"just installed a new freshwater system on demand pump. pump will not run constant, even with multiple spigots open. system pressure seams to go up and down. we have expansion tank but not sure if its doing what its suppose to" ________________________ Sounds like the expansion tank isn't working properly. Check the air pressure at the top, it should be a couple of PSI higher than the pressure in the line, and should go up and down with the pressure. There is a diaphragm in there that may have broken, or the air pressure above the diaphragm may have leaked out. If you can re-pressurize it and it holds, that'll fix it. If not, you may find the top of the tank full of water. You'd have to replace the tank then. Check out Ace hardware; forget the marine stores. Keith _____ If the professor on Gilligan's Island can make a radio out of a coconut, why can't he fix a hole in a boat?