I have two aquastats. One says r-b opens,r-w closes on temp increase, the other says switch opens on temp increase. The one that says open on temp increase, does that mean that it is the low side and allows the hot water to flow or is it the other way around. I am trying to figure which one is the low side to start the circulator pump and which one shuts it off. Thanks
Electrically speaking, when a switch closes, it allows current to flow in a circuit. When a switch opens, current stops. Think of a light switch. When you flip it to on you are closing the switch. When you switch it to off you are opening the switch. Typically the pump will be controlled by the demand for heat; when the thermostat says heat the building, the pump starts up. If there is not enough heat, the boiler will fire. When there is enough heat in the boiler, the switch that opens on temp increase will kill the fire. You DO NOT want the opens on temp increase on your pump; you want the Close on Temp increase on the pump. Be sure all safety switches on the boiler function properly; high temp cutout, low water, high pressure cutout, high pressure relieve valve.
