potterton combi 80 - big leak from the automatic air vent.

[danr76]

hi

this morning, while using the shower with the cold tap running - we need to do this during the winter until we get an inhibitor added to the cold mains, there's not enough gas supply to the boiler (another story) - we suddenly got a big water leak from the boiler (potterton combi 80) which, ages later and after scouring the internet for technical plans of the boiler, i've traced to the top of the Automatic Air Vent. I've stopped the flow of water for now by screwing this vent tight shut

anyone know why this might happen?

with new year looming we panicked and plumped for a £160 callout from british gas, to come sometime tomorrow, but could it just be as simple as a broken seal and a quick replace of that part for less cash? Or something more sinister?

I know literally nothing about boilers, but also couldn't figure why water would still be pouring out hours later, even with the entire water mains closed off

thanks for any info

 

[bengasman]

usual cause is limescale or corrosion, you will need to clean the system, ample info about this on forum

 

[tomy]

it will be the auto air valve needs replacing , this is on your central heating not on the cold water or domestic hot water side hence why it didnt stop when you turned off the mains , it will be draining the central heating . Easy enough job for any competent engineer .Price of auto air valve for potterton 80e £6.16 plus vat and p&p from my suppliers

 

[danr76]

thanks for the replies

time was seriously a factor so we let the british gas engineer come. He barely looked at the aav, instead he said the diverter valve needs replacing ... even though we had hot water AND c/h on call (well, we did until he disabled the boiler and marked it "at risk") ... does this make sense to anyone else?

(I'm about ready to give up on BG - our first booked service guy phoned a fault in as the diverter, then when the engineer came round after that he said the diverter and boiler in general was fine and that our problem was gas supply. And then over a week later we get this new dagnosis of diverter. Aaargh)

 

[mater]

most of bg workers are a waste of time i had 3 different ones to my boiler and they still could not fix it. so i posted the prob on here and namsag told me what was wrong, i showed this to bg man and he fixed the fault ,but he was clueless