I agree that this is not common or usual. I get a good hot shower no matter if I'm using city connection or tank and pump. I have found that if you turn the hot water on all the way, let it get hot before you start mixing cold in, it works better. Ours at least did this. When I turned the water on with both some hot and cold and planned on adjusting temp like I did with the shower in our house, seems like I had hot/cold especially if I shut the showerhead off then turned it back on. Starting the shower as indicated above with all hot until hot, then add cold took care of that problem.