Vaillant Vantage 150 Hot Water Cutting Out

[marrich]

Our boiler was recently serviced because it had been having a problem with the expansion tank - now fixed. The problem now is that the boiler lights for about 20 seconds before cutting off and the water circulation light comes on. Could this be the mains water feed and if so, what do I do?
Thanks.

 

[crashndie]

dose the central heating work ok ? is the boiler making any kettling sounds ?

 

[marrich]

CH was working but the boiler just fires up and cuts out now. There are some burbling noises. We had the expansion chamber re-pressurised about four weeks ago - wondering whether the unit is caput?

 

[The831Bunny]

I take it you mean the 'egg timer' symbol on the display? If its a black facia Turbomax then the engineer has moved some muck from the expansion vessel into the pressure differential switch/tubes in the boiler. You need to get him back to check the pump is not jammed and/or the PD switch is clean.

 

[marrich]

Thanks for that. Yes, it is the egg timer icon. I had a plumber in today and he has replaced the differential switch and cleaned some tubes. He checked the pump and it's clean and working well. The system re-lit for 15 minutes and then stopped again - cost me over £200 and I now have to decide whether it's worth continuing with diagnostics. Vaillant don't think it's the heat exchanger but rather a bad wire connection somewhere. If anyone has any experience of this, please advise. Don't want to replace the boiler if I can avoid it. I should add it all worked beautifully when the differential switch was bypassed and the pressure in the expansion chamber is spot on.

 

[The831Bunny]

I'm afraid if you are still getting the 'egg timer' light fault there is still a blockage in the PD valve connection tubes. When the pump starts the white lever on top of the PD valve should rise swiftly (no more than 1 second), and when the pump stops should drop just as quickly. If its slower than that, then there's still a blockage. Get him to check BOTH ends of the copper tube that links to the diverter valve. Also the chrome manifold above the pump is another place dirt collects.

Boiler doesn't need replacing!

 

[Bunnyman]

An how come you paid if it ain't fixed ! We all guarantee our work u shouldn't be paying for his trial and error in London try here http://www.vaillantservice.co.uk/VAILLANT/Vailliant_Home_Boiler_Repairs_Servicing_Faults.html

 

[marrich]

Thanks to you both for your advice. He installed a new differential switch and said it was working properly. The boiler lit for about 15 minutes during which time I paid him. It then went back to showing the 'egg timer' and he asked me how far I wanted to go with the diagnostics, saying he could check everything out and still not get it working and it would be throwing good money after bad. He also called Vaillant and carried out a check on the ohm reading for the PCB which he said was at 167 and fine. I'll have a chat with the man on your link and see what his opinion is. Do appreciate your taking the time to help.

 

[marrich]

Have just checked the rise and fall on the differential switch and it is working properly but still no ignition. The manual says to replace the board but the connections were checked yesterday and found good. Have spoken to the receptionist at vaillant.co.uk but will email the engineer for advice.