My boiler randomly switches itself off and shows F22 for no reason - ie, it's not empty. There's no reason and comes back to life when the whole thing's switched off then on again.
Any ideas? It's a turbomax plus 824

Debb, January 2008

We found none of that helpful. The water pressure was ok so our plumber told us to turn it off and on again then refire it by pressing the button with a flame (burner symbol). It then restarted .

Robert Williams, December 2016

Its all down to presure. Not enough !

F I Z Z, December 2009

I have a GlowWorm 30CX and was experiencing the same error after bleeding one of the radiators. As mentioned above turning turning the water taps and raising the bar pressure back to what it was (1.0 bar) did the trick. I did have to switch the boiler off and back on to see the bar pressure indicator when opening the water taps.
Thanks for your help saved the cost of a call out!

Terry B, October 2009

All you people who have said the cause of the F22 problem is poor water flow are wrong. If you check the manufacturer's info you will find it suggests quite the opposite - too high a water flow. This is quite rediculous of course but hey, it is a Glow Worm boiler-(strangely enough) so what to you expect. Even the manufacturer cant figure it out.

Aarovic, December 2008

I have had this problem for years. The engineer's have replaced everything, but the random problem continues to occur. The system is clean. The latest excuse if that the system is not powerful enough, but they are not interested in ascertaining fact. I am just a humble user, never designed or installed this system. Any suggestions where to go next ?

Steve Clark, December 2008

Just topup the water by turning two taps in horizontal position and watch the water lever on guage. Once it is reached to one quarter of the grey scale and put the grey guage back to their positions. It should work fine. Thanks

Syed Rizvi, October 2008

After British Gas changed the diverter valve the F22 problem started and the engineers spent 2 weeks changing various parts without success. I referred them to the comments on this site and they changed the pcb. The boiler has now gone 24 hours without an F22! I'll report back if the problem recurs.

Maurice Turner, March 2008

Thanks - I've had three different British Gas engineers trying to sort this out. The last attempt was to replace both the sensors; the pump was ok. I think I'll call them out again and suggest they have a look for dirt in the system

Debb, January 2008

Hope this helps found this on another web page
The code is for a lack of system water flow.

Its measured by the temperature sensors and they can give problem trips if they are a little off tolerance.

The earlier boilers were too sensitive and later PCB software has been modified we are told.

Officially the poor flow is caused by a blocked or weak pump, dirt or air or a blockage in the system.

What the actual cause is in your case is I dont know without being on site. Clearly the "plumber" you had there is rather less than competent! I would suggest you call a boiler engineer!

The link is http://www.diynot.com/forums/viewtopic.php?t=79868

Roger Brown, January 2008