mechanical boiler timer not fully working

[steve084]

hi

i have a potteron promax he plus 24 combi boiler

the problem is have is the timer isnt keeping time it works for a while

but if i go out to work and set it to come on at 5pm i found that the dial has halted at midday or sometime in the nyt

ive got heat the boiler works when i turn it on or if i turn the dial to the correct tim

i just would like to know how to fix the timer so it keeps time correctly

thanks in advance

steve

 

[GuessMan]

There is no adjustment on these timers, you need a new one.

 

[steve084]

is that a expensive job