Wshisper switch ( limit switch on damper shaft)

The switch you are describing is probably a "whisker switch," a type of limit switch that has a wire projecting from it so that if an object presses on the wire, it operates the switch. As with any limit switch, this can be set up to detect whether dampers, doors, boxes on a conveyor, or whatever are in the correct position to allow the next action to happen (or prevent a wrong action from occurring).

Still,

i am reaserching it. shall i talk to a control contractor or to the manufacturer of the damper?

this is a reverse approach we are talking about.

installing a switch on the shaft side of the motor, so only if there is a physical contact is established between the damper and the shaft ,

than the signal will be transferred to the boiler to get started.

Boiler's can be dangerous, requiring many safeguards, including the one Tornado mentioned.

It is good that you have Government regulation.

In this example, I think the limit switch should be arranged to detect the position of the damper itself. That way it will protect against breakage or loosening of anything in the linkage, not just a broken shaft or malfunctioning damper motor. You don't want a flareback in your boiler!

I agree. Damper position is the critical part -- not the damper motor.

Iam assuming your boiler is large. The damper supplier should fit status switches. These can be conventional limit switches or proximity sensor type. To ensure the drive end shaft is not broken, put the switches on the other end of the shaft. (The damper supplier should tell you this).

If you have any problems getting the info from your damper supplier, send a note on the forum and I may be able to get hold of more info as I spent many years working for US, UK and German suppliers of large dampers. (I am semi-retired now).

i spoke to the pottorf dampers and they told me that they could install a mercury end switch on the shaft side of the motor, which would show whether the damper is open or not and than the switch can be wired to.

is it the right one.. i am confused. so many terminology here.