The life of two port valves?

[Burnerman]

My neighbour (oil Rayburn, vented system, S type) is consuming the power heads of these valves quite regularly.....they are lasting maybe 15 months before going AWOL.
So, I fit new Corgi heads onto the Honeywell valve, and away we go for a while.
(I can't say which part is actually failing - no time to test them at present).
I have to say, the power heads do tend to run pretty warm!
Please, any comments about this?
John

 

[dcawkwell]

Don't just change the head change the whole valve.
If the motor and gear are having to work hard against a dirty system and worn stiff valve it will eat them for breakfast.

 

[Burnerman]

Thanks - thats probably my next move if it happens again. The valve did seem quite free to move though, but I don't have a new one to compare it with.
Moving from auto to manual by hand seemed ok.
John

 

[Agile]

Why do you change a head without seeing whats wrong?

I often fit that brand and no particular problems with them.

Until you tell me the failure mode I cannot make any suggestions!

Tony

 

[Burnerman]

Morning Tony, the house in question had no problems with the central heating, but there wasn't any hot water being produced.
I ventured into the loft and felt the 2 port valve feeding the copper cylinder - it was cold.
Manually I opened the valve with the side lever, and immediately hot water surged through, therefore I replaced the power head.
At the same time I replaced the thermostat on the copper cylinder as this was very sticky to turn and didn't seem to switch cleanly, according to my meter.
Everything was working when I left, so I'm waiting to see how long this one lasts!
John

 

[Agile]

Don't you check for an O/C motor?

Far quicker and 1/4 of the cost to just replace the motor if its that failed!

 

[Burnerman]

I may have a play about with the old motor today if I get time.....a speedy replacement was needed at the time!
John

 

[Agile]

Far speedier to just replace with the spare motor that I carry in my Pug 106 !

 

[Burnerman]

Further to this one.....
The motor from the valve I took out yesterday was goosed. I replaced it with a second hand one I had lying around, but the gears started slipping at one point on the quadrant.
Whether its wear on the quadrant or on the motor gear itself I can't really tell, as my eyesight isn't good enough but I'll get a spare motor, pop it in and see what happens.
John