Sticking Actuator

[xraymtb]

Recently been having problems with the hot water not turning off when it should.

Noticed that when it comes on the actuator (the system has two 2-way valves - one for CH one for HW) on the hot water feed clicks loudly and does not return when the water should go off.

This seems to also keep the boiler running until the valve is closed.

I've had the cover off the actuator and it looks ok but still didnt close until I pushed the little arm to close it.

Even with the power to the controller off, the water will stay on until either the valve closes or the boiler is turned off.

Any ideas? Is it as simple as replacing the actuator?

Its a Siemens DVA2/5 actuator.

 

[penfold46]

With the actuator head removed, how easy can you move the spindle on the valve body?

It should easily twist with you hand, and if it cannot you would be advised to replace the valve body.

Does the actuator work with it detached from the valve body? IIRC, these valves have a synchron motor inside which could need replacing.

 

[xraymtb]

I've not had the whole head off, just the cover.

I presume removing the head is as simple as a couple of screws?

I think the valve body is turning ok as the valve will open without any problems if it is closed and the HW comes on but I'll check it tonight.

 

[penfold46]

I presume removing the head is as simple as a couple of screws?

It should be, but be careful as not all valve heads can be removed without causing a flood.

 

[Agile]

Have you checked that the cylinder stat is turning off? Sounds not! Stat should be set at 55-60.

Tony