Sticky Drayton Mid position valve?

[Paul Cockhill]

Hi My Heating is working fine but sometimes the hot water cylinder is not heating up. I have noticed particularly in the morning that the radiators come on when the timer kicks in at 0600 hours, it is set to Hot Water and Heating but there is no hot water. There is a Drayton Mid position actuator and I am wondering if it is sticking to only allow heating?. The hot water turned on last night so could it be a sticking valve. Is there any way of testing it other than replacement. Many thanks Paul

 

[Anton]

If it's sticking, it's most likely to be the valve body rather than the actuator. If you remove the actuator head and try turning the spindle on the valve body that the actuator turns. If you can't move it with your fingers then change the valve.

 

[SteveBathie]

Hi Anton,

I have a similar problem, but it's an opposite symptom - hot water (too hot) all of the time even when I turn the hot water off in the control panel. I tried moving the valve with my fingers and it moves a bit, but I'm not sure it moved enough - should I feel it moving through the centre position, and is it a full 180 degree rotation to go from one stop to the other?

Thanks,

Steve

 

[Corgiguy187]

Service kits are available now for Drayton valves as long as you have the valve with a removable head

 

[kay-jay]

If it's sticking, it's most likely to be the valve body rather than the actuator. If you remove the actuator head and try turning the spindle on the valve body that the actuator turns. If you can't move it with your fingers then change the valve.

It can be sludge debris in your system that is causing the valve to stick. You should rule this out before changing the valve for a new one and still having the same issue....

 

[kay-jay]

Hi Anton,

I have a similar problem, but it's an opposite symptom - hot water (too hot) all of the time even when I turn the hot water off in the control panel. I tried moving the valve with my fingers and it moves a bit, but I'm not sure it moved enough - should I feel it moving through the centre position, and is it a full 180 degree rotation to go from one stop to the other?

Thanks,

Steve

If your water is too hot it is not a fault with the valve! You have a problem with your cylinder thermostat. Either its set incorrectly or just not working. Depending on the age of your system you may not even have a cylinder stat and the temp of your water will then be crudely controlled by the boiler thermostatic output control

 

[Reg Man]

Normally change the valve body with the actuator head, because the valve body is usually the cause, the actuator failing is only the symptom.

 

[jimh1]

Rather out of date advice. The modern (approx 4 yrs old) MA1 has a rubberised flapper in the valve, rather than the old rotating brass piece. So (a) the spindle does NOT rotate completely, the total movement is around 30 deg each way. (I've just sheared one off finding that out - grrh), and (b) it will normally not fail or scale up. In my case the actuator had failed due to a little stub that holds a spring having broken. Clue - the actuator rattles.

 

[Reg Man]

Better get on with it then, our advice not needed.

 

[jimh1]

Better get on with it then, our advice not needed.

Sorry, didn't mean to offend. Just hoping to prevent someone else ruining a perfectly good valve like I did.

 

[Reg Man]

Not offended. But post 7 is sound advice for nearly every valve I've come across. Know some engineers who change just the head only to be called back a month latter with a burnt out motor. You send it back to manufacturer and they say its not covered, because you didn't change the body. Leaving one unhappy customer or you out of pocket.

 

[jimh1]

I have over 40 years experience of these valves, and until recently I would have agreed entirely. But looking at this MA1, fitted in Jan 2008, the structure is completely different (just a rubberised flap which moves 1cm either way to block off the relevant port, or sits between them). I cannot see how it would easily stick . Sure, the spindle might possibly stick, but if it moves the correct amount (about 30 deg either way, NOT 180 deg) then it's fine. I was trying to help someone like the guy in post #3 avoid shearing off the spindle like I did.

But this type of actuator, on the other hand, is a real source of trouble. Have a look at the seered.co.uk website /sunvic.htm (can't post the proper URL ??)

 

[Reg Man]

(Seered)The bloke that has a fetish over Sunvic Valves and slags them and plumbers off. Yer very convincing.