glow worm f9 fault

[gref333]

Hi. Got a problem with my combi boiler its a glow worm 24 ci.
F9 fault is flashing immediatley on start up which in the manual says system pressure switch is faulty but also the pump the runs constantly. Intermittenly sorts itself out with the pressure reading 1.5 bar then goes back to f9 with a clicking noise I think coming from pcb but not sure. A little while ago was doing this alot going from f9 with pump running then back to normal. Even got enough hot water out of to do the washing up!
Got my suspicions on the main pcb board.
Thanks. Geoff

 

[mickyg]

could be a number of things. Unfortunately F9 is also known as a "global fault" on this range, which translates as it could be anything. Might be worth sticking a new pressure sensor in, but unless you can find someone good to fault find on this model, it might be safer to call Glowworm for a repair

 

[gref333]

Thanks for responding micky. Yes f9 seems to be a fail all fault!
Ive read that changing the pressure sensor and also the thermistor can work.
I guess there the cheapest options.

 

[gref333]

Its very intermittent though. Cant see how or why either of these would leave the pump going.

 

[gazdaz36]

F9 was the global fault as this was all the fault codes went up to on older glowworm models. 3 things you could do

1- get glow worm to plug in a unit called a diacomm to diagnose the fault
2- fit a new universal display pcb with all the new fault codes to help diagnose fault
3- Take a punt on the pcb.

Thermisters and pressure sensors are usually quite robust on this boiler
Only faults with pressure sensor is usually blocked with dirt so gives a false reading on the display but if the pcb is reading 1.5bar then it wouldn't stop it firing. The other fault that the pressure sensor occasionally causes is the loss of display.

From what you say it sounds like it might be the main pcb but couldn't be certain. A new pcb will set you back about 200 quid and you can get a fixed price repair from glowworm for about 250

 

[gref333]

Thanks gaz.
Decided to replace the water pressure sensor as this was the easiest option.
Noticed there was a wire trapped between the back of the control board and the body of the boiler with a tiny bit of copper showing so taped that up, could well of been causing the problem.
Don't no which one sorted it but seems to be working fine now!
Thanks for all your help.