Vaillant EcoTec Plus 831 rising pressure issues..

[zahid]

Hi All,

I hope you can help identify the problem with my Vaillant 831. I've had it for about 5years with no probelems but the code F75 appeared. The plumber could not get here so said to increase the pressure in the boiler which did the trick.

When he did arrive he said the sensor was ok but the fault was with both the filling loop valves which were leaking. He said in his 30yr experience he'd never seen both leak.

However, to stop the F75 code, I have to increase the pressure, the pressure rises very quickly (to the end of the guage)..I then release pressure after a few days but have to put more than the amount which would trigger the F75..and so the cycle continues.

Is it as simple as dodgy valves??

Thanks in advance

Zahid

 

[simond]

Well he could be right.

But then again it could very easily be a failed expansion vessel.

 

[Bunnyman]

Stop messin get a decent engineer an change the sensor ffs!!

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[Nitax]

Help Vaillant 831 boiler F.75 fault and rising pressure. 1st I changed the Pressure sensor - worked no more F.75.. 2nd rising pressure so fitted a new expansion vessel - Pressure rises from low in the grey to max in approx 1 week. Have i missed something - should i pressure the new internal vessel up or as i assumed are they factory set. .... Or Any ideas on what else this could be as so far all this has cost a fortune and this boiler has never been reliable in the five years of having it. Help Please.

 

[Bunnyman]

That's what happens I'm afraid when non engineers mess with stuff! This boiler is the best on the market if looked after properly, what on earth made u waste ur money on a exp vessel! Change the fill loop taps there passing! Leave the vessel alone .. U should have goggled Vaillant repairs Northampton. Pay a specialist!!

 

[Nitax]

Thanks for that Bunnyman. I did get a heating engineer to diagnose and do the work - he said it was the expansion vessel - so ordered the part and fitted it - i did look at your responses to other issues and tried to tell him what i had read but he said he knew what he was doing but no i am drained of cash with a boiler that keeps rising - how much it gonna cost me to have this fixed by you!

 

[Bunnyman]

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