On a manual pool and spa system with valves (i.e., one with no automation), when most owners want to use the spa, they will turn the suction and return valves over from ‘pool’ to ‘spa,’ and flip on the heater.
When they’re done, they turn off the heater, flip the valves back to ‘pool,’ and shut the pump down. However, that allows hot water to sit inside the pipes and the heater, which can cause heat damage to various parts of the system.
Instead, explain to your customers that after they shut down the heater and flip the valves back to ‘pool,’ they should leave the pump running for about a half hour to cool down the water that’s circulating. This is what a Fireman Switch does on an automated system; it keeps the water circulating for a few minutes, so it can cool back down.
— Bryan Chrissan, owner, Clear Valley Pool and Spa Service & Repair, Temecula, Calif.