my vaillant turbomax plus 824e boiler jump out f22 fault code a lot times.but the water pressure stay on 1.5 bar all time. Why?

mr pang, August 2015

The reading on the pressure gauge might not be accurate
I would drain all water from the boiler and see if needle on pressure gauge DROPS
If needle still shows pressure in boiler after draining all water then the pressure gauge is defective hence F22 fault
There are other causes of F22 but I would try this first

Q, August 2015

You must have missed this when you did a search to try and help yourself before asking us: http://www.vaillantservice.co.uk/Vaillant_Fault_Codes.html

F.22 Dry fire, low water in system/Overheat

See this, which may also be useful: http://www.justanswer.com/uk-plumbing/7jyg6-vaillant-turbomax-plus-828e-pressure-1-5.html

XXX, August 2015