memes

In seriousness, it’s often about water pressure and how your hot water is fed. If you have very high water pressure normally but a solar hot water system where gravity and input pressure play a role, you’ll naturally have an imbalance on hot and cold. When you turn the handle on the shower you’re lining up two holes in the shower cartridge (in the handle) with the two hot and cold water pipes, the resulting mix comes out a third hole which feeds the shower head. As you turn the handle, one hole opening gets smaller and the other bigger- thereby changing the ratio of hot : cold. When you already have a huge pressure of cold water pumping in, the degree of rotation needed to go from warm/almost just right to PURE HOT WATER is minuscule. Usually the cold will stay pretty cold for about half of the handle range of motion too.

If water input pressure being high is a problem you can put a reducing valve on your system overall or you can buy Venturi style pumps which add pressure into your hot water system.

You’ll normally find when it’s pressure imbalance that it’s easier to balance the temp when the tap isn’t open full bore. But who wants a weak-ass shower stream!!