Let’s explain what a fireman switch does. A fireman switch in conjunction with a timer is used to shut the heater down 15 to 20 minutes before the pump turns off. This was essential for older gas heaters because the old-style firebox retained so much heat. The pump was needed to run water through the heater while the fire break cooled down.
According to Hayward and Raypak, a fireman switch is not required with their new heaters. The new fireboxes are made of silica fiber panels that do not retain heat inside the cabinet. All these newer heaters dissipate heat almost immediately. That being said, it’s not about you, check with your local code requirements. Some municipalities may still require a fireman switch.