Myson 2 port zone valve

esox28 wrote: »

Dpl stock mison heads, bout a tener cheeper.

Found two of these actuators, Myson Power Extra..Model MPE222, stuck in the open position in my daughters house a few days ago. I was able to free them up by forcing the manual lever towards the Auto position, I then powered them on/off a number of times and they seemed OK. These valves hadnt been exercised for about 3 years, one is zoning the downstairs rads, the other zones the upstairs rads, there is no motorised valve on the DHW cylinder. From now on, the upstairs zone valve will be modulating a few times per day so it will be interesting to see if it continues to works OK. I have a Honeywell motorised valve which has a metal cover which dissipates the 7 or 8 watts heat build up, the Myson is "plastic", I wonder is the heat building up inside the motor/gearbox and hardening the grease/lubricant?. I measured the power drawn by the myson actuators and both were 7 to 8 watts. I was surprised that I could open/close the valve spindle(s) with my fingers so these certainly were not the cause of the problem.

Its interesting; your point about the interlocking, there is no room stat, just a timer, the two actuators are manually controlled from two switches mounted adjacent to this timer. They are either wired independently or wired from the permentantly live side of the timer as they stay on when the timer has timed out or is switched off manually. The house was built 10 years ago so I reckon that if they had been wired properly? then two new actuators could be purchased from the power saving. As the downstairs zoning is never required off I might remove the actuator completely and just put the valve in the open position. I dont know if I can rewire the actuator(s) supply to the output side of the timer due to lack of access but I'll have a look. Of course the extra switching might shorten the live of the actuator, the present ones have lasted for 10 years and, hopefully, still counting.

The link below gives some insight into actuator failures.

http://www.seered.co.uk/sunvic_detailed_failure.htm