Just moved into new house with Drayton RF SCR... errrm!

[lardbros]

Am I okay to take the front off the boiler? Not illegal or anything is it?

The front cover is only cosmetic, so I would go ahead and remove it.

I'll take some photos of both ends of the cable.

The pics must show the terminals each wire is connected to.

Here is a photo of the RF unit, and the wiring inside...

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• lardbros
• 23 Mar 2012
• 1

Now, I couldn't get the boiler front panel off unfortunately. Is this photo enough to go on?

I understand your comments, but clearly a professional has been called in to install this boiler at some point, but also got it wrong (no offence to the pro's in here)... I do have an understanding of electrics, just never touched a boiler thermostat before, hence why I'm asking for as much info as possible, before I decide what to do.

If it's too much for me, I'll get someone in... but I have just added a plug socket to my ring-circuit downstairs, so know what I'm doing regarding that kind of thing.

I won't say I haven't been warned though... and thanks for the concern

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• lardbros
• 23 Mar 2012
• 1

 

[D_Hailsham]

Here is a photo of the RF unit, and the wiring inside...

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• lardbros
• 23 Mar 2012
• 1

Now, I couldn't get the boiler front panel off unfortunately. Is this photo enough to go on?

I need to know which terminals on the boiler the wires are connected to. I can make a guess, but I would rather be certain.

Which model Worcester boiler do you have? If it's a recent or current model, this is how it should be wired:

Receiver - Boiler
L ---------- L
N --------- N
1 --- ----- Ls
3 --------- Lr

At the moment the receiver is getting power from the Ls terminal, which is alive only when the timer says so. The receiver needs a permanent supply to L and N.

 

[lardbros]

Okay... thanks very much for your responses.

I'll have a look at the exact boiler model and get back to you tonight. I had a quick look yesterday but couldn't see the model number... and don't have any instructions on it anywhere (thanks to the previous owner).

Also, I can't seem to remove the front panel, so will check the model number somehow, find the manual online and try and get the cover off... hopefully this will help matters a lot.

All I know, age-wise, is that the boiler was installed in 2007 or 2008-ish. So it's not ancient.

 

[lardbros]

Okay... here goes.

The boiler is a Worcester Greenstar 28i Junior... and I had a look at the wiring inside, it is as follows (it was too confined to take a decent photo, so filmed it and am relaying what I see.)

RED - LR (from the SCR)
BROWN - Ls (from the SCR)
BLUE - Ns (from the SCR)

TURQUOISE? - N (from Mains, I assume)
BROWN - L (from Mains, I assume)



Any help is much appreciated!


Thanks!

Tim

 

[lardbros]

After reading my description, I thought I should take a picture just to illustrate it better.


Here it is:

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• lardbros
• 23 Mar 2012
• 1

 

[D_Hailsham]

You need to wire as follows:

Boiler - Colour - Relay

L ------ Brown ---- L
N ------ Blue ------ N
Ls ----- Red ------- 1
Lr ----- Black ----- 3

Ns is not used.

 

[lardbros]

Thank for that... all done, but all is not well still.

I've wired as you said... also reset the RF Thermostat, and the SCR... but now the over-ride button doesn't appear to do anything (not sure it did before-hand actually), and the boiler won't ignore the ON signal if the timer switches are set to OFF

Is it possible the timer could have been wired in badly? Or does it not need any wiring?

 

[D_Hailsham]

but now the over-ride button doesn't appear to do anything

The override button is there so you can turn the boiler on and off if a fault occurs. When the fault is rectified it will automatically revert to normal working. You can simulate a fault by taking the batteries out of the control unit.

the boiler still won't ignore the ON signal if the timer switches are set to OFF.

Just to clarify what is wrong, is this correct?

1. If the timer is OFF, the boiler will still come ON if you turn the thermostat up and stops when you turn the thermostat down.

If so, this means the thermostat is completely ignoring the timer. The wiring of the thermostat is correct, so either the timer is wired incorrectly or it is incompatible with your thermostat.

Might be a good idea to contact WB

 

[lardbros]

Ah, okay... so the over-ride works if I take the batteries out... just good to see that something works properly.

You are correct with your description of what is going wrong...


So, the timer unit is a Worcester-Bosch 'MT 10'


I've flicked through the booklet, and it seems it doesn't have any wiring, except a small connector, as I had anticipated, so doubt it could possibly be wired incorrectly... the timer ticks as normal, but yes, it's the same as ever, the thermostat is ignoring the timer.

Hmmmm, so contacting Worcester directly eh?


I can't thank you enough for helping so much... if there's any other things I can check, please shout and I'll have a look.


Thanks again!!!

 

[lardbros]

Just checked on their website... the MT10 is compatible with the boiler I have, need to to find out if the Drayton SCR is too. So maybe I have to call someone out afterall


Will have a go at Worcester and see what they say.

Thanks again

 

[lardbros]

Just a bit of further info on this...

my boiler appears to not fire up at all when in 'timed' mode. Even if the thermostat is telling it to, the SCR turns on the green light, but the boiler won't fire...

hmmmmm... any ideas? I guess this is why the original installer must have wired it all wonky.


Just out of interest, how many pins are there MEANT to be on the back of the MT10 little plug thing?

There are 7 holes for the thing to fit into in the circuit-board, but it LOOKS as if a pin has been snapped off the timer unit in order to fit it in the 7 holes!

Thanks again!

 

[D_Hailsham]

My boiler appears to not fire up at all when in 'timed' mode. Even if the thermostat is telling it to, the SCR turns on the green light, but the boiler won't fire

Do you have a multimeter (and know how to use it )? If so, remove the SCR from the back plate and measure the voltage between 1 and N. It should read 240Vac when the timer is ON or set to continuous. If you don't get 240V, there could be a fault in the timer. Check the voltage between 1 and N for various settings of the timer.

If you get the correct voltage between 1 and N, the fault could be in the SCR. That's harder to check, but you can do it by measuring the voltage between N and Lr on the boiler, with the SCR refitted to the backplate. You should get 240V when the SCR green light is ON.

There are 7 holes for the thing to fit into in the circuit-board, but it LOOKS as if a pin has been snapped off the timer unit in order to fit it in the 7 holes!

That's OK. If the pin wasn't missing you wouldn't be able to plug the timer in as the 8th hole on the PCB socket is filled in. It makes sure the plug can only be put in one way round.

 

[lardbros]

Excellent! Thanks very much for the extensive help you're handing out!

Just as a note on the small plug for the timer... hypothetically... what would happen if the small plug was put in the wrong way round? What I'm getting at is, what if the original person installing it removed the pin from the wrong corner, and it has actually been installed up-side down? (Does that make sense?)

I do have a multimeter... ha, and do know how to use it.

I'll give that a whirl, and see what I get... will be back in due course.


Oh... and I got in touch with Worcester-Bosch. The guy asked if I had the MT10 timer wired in? Does he mean the small 8 pin socket? Or is it meant to be 'hard-wired' another way? It clearly hasn't been hard-wired anywhere, nor is there any opening or way into the timer unit that I can see...

 

[D_Hailsham]

I'm getting at is, what if the original person installing it removed the pin from the wrong corner, and it has actually been installed up-side down?

The pin would have been removed in the factory where the timer was assembled. Any error would have been picked up when it was tested and by Quality Control.

The guy asked if I had the MT10 timer wired in? Does he mean the small 8 pin socket? Or is it meant to be 'hard-wired' another way?

He meant plugged in. The socket supplies power to the timer and received the ON signal from it.

 

[Jezclayton]

I do have a multimeter... ha, and do know how to use it.

If that's the case, is there any reason you hadn't thought to put the multimeter to use earlier?