Combi boiler hot water problem

[LB york]

I have an elderly Glowworm combi boiler. Recently and with increasing frequency the hot water has intermittently stopped working - there isn't the normal "firing up" noise as when the heater kicks in. It seems to be connected to whether the heating is on, (tho' not always) - if I turn the heating off for a while, ( even if it's only ticking over as the thermostat is low), most times it comes on again.
The plumber is flummoxed - whenever he comes it is working ! I am frustrated and fed up with not knowing if and when it will be working.
Please can anyone help - plumber now talking about replacing ? "thermostar" - not thermostat.

Thanks
LB York

 

[gas4you]

Think he means thermistor

 

[LB york]

Thanks, Dave - but will that solve the problem ???

 

[Rob]

Is this a swiftflow by any chance?

 

[LB york]

yes it is - and pretty elderly but otherwise working fine.

 

[Rob]

Most intermittent faults on these are down to the PCB. Went to one just this week, give the boiler a knock on the front but low down, next time it wont fire for hot water.

Not a bad boiler TBH

 

[LB york]

Thanks for the tip Rob - sorry to be ignorant but what's a PCB ???

 

[sambotc]

Printed circuit board

HTGH Sam

 

[LB york]

Thanks ! I tried the thumping technique, Rob and it worked ! Is there a more permanent / technical solution that a plumber could undertake or is that it ?

 

[Rob]

Thanks ! I tried the thumping technique, Rob and it worked ! Is there a more permanent / technical solution that a plumber could undertake or is that it ?

Yes, replace the circuit board. There are 3 (i think) on this boiler so may require examination, i have had to replace two at once before.

Whilst the actual swap of the board is fairly easy there are pots (adjusters) on the board which require setting up to the correct gas pressures which is crucial. Corgi territory, unfortunatley.

Rob

 

[LB york]

Thanks, Rob - now to see if I can convince the plumber - who's at the same stage of life as the boiler !

 

[Rob]

You have to give him a wack to get him working too!

 

[LB york]

Don't tempt me !