Vaillant 242 prob! Maybe PCB!!

[Jimbobplumb]

Hi guys!

Hope someone out there can help me with this!

When i turn off the room stat, the heating goes off, when i trun the room stat up, the heating will not start back up at all. If i run the hot tap, the boiler heats the water and when i turn the tap off the heating starts back up...but after a couple of minutes the boiler shuts down completely. If i reset it, as soon as i turn the room stat down the process starts again!

Its getting on my nerves...im thinking along the lines of a new PCB or could it be something simpler such as a sensor on the heating side?

I appreciate any help you can give me on this )

Jimbob

 

[Agile]

Why does everyone always rush at the PCB ???

Its almost certain to be the system flow switch is not operating reliably on CH.

Tony Glazier

 

[scatmanjohn]

Sometimes it is the pcb that causes that fault. (think its the front one that the other 3 plug into)
Kaput anti cylcing timer me thinks.

Or maybe something else entirely.

 

[geoff@cetltd]

If it's a pcb, it'll be the middle (thermostatic control) pcb

 

[weareleeds]

First place to look is around the diverter valve area for correct mechanical movement both to the right when on dhw & to the left when on htg also there may be too high an electrical resistance through the low voltage switches

 

[Jimbobplumb]

Hey guys!

Thanx for the advice...i will be looking at the boiler again tomorrow...will let u know if its pcb, flow switch or...whatever! )

Cheers and hope the sun keeps shining for all of u!

Jim...

 

[corgigazza]

used to work on contract with loads of these boilers and if its not the micro switches its normally the flame supervision board, turn down the time delay to the minimum. (poteniometer behind silver blanking plug front of main case ) start up heating turn down front control knob to min burner goes out, turn temp to max wait for anticycle time delay, if burner starts check switches if burner does not start replace ig pcb ps do not run hot water while performing this test also have had thermostatic board (pcb with large blue chip on)cause this once.

 

[ChrisR]

Which vaillant 242 - there are about a dozen!!
VCW or VUW for a start!