greenstar 24i junior hotwater problem

[stevejordan]

hi hope someone will help
problem as follows -
turn on hotwater outlet , get loads of hotwater , after 5 mins runs cold , then hot again , this then just repeats .
this is a big problem when showering or running a bath
boiler about 4-5 years old condensing type
regards steve

 

[BLOD]

Sounds like a blocked plate heat exchanger

 

[Billy Bob Bob]

or sticking ap switch or thermister and yes the greenstar amazingly does have a ap switch

 

[stevejordan]

or sticking ap switch or thermister and yes the greenstar amazingly does have a ap switch

"ap" switch ????

 

[Billy Bob Bob]

air pressure switch

 

[stevejordan]

thank you , but would the aps affect the heating or not , as we dont have a problem with this

steve

 

[Billy Bob Bob]

not always sometimes affects hotwater as the boiler goes to a higher rate

 

[mikegas]

Could it not be that the low burner setting is too low making the boiler go out instead of modulating?