Fixing a shower water temperature that surges unpredictably between hot and cold requires servicing the internal valve mechanism. In most cases, the culprit is a worn-out or mineral-fouled pressure-balancing cartridge spool inside the mixing valve that fails to balance hot and cold water pressure fluctuations. To fix this, shut off the main water supply, pull out the old mixing cartridge, clean away any trapped debris or scale, and install an exact-matching replacement cartridge. Verification: Turn the water back on and test the shower handle through multiple mixing cycles.
1 votes
Marked as accepted