Worcester-Bosch Greenstar 24i jr intermittent hot water

[chockychockster]

Hi all,

I have a fairly new Worcester-Bosch Greenstar 24i Junior (less than one year old) which has just started giving trouble.

When the kitchen tap is open, the boiler fires up and plenty of hot water comes out, reliably, for as long as the tap is open. But when the shower is on or the bathroom tap is open, the boiler fires for a couple of minutes, then shuts off. The green ignition light goes out, and eventually cold water comes out of the shower. Some time later it fires again, then shuts off.

There is no flashing blue light or other diagnostics.

This started with some fairly horrible noises (thunks) from inside, and I noticed recently the pressure gauge was low so I repressurised the system. Those noises have stopped but it's still not firing consistently.

Any help?

 

[bazdaman]

May not be a boiler problem if fine at kitchen tap

 

[gigz]

Take the shower head off and try that, if it works clean the shower head. Also check the green gas light stays on while the showers running, if it doesn't you need a RGI.

 

[chockychockster]

My mistake - at the kitchen tap too it shuts off after a few minutes. I hadn't had it on long enough but tonight while washing up the water went cold.

Could some air have got in (when the system pressure dropped before this fault) and be causing an airlock inside somewhere?

 

[picasso]

More likely the plate heat exchanger is blocked on the system side, do you know if the system was cleaned when your new boiler was installed?

 

[chockychockster]

Almost certainly not - the guy who installed it was very cheap and unfortunately I got what I paid for.

 

[bazdaman]

Ring worcester its still under warranty, if the system is full of crap i believe the first visit they will repair but insist you get a flush for valid warranty for subsequent visits

 

[chockychockster]

It's not under warranty unfortunately - the cowboy-type fitted it in too small a compartment and the manufacturer refused. At my wits end I sent him packing but never did the remedial work necessary to get it under warranty.

It seems common that it's either the HW temp. sensor or the secondary heat exchanger. Are they realtively easily serviceable?