Worcester Greenstar 24i junior - No Central heating.

[stickle]

Advice please re: Worcester Greenstar 24i junior about 4 years old.
Problem: No Central heating.

Current status:

System re-pressurized from '0' to '1.5' bar after approx. 3 months not used.
Digital Timer on 'override' (calling for heat)
Hot water was & is OK
All radiators get hot in maintenance mode (Spanner symbol)
'Reset' or switching on/off does not fix.
No unusual noises.
'Blue light' steady.
Diverter valve ?
Any advice most appreciated.

Reasonably competent OAP tech retired. (& poor!)

 

[JohnD]

what temp is the room stat set to?

what temp is the room?

 

[gigz]

My bet, batteries in room stat.

 

[stickle]

Thank you both for your quick feedback.

New batteries fitted 1 week ago.
Room temp was 19 C
RF Stat is set to 30 C
I can see 'receiver' working aprox. every 5 mins.
Time switch is set to 'Over-ride' (red light on) so this would ignore any stat fault anyway. I will go in to boiler and link out the timer to be sure.

 

[JohnD]

ah, a wireless room stat.

Does the receiver indicate on/off when you alter the setting on the sensor?

 

[stickle]

ah, a wireless room stat.

Does the receiver indicate on/off when you alter the setting on the sensor?

Yes it does.
Shows red light 'on' - call for heat - when sensor set to 30 C
shows no light for 'off' when sensor set to 10 C
(room temp is 19 C)

 

[JohnD]

ok, so at least it isn't the transmitter or a "bad wireless connection" problem

I take it you have no hot-water cylinder?

 

[stickle]

ok, so at least it isn't the transmitter or a "bad wireless connection" problem

I take it you have no hot-water cylinder?

No. That was removed along with the tank in the loft when the combi was installed.
I don't know what to try next.

 

[mcmoby69]

knob in winter position? broken maybe?

still too early for CH even in Yorkshire, thought you guys were made of sterner stuff! The southern jessies, yes I could understand.

 

[stickle]

"mcmoby69" - knob in winter position? broken maybe?

I am a Scoucer Sir! My knob is not in winter position.

I agree with your comment however. I am trying to get my C.H. working for a Yorkshire winter. Stat & timer have been by-passed. Still won't go. I am running the C.H. in diagnostic mode to get a 15 min. burst of heat.
There must be someone out there that has had the same problem I am having now.

 

[Phill Peck]

When you sal bypassed, you've linked internally at the boiler?

Is it a worcester plug in receiver you've got or an external wired in?.

 

[stickle]

gasservice1985W - When you said bypassed, you've linked internally at the boiler?

I have linked the boiler 'Ls' & 'Lr' connections in the boiler to bypass the timer.

 

[Phill Peck]

If it's an internal receiver though it may ned to be unplugged from the pcb

Not sure how these are connected on this boiler think there is a ribbon connector behind the receiver

 

[andycarmi]

Hi Did you manage to get to the bottom of this problem? my boiler a 28i junior is doing the very same thing?

Thanks

Andy

 

[stickle]

Hi Did you manage to get to the bottom of this problem? my boiler a 28i junior is doing the very same thing?

Thanks

Andy

Hi Andy - Yes, The fault was/is with the 'Drayton Digistat SCR' receiver not operating its on-board relay (should be about 24v but found to be less than 6v). I read on the web that this is a common fault that can be fixed by replacing the 0.68 uF 275v ac rated capacitor that supplies it. I have sent for a replacement (from China). [Google - Drayton Digistat SCR & you should find this info]. In the mean time I am running the heating via a cheap mechanical room stat. and a timer that sends a 'live' to 'L return' on the boiler control card. I can pick up this connection at the Drayton connector block when the wireless system is removed so there is no need to open up the boiler. The temporary system works well so even if the cap. doesn't do the job I'm quite happy with this 'primitive' arrangement. - Good luck with your 28i. & beware Live wires !!

ps. press & hold in the 'maintenance button' [on the front of the boiler] for at least 12 secs. - button should light up orange - This should give you a FULL blast of heat to the radiators for about 15 mins. & then shut its self down again . Assuming your water pressure is above 1 BAR etc.
************
UPDATE 6 NOV.
Turned out the capacitor was ok. I have drawn out the circuit and layout of the Digistat (This took some time!). From this info I found out that the voltage regulator transistor had gone short circuit colector/emitter. There is no way I can replace this tiny surface-mounted part so I have disabled it and fitted a 78L05 (3 leg 5V voltage regulator) and all is now well in time for winter. See the pics. [click on 'stickle' & look in Album] for details of what fixed mine - IF YOU ARE OK WITH ELECTRONICS!! - At your own risk.