Faulty mid position valve?

[OllieN]

When the hot water comes on my radiators get hot.

Prime suspect is the ACL Drayton Lifestyle 679H340-30L0 mid position valve. I can see that the little black position indicator in the right will move between the H and M positions but will not make it over as far as the W side. When the hot water is on I can manually move the little black lever to the W position (which is the side of the valve that then exits to the coil in the cylinder). So I'm pretty sure that the motor is shot. However I'm not convinced that the valve is working correctly even with that lever pushed to W as it still appears that water flows out of both exits (I'm not 100% as I always get home to test it when the pipes are already warm, but I think this is the case). I presume this is a fairly open and shut case of faulty valve? or is there another possibility.

Am I right in thinking that the ACL Drayton Lifestyle 679H340-30L0 doesn't have a replaceable head so I'm going to have to get someone in to change tha valve (If it were just the head I'd have a go myself being an electrical engineer), or is there something I could do myself?

If it does need replacing is that a full system drain down or can they just isolate and drain to below the level of the valve (Its on the top floor of a 3 floor townhouse, there is an isolatinv valve between it and the pump which is directly below it but not to the cylinder coil or heating circuit.

Thanks in advance

 

[seco services]

i wouldn't suspect a motor failure as the motor is winding the valve over.
on hw only the motor don't play a part it fails back to relaxed position by a spring (W)
check the spring inside and also the valve spindle may be stiff.
on the opersite site of the indicator is a black button push it in and the actuator will lift off.
to gain access to the spring remove the screw on the end and the cover lifts off.

 

[OllieN]

Thanks for the info.

There's no black push button on the side - I think its an older model that didn't have a lift off actuator. I'll try and disassemble and see if the spindle is stuck or what's going on with the spring.

 

[45yearsagasman]

I wouldn't bother in trying to repair this older ACL valve.Replacing it is straightforward and you only need to part drain system to below the valve to change.Dimensions and nut sizes are the same.

 

[combispecialist]

agree with 45yold,a full new valve is req'd,straightforward job

 

[twgas]

I don't entirely agree with previouse answers, you (OP) said;

I can see that the little black position indicator in the right will move between the H and M positions but will not make it over as far as the W side.

this would indicate to me that there may be power going to the white wire all the time and so not allowing the CH port to close.

 

[seco services]

I don't entirely agree with previouse answers, you (OP) said;

I can see that the little black position indicator in the right will move between the H and M positions but will not make it over as far as the W side.

this would indicate to me that there may be power going to the white wire all the time and so not allowing the CH port to close.

so why is it not sitting on the M position.

I can manually move the little black lever to the W position

power on the white wouldn't allow you to do this.

 

[twgas]

I don't entirely agree with previouse answers, you (OP) said;

I can see that the little black position indicator in the right will move between the H and M positions but will not make it over as far as the W side.

this would indicate to me that there may be power going to the white wire all the time and so not allowing the CH port to close.

so why is it not sitting on the M position.

I read it as being either at M or H, not continuously moving back and forth, as I believe you have read it.

I've never tried moving the lever or indicator back to W (well not that I remember )

 

[seco services]

I read it as being either at M or H,

yes it is till he asks for hw only.
then the valve won't fall back to relaxed under it's own steam only by helping it.

thats what i made of it.

 

[twgas]

I would say that if it springs back to M after being on H it suggeste the sspindle is not stuck and the spring is working, hence the conclusion there is power on the white.

 

[seco services]

I would say that if it springs back to M after being on H it suggeste the sspindle is not stuck

no not stuck but i would say getting stiff on that position of the valve.

and the spring is working, hence the conclusion there is power on the white.

i'm not swaying for power still on the white.

surpose we'll never find out as he's changing complete valve.
unless as you say power still on the white then the new valve will play up to.

 

[OllieN]

It requires a fair amount of force to get the lever over to W, but once it is over there it stays there so the spindle could be a little stiff.

The lever stays still at either H or M under the normal operation, so H for heating only, and M for all other options, including HW only. Is doesn't oscillate between positions when at one setting if thats what you were getting at.

Presumably I could test the power on white theory before getting the valve changed by calling for heating then switching off all power to the house, If I understand what you are saying then the spring would then attempt to bring the valve back to W once all power had been removed? - In the absence of a multimeter

edit: I have a little time to figure this out as we have a busy weekend and week coming up so It'll almost certainly be a week or so before I get someone in to do any work - plus I have a curious mind and like to understand these things.

 

[seco services]

It requires a fair amount of force to get the lever over to W, but once it is over there it stays there so the spindle could be a little stiff.

thats what i recon.

Is doesn't oscillate between positions when at one setting if thats what you were getting at.

i didn't think so.
Presumably I could test the power on white theory before getting the valve changed by calling for heating then switching off all power to the house,
[/quote] don't turn all the power off cause you won't get a power then.
only the hw on heating off.
but i don't think it's getting power when it shouldn't.

If I understand what you are saying then the spring would then attempt to bring the valve back to W once all power had been removed? - In the absence of a multimeter

yes

i'm sticking with what i said before sticky spindle or the spring is failing.

take the top cover off and you can watch the valve in operation and see the springs etc.

 

[OllieN]

Thanks everyone. This is quite interesting.

I'm in several minds..

On the one hand the valve always stops dead on M position when moving from H to W and then if I move it manually towards W it will stay wherever I release it which would I guess be consistent with a stalled motor (power on white?). If it were a spring or spindle problem would it not be more likely to be failing at a varying position?

On the other hand I'm still to decide if the valve body is actually working even when I manually set it to H, I shall try again tonight to get home before the HW comes on and heats all the pipes.

I think I shall get one of those mains tester screwdrivers on the way home tonight as they're only a few quid, would be useful to have one around, and I can then easily prove or disprove the power on white theorey.

Thanks all for you time and contributions, its a good practical learning experience.

 

[seco services]

If it were a spring or spindle problem would it not be more likely to be failing at a varying position?

not always seen them jam or still in some funny positions.

On the other hand I'm still to decide if the valve body is actually working even when I manually set it to H, I shall try again tonight to get home before the HW comes on and heats all the pipes.

ok