Vaillant/Glow-worm 30cxi F13 fault & now F12 fault with

[PROSINGER]

Having been away for 2 years we came back to a 30cxi boiler that displayed an F13 fault but would still work intermitantly. I just replaced the main board fired it up and now have the fan constantly active, the water pressure indicator jumping erratically from 0.4 up to 1.8 and an F12 fault. I checked all connections and seem ok. It's getting to be an expensive boiler and would really appreciate any help with suggestions as to where to look next. Please no advice on replacing it with another Glow-worm.
Thanks in anticipation

 

[naanbread]

Having been away for 2 years we came back to a 30cxi boiler that displayed an F14 fault but would still work intermitantly. I just replaced the main board fired it up and now have the fan constantly active, the water pressure indicator jumping erratically from 0.4 up to 1.8 and an F12 fault. I checked all connections and seem ok. It's getting to be an expensive boiler and would really appreciate any help with suggestions as to where to look next. Please no advice on replacing it with another Glow-worm.
Thanks in anticipation

Hi There,

F14 is caused when the thermistor on the flow pipe is above 95 degrees. This was probably not a board issue in the first place. Check your resistance on the thermistor at room temperature, you should have between 10k and 12k. Its an NTC so the warmer it is the less the resistance. It is sometimes specific to hot water which is usually an issue with the plate to plate heatexchanger being restricted causing the temperature on the flow to rise too high. a good test to prove this is to measure the temperature on the flow and return in the demand. You would notice the flow getting hot but the return staying cold/more than 30 degrees difference.

In relation to the F12 fault. This is a communication error between the PCB's. I would suggest taking off the low voltage components as they can cause an interuption on the signal between the boards. These are J1, J4 and J2 on the main pcb. It will then show you another fault. If it shows a fault other than F12 then one of the low voltage components is causing the issue. Its a process of elimination test which means you put one plug on at a time and see which is causing the issue.
If it goes back to F12 when you take these plugs off i would suggest checking the harness to the display which is J13 (5 red wires). If thats ok its most likely an issue with the display board. Sometimes when these boards are changed they do not recognise one another so it can cause issues like this.

The GW technical team are helpful with these issues.

I hope this helps

NB

 

[PROSINGER]

Having been away for 2 years we came back to a 30cxi boiler that displayed an F14 fault but would still work intermitantly. I just replaced the main board fired it up and now have the fan constantly active, the water pressure indicator jumping erratically from 0.4 up to 1.8 and an F12 fault. I checked all connections and seem ok. It's getting to be an expensive boiler and would really appreciate any help with suggestions as to where to look next. Please no advice on replacing it with another Glow-worm.
Thanks in anticipation

Hi There,

F14 is caused when the thermistor on the flow pipe is above 95 degrees. This was probably not a board issue in the first place. Check your resistance on the thermistor at room temperature, you should have between 10k and 12k. Its an NTC so the warmer it is the less the resistance. It is sometimes specific to hot water which is usually an issue with the plate to plate heatexchanger being restricted causing the temperature on the flow to rise too high. a good test to prove this is to measure the temperature on the flow and return in the demand. You would notice the flow getting hot but the return staying cold/more than 30 degrees difference.

In relation to the F12 fault. This is a communication error between the PCB's. I would suggest taking off the low voltage components as they can cause an interuption on the signal between the boards. These are J1, J4 and J2 on the main pcb. It will then show you another fault. If it shows a fault other than F12 then one of the low voltage components is causing the issue. Its a process of elimination test which means you put one plug on at a time and see which is causing the issue.
If it goes back to F12 when you take these plugs off i would suggest checking the harness to the display which is J13 (5 red wires). If thats ok its most likely an issue with the display board. Sometimes when these boards are changed they do not recognise one another so it can cause issues like this.

The GW technical team are helpful with these issues.

I hope this helps

NB

Thanks naanbread for your reply but like an idiot I meant F13 fault and not F14. I can say that the thermistor on the flow pipe seems ok reading around 10k, any more help appreciated.
Brian

 

[picasso]

recheck the connections you have done/undone, its very easy to bend one of the pins and not realise.

 

[PROSINGER]

recheck the connections you have done/undone, its very easy to bend one of the pins and not realise.

Thanks picasso, I will re-check them, it's an intermitant fault, it's been working fine for a couple of days but if I were to turn the hot tap on it would probably cut out.

Brian

 

[naanbread]

Having been away for 2 years we came back to a 30cxi boiler that displayed an F14 fault but would still work intermitantly. I just replaced the main board fired it up and now have the fan constantly active, the water pressure indicator jumping erratically from 0.4 up to 1.8 and an F12 fault. I checked all connections and seem ok. It's getting to be an expensive boiler and would really appreciate any help with suggestions as to where to look next. Please no advice on replacing it with another Glow-worm.
Thanks in anticipation

Hi There,

F14 is caused when the thermistor on the flow pipe is above 95 degrees. This was probably not a board issue in the first place. Check your resistance on the thermistor at room temperature, you should have between 10k and 12k. Its an NTC so the warmer it is the less the resistance. It is sometimes specific to hot water which is usually an issue with the plate to plate heatexchanger being restricted causing the temperature on the flow to rise too high. a good test to prove this is to measure the temperature on the flow and return in the demand. You would notice the flow getting hot but the return staying cold/more than 30 degrees difference.

In relation to the F12 fault. This is a communication error between the PCB's. I would suggest taking off the low voltage components as they can cause an interuption on the signal between the boards. These are J1, J4 and J2 on the main pcb. It will then show you another fault. If it shows a fault other than F12 then one of the low voltage components is causing the issue. Its a process of elimination test which means you put one plug on at a time and see which is causing the issue.
If it goes back to F12 when you take these plugs off i would suggest checking the harness to the display which is J13 (5 red wires). If thats ok its most likely an issue with the display board. Sometimes when these boards are changed they do not recognise one another so it can cause issues like this.

The GW technical team are helpful with these issues.

I hope this helps

NB

Thanks naanbread for your reply but like an idiot I meant F13 fault and not F14. I can say that the thermistor on the flow pipe seems ok reading around 10k, any more help appreciated.
Brian

Hi Mate,

Not to wory, at least you know now what causes an F14

if you have F13, it is the PCB telling you that one of its connections is missing. The usual cause of this is the earth on the electrode. This is located on the burner door. If the seal around the electrode fails/passes, heat escapes and it burns the earth. Check that your earth isnt burnt/discoloured. If it it, replace it and check the seal. It may be worth looking into replacing the burner seal too if this is the case.

Hope this helps

NB