This thermal switch closes when the HE440 is at a steam producing temperature. The mounting holes are spaced 1". The two electrical contacts are Â¼" male quick connect terminals. Mounts inside the HE440 control panel on the tank wall.
We bench tested this switch with an ohm meter and a bic lighter. We held the flame an 1" away from the upside down switch and in 5 seconds the switch would close and stay closed until it was almost back to room temperature.
For HE440 wiring info, see the schematic on page 11 of the HE440 Product DataÂ manual.