Combi boiler problems: What are your opinions please?

[underwurlde]

Combi-boiler: Glow Worm UltraCom 30cxi
Installed: 2007
Serviced: From the log book, never.
Issues found: Stuck diverter valve:

Moved into my new home November last year. Immediately noticed problems with hot water in so much as the radiators would warm up too.
'Solved' this somewhat by removing actuator from diverter valve & moving the valve shaft in & out with some pliers- it was ceased presumably with lime-scale.

Problems abound with room heating though:
The boiler just 'ticks over' (only ever on 'full blast' when DHW demanded) and seems to have a mind of its own!
The radiators heat seem to cycle going from very hot to luke-warm over a 10 hour-ish period. If we are cold, setting the thermostat up does NOT kick the boiler into being HEAT HOUSE, conversely if too hot, turning the thermostat down does NOT then turn the radiators off.

Room stat
Thermosat (Drayton Combi-stat RTS8) in front room.
I initially thought this to be duff (dirty contacts) so replaced it, like for like.
Made no difference.
It appears that regardless of the setting, it's setting is ignored by the boiler.

Programmer ignored
The on-board programmer provided by this combi-boiler is also ignored. Does not matter if in an ON or an OFF period, boiler just ticks-over as described above.

Also, turning the heating only off (hence DHW on) via the 'mode' button does NOT turn the central heating off. Only when the mode is set to OFF (DHW and heating off) does the boiler then do as it's bl00dy well told.

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Weird, weird, WEIRD!

My thoughts are:
maybe it is in a strange 'test' or 'learn' mode?
The control board is f-ed.
The system needs a good old fashioned clean.

Any insights would be GREATLY appreciated!

Andy

 

[ServiceNumpty]

Isn't there a link on these that has to be removed if the roomstat is connected into the low voltage side, or am I talking out of my arris.

 

[underwurlde]

Ahh. really! Could well have been like this for the last 8 years!

Where can I find said link please?!?!

Apparently this boiler was installed by the previous owners dad who was a 'Master builder' and 'Corgi registered'. (My Arris)

NOT that my solicitor could find ANY record of this installation having been listed on the Corgi website OR a certificate of installation. This caused problems with the house purchase, to which I insisted they take out indemnity insurance on my behalf to cover incorrect boiler installation problems in the future.

Should've known better.

Andy

 

[gazdaz36]

Sounds like a problem with your diverter still to me. Your boiler might be on dhw pre heat that is struggling to reach temp as your losing the heat from the boiler into your radiators

 

[underwurlde]

hmmm. Can pre-heating be turned off? Sounds like a waste of good gas to me. No doubt there is a good reason for it though.

FWIW I am reverse engineering the control board to gain a schematic. 95% done so far and 100% copied the PCB design.

Thanks for all the replies.

Andy