Hey everyone! I'm a newbie to plumbing and I'm having trouble with my setup. I've installed a 12V water pump connected to about 20 feet of piping that supplies water to a shower, toilet, and sink. In the system, there are two T-junctions, and the pump draws from a half-inch tube before connecting to a three-eighths tube for the rest of the run. The weird issue is that the pump works fine at first—I can shower without any problems. However, once it pressurizes, the pump won't restart when I open a tap. Could it be due to the different pipe sizes or something else? I'd really appreciate any guidance! Thanks in advance!
2 Answers
It's tough to diagnose without details about your pump, like its horsepower, outlet size, and rated lift. The reduction from half-inch to three-eighths could definitely be part of the problem. Additionally, consider how far the pipes run and the vertical lift involved; those factors are crucial for a balanced water supply system.
It sounds like you might be dealing with back pressure in your delivery line, which could be preventing the pump from restarting. Try opening more than one tap at a time to see if that helps. Also, if your pump has an adjustable sensor, see if you can tweak the threshold or maybe position a remote sensor closer to the taps or T-junctions. Lastly, if your pipe is flexible, make sure it isn't ballooning, as that might keep pressure up and delay the restart.
Thanks for the reply! I’ve tried opening all the taps at once, but it still doesn’t work. Do you think having those two T-junctions might be an issue, or the change in hose diameter could be affecting it?

For adjusting the sensor, you would generally want to lower the pressure threshold if it’s currently too high—it should kick on with less pressure when a tap opens.