Why a Heater Bypass Valve is a Good Thing to Have
Many pools have a heater in their water flow. Water circulates through the heater core all the time the pump is running, whether the heater is on or off. If the heater springs a leak, you have to shutdown the pump, which stop waters circulation, filtering and chlorinating your pool. Having the pump stopped too long can lead to algae and a dirty pool, and more work once you get the heater repaired and the pump running again.
If you had a heater bypass valve you would just move it the bypass position and you can continue running the pump and circulating pool water normally while you get the heater repaired or replaced.
With a relatively new pool or heater you may not see a leak for many years and wish you had a heater bypass valve. However you may encounter another situation where bypassing the heater is helpful. Heater cores can be damaged by acidic low pH below 7. Maybe you misjudged your acid addition and accidentally lowered your pH too much, If you have a heater bypass you can turn the valve and stop the acidic water from flowing through the heater. Or maybe you purposely lower the pH to around 7 to treat a scale problem. You can use the heater bypass valve to take the heater offline and protect the core.
