why are actuators dying

[dazza]

ok i replaced my actuator after about a year of turning the valve manually with a pair of pliers.
i replaced the old satchwell with a sunvic dm5601 wich i was told was a straight replacement. i wired it up and tested it without fixing it to the valve and it seemed to work fine, so i fixed it to the valve and a few hours later it no longer works! is it likely that it was faulty when i brought it or has something caused it to die on me? the valve moves freely so i dont think that has caused it to burn out.
when i took it back off i tapped it and as i did it buzzed and seemed to move for a second or two then stopped.

any help appreciated

 

[AlanE]

Without knowing what has failed hard to say BUT spring return motorised valves should NEVER be operated without the valve attached.

Why? They work on the principle of the motor running until the valve is fully open, can move no more, then the motor stalls - still receiving curent.

Run it without the valve and it will not know when to stop. The gears can get out of sync, cam can get out of sync with the microswitches or the mechanism can just be strained by working on an area of the gearing where it was never designed to work.

Alan

 

[dazza]

when turning the valve by hand you can rotate the d shaped pin around and around so how does it know when to stop ?

is there anyway to test what is nackered on the actuator or have i got to spend another £50? hope not!

cheers

 

[namsag]

On satchwell/sunvic heads if you tighten the two screws that hold it in place down too tight this can cause it to quickly burn out(not usually that quick though), same if you put a screw driver into the slot on the actuator head and force it this will knacker the head. These heads are usually motor on motor off so no damage will have have been done by testing it off body.

 

[MANDATE]

If you have to use pliers to turn the valve spindle, I would suggest the spindle is too tight. To me the spindle should be able to be turned using finger and thumb and without resistance. If the resistance is too great then the actuator motor can't do its job.

 

[corgiman]

MANDATE is perfectly right

what the problem is, most likely, is your system is sludged up and this is sticking the valve body, SUNVIC/DAMFOSS are prone to this due to thier design.

flush the system and replace the valve body