Vaillant ecoTEC PLUS 831 re-occuring F22 after being fixed by Vaillant twice

The house I bought already had a 2007 Vaillant ecoTEC PLUS 831 R1 installed.

It had been very reliable for the past 8 years until March 2019 when I regularly got F22.

A Vaillant engineer came out under Vaillants £300 fixed fee repair and found the bottom of the cabinet swimming in water.

He fixed the boiler and "under parts fitted" it said:


The next day the boiler failed and another Vaillant engineer came out and replaced:


Nine months later I got the F22 again and despite getting the pressure back up to 1.5 F22 kept re-occuring.

So I had to get a Vaillant engineer out for another £300 fixed fee and he found the bottom of the cabinet swimming in water again. He replaced:


I asked Vaillant for my second £300 back under their money back if the same problem re-occurs guarantee, but they said no as the faulty items on the January F22 failure were different to the faulty items on the previous F22 failure.

Bearing mind all the parts that were replaced back in March AND a service was done at the same time, I would have expected my boiler to have worked for at least a year before I would need another call out.

Any thoughts ?

I’m concerned as to why on the first visit x2 prv’s(pressure relief valve) were fitted. Were the parts actually leaking? With all those parts fitted I’m surprised it’s leaked again. I would be asking for the money back as well as you have in writing parts changed. Automatic de-aerator? I’m presuming auto air vent on pump. Could be a leak on top of main heat exchanger (seen it a few times) or the plate heat exchanger. Get Vaillant back but ask for a lead engineer?

Edit: just re-read, the connection tube, was it rubber for rubber, or copper for rubber?

Thanks for your interest but I can't answer your questions as I wasn't present when the parts were replaced.

Thanks for all the replies.

I complained to Vaillant and got £155 back.

The boiler is running fine now.

If it fails again I am thinking of cutting my losses by not spending any more trying to keep the Vaillant running and getting an INTERGAS boiler installed with a long guarantee.

Anybody got any thoughts on that ?

There’s a lot of love on here for Intergas. I’ve only helped to fit, commission and fault find on the eco rf30, which are a 5 in 1, which means you can set it up as a different types including combi, heat only, hot water heater.