Valve Actuator faulty: what to do?

[Cateye]

Hey guys,

I hope you can help me with this. We recently became home owners and are now experiencing the joy of having to fix everything ourselves. Most things that came up so far, were pretty easy to handle, but a few days ago the Valve Actuator at our Gas boiler started acting up. It made a clicking sound every time we turned on the power. I've had a look and switched it to manual control, which opened the valve and the clicking stopped. Yesterday, after we switched off the boiler, I heard that the switch slowly turned back to "Auto"-Mode and this morning the clicking was there again. I've tried to put it back to manual, but it doesn't stay there. The boiler still works and we get heating and hot water, which leads me to believe that the valve is actually still open (?), but the actuator seems to have some mechanical problem - but I'm no expert on this, so I thought it might be best, to ask for some advice.

We have a Siemens demountable Actuator DVA2/5. I opened it up today and took a video of it, to show what is happening (also took a video of showing how the switch doesn't stay in place the minute I turn on the power). I'm just wondering if anyone has advice on how to fix this. Is it just the actuator (which I hope) that needs replacement or do I need to actually replace the valve too (which I won't be comfortable doing on my own to be honest...).

Video of Actuator making the switching sound:

Video of Switch jumping back to "Auto" when Power is on:

Any advice on this is greatly appreciated. Thanks!

 

[terryplumb]

Replace the actuator ,it's duff.

 

[Gasguru]

The valve is only locked into the manual position for draining down and refilling...it leaves the valve partially open.
It looks like the gears are slipping..cut the power and take off the actuator...can you see worn teeth causing the slippage.

 

[Cateye]

Thank you for your quick reply. I took the actuator off and the teeth are definitely worn (see: https://postimg.cc/R3nGYyDv ). So I assume it might be best to can change it with the same model? Like this one: https://www.gasparts.ie/product/siemens-dva25

 

[terryplumb]

If your existing valve has the code CZV 222 ,the one you linked would be a direct replacement.

 

[Cateye]

It has, I'll oder the replacement then. Thank you all! This has been very helpful.

 

[oldbuffer]

If you intend to fit the replacement yourself, then assuming it is connected via a wiring centre:
1. Make sure there is no power to the wiring centre. It may not use the same switch as the boiler, so best to turn off at the consumer unit if possible. Use a multi-meter or a non-contact voltage detector to check no voltage is present. Once you have checked the wiring centre, test the multi-meter / voltage connector against a known mains voltage to be sure it is working. A neon screwdriver is not enough.
2. Cut the wire coming from the old valve at the wiring centre end, leaving an inch of wire still in the wiring centre, with the colour coded insulation on it.
3. Replace each stub of wire from the old with the same colour wire from the new, discarding the stub of old wire as you go. This makes sure you wire the new on a like for like basis.

 

[Cateye]

Thanks @oldbuffer, that's very helpful! I'll definitely check everything with the multi-meter. Leaving the old wiring stubs to not get confused with the colours, is great advice. Parts arrived today, so I hope to get it done over the weekend.

 

[Cateye]

Finally got to it - all is working well now. Thanks again for all the help.