combi heater won't kick in , Vaillant vcw 18 t3w

[House123]

Went on holiday and turned water off in the house. Since coming back off the holiday , water is back on but combi won't kick in when activated by timer or by hot water tap being turned on. The pilot is on .

 

[Agile]

And the boiler pressure is ???

There is an overheat stat inside the boiler casing. That would stop the boiler firing but the pump would still run.

Tony

 

[Bunnyman]

Tony if overheat trips pump does not run on this model! Prob pump stuck if it's bin off for couple of weeks

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• Bunnyman
• 26 Mar 2010
• 499

 

[House123]

Checked the pressure and its 1 bar. Timer is ticking so I take it is working.No reaction to timer going on constant, or by adjusting the room stat. Thanks for any replies !

 

[Bunnyman]

I did answer ur post mate prob stuck pump undo centre screw an turn impelor with smaller screwdriver see if it's stuck

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[House123]

Thanks Bunnyman. have checked the pump and its not stuck, no problems moving. Have also checked electricity to boiler and its juiced up so fault could be more serious. Thanks for everybodys replys .

 

[Bunnyman]

these r very sensitive if the pilots on it can still have tripped the 2 switches in switch box hence no power...push red button

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• Bunnyman
• 26 Mar 2010
• 499

to turn pilot off wait 30 secs or so for a click them go through relighting procedure..this r resets the electrics

 

[House123]

Have just done the relighting procedure but no change . Any more suggestions Bunnyman ?
Thanks .

 

[Agile]

Sorry if I am going back but have you actually checked that the overheat stat is NOT tripped?

Tony

 

[House123]

Thanks for replying Agile it is appreciated. I haven't check the overheat stat is tripped. How can you tell if its tripped, and if so how would you reset it ?

 

[Agile]

Its towards the back on the right hand side of the the metal PCB box and is inside a rubber dust cover.

You have to push it towards the left to reset it. Best to use a piece of wood or similar as its difficult to get your hand to it.

Tony

 

[House123]

Thanks for the advice Agile ( Tony) will give it a go and get back to you.
Thanks House 123

 

[House123]

Got inside the metal pcb box , cannot see any switch on the rh side. I see the pcb on the lh side, the micro switches on the centre the only thing I can see on the rh side is something like a bell with RANDO on its side and this has no switch or moveable part. Hope this explains what I'm looking at . Would appreciate you continued help Tony .

 

[Agile]

Its towards the back on the right hand side of the the metal PCB box and is inside a rubber dust cover.

You have to push it towards the left to reset it. Best to use a piece of wood or similar as its difficult to get your hand to it.

Tony

Its reset from the OUTSIDE !!!

The rubber cover is visible from the front of the boiler.

Tony

 

[House123]

Sorry mate you must think I'm a right one. Can see a rubber nipple at the back rh side of the outside of the pcb metal case. Would this be it? Do I have to have power to the boiler to reset ? As I have the front of the pcb box open is there anything i should check. there are 2 fuses in a little black plastic box to the right of the metal pcb box. Thanks for your replies. Keep the faith !