Hi, welcome to Just answer
How old is it ?
Feb this year
still under warranty ?
As you have already tried to reset it three times with no luck the problem seems to be with the flame sensor
F29 error indicates a flame sensing fault which indicates that gas is available but the flame will not come up for the unit to start
as it is under warranty it is better to get it checked by a Vaillant Tech.
You can contact them at 01773 828100 to book repair
Is there not something that can be done from the meter? Thelast time this happened the plumber did something at the meter and charged me 50 quid.
usually F28 is displayed when the external pipework is blocked under extreme cold conditions...I dont think it will help this time as both F28 and 29 are flashing which indicate Ignition or flame fault, it is better to get it done under warranty
you may try to open the gas supply as well for few times before it kicks in again
if the fault is still there please get it done under warranty
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