Actuator broken?

[Claireabell]

Hi

My radiators don't get hot unless the hot water is also switched on. I'm wondering if the problem is with the actuator (which this morning I knew only as a blue box in the airing cupboard). I've tried looking this up already but can't

I gather that the switch positions are as follows (no sticker on the blue box), please correct me if this is wrong?
Hot Water only = Up
Hot water and Heating = Middle
Heating only = Down

Our switch seems to have different positions, down, middle, and 2/3rds of the way up - it never goes to the top. Is this what they all do or is it broken?

The blue box looks like it has buttons/switches on the other side and the bottom (its in upside down). Are they to remove the cover? I haven't risked touching them yet incase...

Thanks in advance for any replies.
Claire

 

[Claireabell]

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• Claireabell
• 8 Jan 2014
• 1

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• Claireabell
• 8 Jan 2014
• 1

back of box

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• Claireabell
• 8 Jan 2014
• 1

underneath box

 

[Blagard]

Sounds like a micro switch in the head is faulty or the actuator motor.

The fact that you are able to get central heating suggests the actuator is at least working in part because its normal position is with the CH off and the motor has to open the CH port for it to work unless you use the manual vent lever.

One button does release the head from the valve body the other is a lever for manually opening the valve to vent the system when filling and a third shows the position of the valve

Getting a replacement head is probably the answer but when you go shopping for one, check the price of the full valve as well because sometimes the difference is so little its worth having the valve body as well just in case that is a problem or becomes a problem. Some web site seem to charge more for the head on it's own!

It looks similar to a drayton and so pushing the button midway on one side will release the head so you can check the label for a replacement. You have to put the manual lever into the lock position before releasing the head. To do that first push the lever over against a spring pressure, then push the lever towards the valve body as you let go so it latches onto the open locked position.

Here is an example of the Drayton:
http://www.screwfix.com/p/drayton-ma1-679-3-3-port-motorised-valve/81844

Example of head only:
http://www.heatingcontrolsonline.co.../acl-drayton-invensys-ma1-actuator-p-112.html

Installation sheet shows how to remove the head:
http://www.draytoncontrols.co.uk/WorkArea/DownloadAsset.aspx?id=10512

The wiring is replaced like for like as you should find a replacement has the same colours.

 

[Claireabell]

I would have given wiring in a new box a go myself but I wont try to fit a full valve myself, I haven't done pipes/water before. Thats really helpful to know though - thanks for your reply!

The fact that you are able to get central heating suggests the actuator is at least working in part because its normal position is with the CH off and the motor has to open the CH port for it to work unless you use the manual vent lever.

I don't completely understand that, but I did look to see what happened to the position in different circumstances...

Both Heating (H) and Hot Water (HW) off - Up (Remembering that it's 'up' position is only a little higher than the 'middle' position, and not up all the way ??? )

H on - Down (After a min the box made a quiet whirring noise for a few seconds. The pipe leading to the heating and the bottom of the first radiator went a little warm. Boiler didn't 'click on' and usual noises we hear around the house when the heating is working didn't happen.)

Both off again - Stayed Down (Pipe/radiator cooled again.)

HW on - Up (Boiler struck up. Hot water came on)

Both off - Up

Both on - Middle

H on (I just switched the HW off) - Down (Both H and HW switched off)


Sorry for the long list. Can that confirm what the problem is?

 

[Blagard]

The valve is in HW only position in its rest position. With CH and HW the motor moves the valve against a spring to the mid position. With CH only the motor drives the valve all the way over to close the HW port. But when it gets there it hits a micro switch that changes how the boiler is switched on. If the switch is faulty the boiler will not power up. Or if the motor stalls early it fails to operate the micro switch.

The indicator arm on the valve may not be 100% reliable so it may not get fully to position "A" which is I think your down position

The bottom line is replace the head, as I don't think you want to mess about with changing micro switches or actuator motors in side the head. Problems with the valve body are rarer.

Testing the parts inside the head is really the only way to confirm which part is faulty (or not).
Your both off again - stayed down comment suggests to me it is the motor that is jamming occasionally, as it should have returned to up.

 

[Claireabell]

I haven't been here so not fixed yet. I thank you again for you last reply.

I took the actuator off. I could move the valve to different positions easily using my hand. In the down (HW) position the heating did not come on.

Taking the cover of the actuator, a spring and bit of plastic fell out. There was now where visible to indicate where the parts were from but I think?? it might have been the lever to manually open the valve.

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• Claireabell
• 21 Jan 2014
• 1

Bits out of actuator

Once I placed the actuator back in position, the indicator moved freely up to the top in the HW position and no longer gets stuck halfway between the middle and top positions.

From what I *think* I understand, the micro switch is not working. I'm going to order a new actuator today. (Fingers crossed. I thought I'd need a whole new heating system and also replace the old boiler. Along with repairing the shower, the quote from British Gas was £5,500!)
[/img]

 

[Blagard]

Drayton use a pair of springs for the "spring return" mechanism so that would be one of them! It could be that one of the bits was getting in the way and jamming the motor from doing full travel.

It makes me even more sure that just changing the actuator head will solve your problem.

 

[Agile]

Your pump is also at the wrong angle.

The shaft should be horizontal!

Tony

 

[Claireabell]

Your pump is also at the wrong angle.

The shaft should be horizontal!

Tony

Hi Tony

Is the pump the silver/grey coloured part? If so I think it's been that way probably since the house was built. It's not something I can change myself. One of the things that'll get sorted out when we (finally) have a new heating system with combi boiler... I guess.

I wonder if trainees were left to their own devices back when this house was built !

 

[Claireabell]

Many thanks Blagard

I replaced the head yesterday morning and the problem is fixed.

Claire

 

[Blagard]

Excellent news - Thanks for the feedback

 

[chantelle]

Excellent news - Thanks for the feedback

Painfully drawn out. Could have just said `change the head`.