Description
The MSTN is a motor switch terminal from Resideo (Honeywell Home), 24 V AC, 6 VA.
It is the end switch half of a zone valve: the contact that tells the panel the valve has finished opening. A panel that starts the circulator on the call rather than on the end switch runs the pump against a valve that has not moved yet.
This is a service part. The valve body and the motor stay where they are, so the repair is a terminal change rather than cutting a valve out of the pipe.
A zone that heats but never lets the boiler fire, or one where the circulator runs before the valve has opened, is usually this contact rather than the valve.
- Brand: Resideo (Honeywell Home)
- Manufacturer Part #: MSTN/U
- Type: Motor switch terminal
- Rating: 24 V AC, 6 VA
- UPC: 085267260138
- Category: Replacement Actuators