Bosch Worchester Greenstar Boiler

[BigRooster]

Last year I posted a question about my Bosch worchester greenstar boiler going hot cold when running shower . I changed thermostatic mixer but made no difference.. Once the colder weather came in and heating went on it seemed to have cured it self. But now the weather has warmed up and heating off shower is going hot and cold again so I'm hoping someone has some thoughts on what's going on .

[mrs_overall]

Does it go hot again spontaneously or do you have to press the 'reset' button?

[BigRooster]

Makes no difference if I press reset just strange it's ok when heating is on

[mrs_overall]

Sorry, I can't help - it is a different problem to the one ours has.
Good luck

[BigRooster]

Shall we say that if the shower going for 10 mins it will go cold for about 30 secs maybe 3 times in that period

[BRIGHT SPARK]

From the symptoms it could be a blocked heat exchanger....or the HE temperature sensor.If you're not on a contract sign up for one and call them out after a few weeks.

[BigRooster]

How much do you think it would cost for a heat exchanger to be replaced with out a contract

[BRIGHT SPARK]

How old is the boiler?.The HE is the single most expensive part and could cost between £300-£450.When was it last serviced?.What model is it?

[BigRooster]

Bosch worchester greenstar si/junior serviced by British Gas last August no problems think it's about 9 yrs old

[BRIGHT SPARK]

Call a local WB installer,It may be something simple.Dont use anyone not experienced with WB.

[BigRooster]

Agree anything to do with gas leave it to experts

[BRIGHT SPARK]

Rooster...its a given that a Gas Safe engineer must be used .....just make sure your guy is experienced in Worcester Bosch or you may end up paying for parts you dont need.