Vaillant actuator motor not actuating

[BlueUrbanSky]

Hi, new member to this forum. Its always been a good source of info.

I had a leaky diverter on a Vaillant 831, and the hot water had stopped working while the CH was fine. So no problem change the diverter, leak is fixed but still no hot water...

Checked a few other bits, the HW heat exchanger is fine and so is the filter by the pressure sensor, removed deposits from rubber pipe section.

with the heating off, and the actuator dangling loose it is fully extended in CH mode. turning the boiler on produces 2 bursts of vibration (presumably to push out for CH) using mode 6 (to put the diverter in half half mode) there is no movement and no vibration, similarly if HW is demanded there is no movement.

In the diagnostics all appears to be working fine, it is telling me that the diverter is in the correct position at the correct times pumps and temps all correct but still no movement of the actual actuator.

Due to the motors being PWM driven I cant test to see if the motor is at fault or the PCB, while it is inactive the voltage stands at ~20v on 2 poles ~3v on another and 0v on the last. Continuity through all wires is fine. the old motor also behaves the same.

any ideas?

 

[ScottishGasMan]

Call an expirienced RGI in to fix it.

No DIY Gas Answers allowed on here, and as you have disturbed a sealed air chamber it requires specific tests/checks that need to be performed by someone with the correct tools and qulifications.

 

[BlueUrbanSky]

No gas chambers disturbed, no gas involved at all. Looking for info on an electric motor.

 

[ScottishGasMan]

The front cover of that boiler is a sealed unit, that has an effect on combustion. And it must be removed to get to the electric motor (or any component)

 

[BlueUrbanSky]

Its designed to create a vacuum drawing air through the flue. I would presume that this is in aid of a sealed room design, to reclaim heat from the exhaust and prevent back flow of gasses (tho with fan over run this should be negligible). If this is against forum rules I apologise I am happy to leave the discussion, looking at other threads I thought it would be within the guidelines.

Ideally I would like to know if there is an easy way to test the motor that is sitting on my work bench?

 

[Bunnyman]

What u have written re the case is incorrect It is a sealed unit, as said so u shouldn't be changing the diverter, ur pcb is ******ed

 

[BlueUrbanSky]

Ty bunnyman, thought as much.

 

[BlueUrbanSky]

Just to close the thread. The symptoms were a diverter actuator/stepper motor not changing position even tho it would buzz on startup. It was the main PCB that was causing the issue. No visible defects to it just malfunctioning.

Replacement can be had from Ebay at around £80 under the part number 0020132764 + fitting by a gas safe plumber.