Vaillant 824e turbomax plus

[Mark Knappett]

Hi
The above boiler cuts out regularly. Fault f22. The pressure isn't low and pressing re set works.
I want to change the water pressure sensor but can't find instructions.
Can anyone tell me if this model has one and where it is please.
Thanks.

 

[Gasguru]

If you need instructions to change such a basic part then I'd suggest you are not competent to touch the boiler and should get a qualified eng in.
However, you are unlikely to find a water pressure switch as very few models were fitted with them...but obviously if fitted it's the first item to check.
The fault description for F22 is misleading. The boiler software looks for a specific temperature rise across the heat exchanger versus time etc.
If it's not happy (especially when first firing up) it will throw the error.

A temperature rise issue can be caused by...

Weak/failing pump
Temperature sensors/connectors
Poor flow rates due to blockage somewhere
Ignition burner pressure a little low
Early pcbs with over sensitive software
etc etc.

Once the basics are checked it's worth upping the ignition (low rate) burner pressure above the book value...clearly this and any combustion
chamber related operations MUST be carried out by a qualified eng.

 

[Mark Knappett]

Thanks for that.
I wouldn't touch the gas side but changing parts such as the fan and hot water heat exchanger have been reasonably easy.
It's an old boiler and it's probably time for a new one.

 

[Gasguru]

I'd keep it going as long as possible..they've had a few design issues but nothing compared with much of todays models.
Fan swaps can be just as hazardous....

 

[Mark Knappett]

To be fair it works fine. Just has this annoying habit of needing to be reset once or twice a day. Never in summer though when only the hot water is on. I think your right. I'll leave it as long as possible. I appreciate your help, thankyou.