Glow-worm compact 100e hot water problem - please help!

[Shimlasun]

Would be grateful for any advice. My Glow worm combi boiler (16-18 yr old) is heating radiators fine, but a few weeks ago starting producing only luke warm water. This morning after the central heating was off all night, only cold water came out the hot water. This evening (the central heating had been on a few hours), some hot water came out followed a few minutes later by just luke warm water. Is this most likely the heat exchanger or diverter valve or neither? Not sure if relevant but since the summer the boiler has leaked intermittently which I was told by someone in the know, that it was likely the o-rings. Could this be a clue it’s the heat exchanger being the current problem? Thanks in advance for your advice - Katherine - total novice diyer

 

[ianmcd]

Most likely the diverter valve needing a service kit, and good chance this is where the water was leaking from and sounds like it has got into the actuator motor

 

[GuessMan]

If the central heating flow pipe gets hot when running the hot water Ian is right if not you need a RGI as it is likely the pcb.

You CANNOT change this yourself as various gas valve control settings need to be set up.

Best advice is find someone who takes credit cards and fit a new one with a long warranty. Group Service engineers hate this boiler and for good reason; they know how it works.

 

[Shimlasun]

Thanks so much both - I’ve checked when I run the hot the central heating flow pipe doesn’t get hot.
Apart from the pcb, what do you think about it being the plate heat exchanger or the thermister. I’ve had a couple of RGIs around - one thinks the plate heat exchanger as water luke warm so simply not heating it as well. The other said would get water temp varying hot to cold more intermittently minute to minute if it was the heat exchanger, and therefore thinks the thermister is the more likely problem.

What do you think?
Not sure who has the right diagnosis and therefore who to go with??
Today when I ran the hot tap, the central heating having been off, it started off cool for several minutes before gradually heating up to relatively hot. Also I’ve noticed if I run the Bath very very slowly instead of getting a luke warm bath as I had been, it’s pretty hot...
Does that help narrow it down?
Thanks in advance.

 

[ianmcd]

still sounds like the diverter valve but keep asking untill you get the answer that you want and when that doesnt work come back and get the diverter valve looked at

 

[GuessMan]

If I'm right (I'm not always), there will be a scorch mark on the middle bottom of the PCB when the cover is removed.

 

[ollski]

Gas pressure will be stubbornly stuck at 4.5mb and the pcb will sort it as above.