O.K I just got done building a wood boiler/ furnace for my garage and I have a couple questions. First one is, I made My own heat exchanger with a fan mounted behind it. What is the switch called that mounts to the copper pipe that turns the fan on when it senses heat in the pipe? Second can I use this HONEYWELL HEAT ONLY THERMOSTAT MODEL CT410B to turn on the circulator pump when the thermostat calls for heat? Any help or advice would be great. Thanks..