water are being supplied through pressure from the height of the storage tank I don't understand why the hot water seems to flow easier to the unit (or am I talking silly here?). I can't see it, but are there normally filters fitted in the unit or should I suspect the mixing valve? Thanks for your advise, Rene.