worcester greenstar 28i hot water issues

[freezy121]

Hey guys,

Having issues with a worcester 28i junior combi. Heating is fine but when the hot water is in use it stays hot for around 30 seconds to a minute than runs cold. The boiler does not lock out. If the taps is then closed and re opens the same process happens. Hot for a short while than cold again.

I have thought it could be down to two things either the pump or the plated heat exchanger.
Could anyone offer any advice as it would be greatly appreciated?

 

[petit_pablo]

Does it come hot again if you leave the tap running?

 

[freezy121]

No it doesn't. If i turn the tap off then back on it does.

 

[chrispalmer1977]

See my comment on your other post...

 

[Gasguru]

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moderator's note:
This is a reply to a post that has been removed
++

Replacing the parts you have is strictly non diy...see the forum rules on work within the combustion chamber.
In addition you've posted this under a completely different boiler model...the iJuniors are not the same as the Greenstar Juniors.

This is a very common fault that us in the trade have known about for the last 10 years...takes us a minute to diagnose
The pcb often fails to run the fan at high speed causing the burner flames to lick around the side melting the T piece and sometimes the APS.