Worcester Greenstar 24i Heating Issue

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Location
Northamptonshire
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Worcester Greenstar 24i Condensing boiler (see pic 1) approx. 10 years old. Normally most boiler problems resolved myself, this however has me stumped.


Boiler appears to be working fine. The Honeywell controller (see pic 2) successfully activates the boiler once a day to heat up a tank of hot water (large copper cylinder ‘vented’ fed by storage tank water loft) on automatic. Alternatively activating the hot water ‘ad hoc’ via same controller also works fine. So in my mind there is no actual fault with the boiler operation.


Problem arises when activating the heating. Request heating, the value (see pic 3) opens (audible) and the light on the Honeywell controller remains on for heating operation. However the boiler fails to fire up.


This issue has happened on many previous occasions primarily as the Drayton digistat (see pic 4) is either turned down too low (no flame on display), the batteries are failing (same device) hence the wireless signal fails to reach the Drayton digistat SCR control box (see pic 2) or indeed an error has appeared on aforementioned control box (simple power off/on reset resolves). I’ve addressed all these issues yet the problem persists.


Convinced the boiler is not at fault, assumed it must be the digistat. Removed the front housing of the digistat SCR (see pic 5) and bridged the connection manually (see pic 6 – indicated by red line) with wire then operated the heating via Honeywell controller. Same thing happens, valve (pic 3) opens, Honeywell controller heating operation light remains on but the boiler fails to fire up.



At this point I’m at a loss. The signal to the boiler to fire up must be the same whether you require hot water / heating, the only difference is which value (pic 3) is open to direct the flow of heated water.

What am I missing here please.

P.S. My thanks in advance for any responses. Small gift sent in the post to the first poster who successfully resolves the issue (chocolate btw in case your on a diet).
 
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If you can hear the heating zone valve doing something then the timeclock and room stat/receiver are working ok.
Check the zone valve and see if the microswitch is being operated once the valve has opened...it sounds like you've got a weak motor and it's failing to fully open the valve.
 
Thank you so much. And you are spot on. Removed the housing from the zone value. It appears to make contact with the microswitch but does not depress it. A quick nudge with a screwdriver to fully open the value and the boiler fired up. So I'm off to get a replacement V4043H1056 Honeywell Motorized Valve. My failing here was unaware the valves had microswitches, makes perfect sense now, boiler can't be allowed to operate until confirmation that the respective value to fully opened.

@Gasguru PM me a contact address / preference of chocolate. And please don't refuse. I'm very appreciative of the time you took to help a total stranger, it is the least I can do.

Kind regards,

Poisonata
 
A little further reading it seems for ease (avoid draining the whole system down / replacing the valve assembly which doesn't appear faulty) a straight swap of the sychron motor is the best (cheapest / quickest) fix. Found one on Amazon that's suitable for a tenner. Even better :)
 
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Thanks for the offer but I'm trying to loose some lockdown lard. :)
I suggest you only buy the genuine Hansen synchron motors...eg. the Screwfix/Toolstation Drayton replacement motors in the bag (they fit).
All the knockoff valves are hopeless...I've had them last as short as a year.
 
That's good to know. Screwfix is only round the corner / got them in stock.


Lockdown (n) I work for the NHS, it's been very much business as usual. Slightly galling when everyone else seems to have had the whole summer off paid :( Maybe not a bad thing, probably struggle to motivate myself after such a long period of inactivity. Although on a more serious note a tradesman friend has been struggling to get hold of basic materials post lockdown (multifinish plaster), not ideal.

My thanks once again for your efforts, very much appreciated. Gift offer stands should you have a change of heart.

Best wishes,

Poisonata (y)
 
who’d receive chocolates from someone called poisonata? :LOL:
 
Follow up - Drayton Synch Motor purchased from Screwfix (see above for picture). Fitting took approximately 30 minutes, very easy. Only difficultly was access as it's in a tight space. Working a treat. Thank you so much @Gasguru for correct diagnosis.

Never the repair that's the issue, it's the diagnosis of the fault. Hence the follow up should anyone else encounter a similar problem.
 

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