fireman switch

Hello, I have a Jandy JXi Pool Heater and an Intermatic T101R Mechanical Timer. I would like to add a 56T4042A Heater Control/Fireman Switch. Does anyone know where I connect the fireman switch to the heater? Thank you!

Hello, I am not an expert, but am doing maintenance for a place with a Rheem/Raypack millivolt pool heater in the basement. The other morning I woke up to the sound of a flowing river along with the pump sound the other morning. Luckily I was able to shut it off before too much got wet. Luckily...