Drayton RF SCR Questions

[Steve1138]

Hi all

I was hoping someone might be able to help.

I have a Drayton +3RF wireless thermostat that was installed by the previous owners of my flat.

Since moving in we have had problems with the SCR activating the heating whenever it likes (ie when the control is not calling for heat)

We have removed the batteries from the thermostat to rule that out and the heating still comes on and off throughout the day.

Drayton have confirmed that no other controller (a neighbors for example) could be causing the SCR to activate as they are designed to only work with the controller they are commissioned to. They have sent me out a replacement SCR as a goodwill gesture but it is still happening and Drayton have no idea what is going on.

I am thinking that it is something to do with how the previous owners wired the SCR to the boiler going by some of their other "DIY" attempts we have found around the flat.

We have a Glowworm 30CX boiler, is anyone with any experience of connecting a Drayton wireless SCR able to confirm how it should be connected (ie what type of wire should be used and whcih points in the SCR should be connected)?

Thanks

Steve

 

[D_Hailsham]

Can you list the current connections between SCR and boiler? e g SCR terminal 1 to Boiler terminal L. Also say if there are any links between terminals.

 

[Steve1138]

Thanks for the reply

There is a picture of the back plate of my SCR in this thread:

//www.diynot.com/forums/plumbing/drayton-digistat-3rf-glowworm-flexicom-30cx-problem.295640/

I have not opened up the electrical cartridge of my boiler yet so I am not sure at the moment which terminals are connected in the boiler itself.

The SCR plate definitely looks wrong to me though, surely there is not supposed to be a link between the L and 1? I have the basic wiring diagram that comes with the SCR and it seems to show that 4 core cable should be used to connect to the boiler and not 3 core?

 

[D_Hailsham]

There is a picture of the back plate of my SCR in this thread:

//www.diynot.com/forums/plumbing/drayton-digistat-3rf-glowworm-flexicom-30cx-problem.295640/

Why did you start a new topic?

The SCR plate definitely looks wrong to me though, surely there is not supposed to be a link between the L and 1?

That all depends on how it is connected at the boiler end!

I have the basic wiring diagram that comes with the SCR and it seems to show that 4 core cable should be used to connect to the boiler and not 3 core?

Again, that depends on how it is connected at the boiler end. One method required three wires, the other four wires. In either case the earth wire should not be used to carry voltage, as it is in the picture. You will need either three core or 4-core heat resistant cable (plus earth), depending on how it is wired at the boiler end.

Time to get the cover off and see which terminals the cable is connected to.

 

[Steve1138]

To be honest I forgot I had an older thread until you asked for how it was wired, I remembered I had taken pictured previously and found the thread.

I will take the electrical cartridge out of the boiler tonight then to see how it is connected at that end and will let you know.

Thanks

 

[Steve1138]

I'm having a bit of trouble removing the electrical cartridge from the boiler.

Is there a knack to getting these out??

 

[D_Hailsham]

I'm having a bit of trouble removing the electrical cartridge from the boiler.

Is there a knack to getting these out??

Have you undone the two screw which secure the cartridge in place?

There is also a single screw holding the cover on the cartridge.

 

[Steve1138]

I'm having a bit of trouble removing the electrical cartridge from the boiler.

Is there a knack to getting these out??

Have you undone the two screw which secure the cartridge in place?

There is also a single screw holding the cover on the cartridge.

There are 2 white plastic "pins" on the underside of the boiler, on either side of the electrical cartridges hole, no screws though.

I did have the boiler cover off and pulled out these 2 pins which released the block that I believe holds the cartridge inside but I couldn't open this any further.

I was under the impression that it should be possible to just pull the cartridge out from the bottom of the boiler without taking the cover off?

 

[Steve1138]

Here is a picture of what I can see under the boiler where the electrical cartridge is:

Untitled

• Steve1138
• 29 Mar 2012
• 1

[/img]

 

[D_Hailsham]

The screws are where the arrows point!

Untitled

• D_Hailsham
• 30 Mar 2012
• 1

 

[Steve1138]

They are holes, not screws.

 

[D_Hailsham]

They are holes, not screws.

Then the screws are missing!

Can you remove the cover from the plug? That would allow you to see how the two cables are wired to the plug, which would be good enough to determine what is wrong.

 

[Steve1138]

Managed to get the cartridge out finally

SCR:

Untitled

• Steve1138
• 29 Mar 2012
• 1

Boiler electrical cartridge (The top cable is coming from the mains, the bottom cable is the one connected to the SCR):

Untitled

• Steve1138
• 31 Mar 2012
• 1

Doesn't look right to me but I'm no expert by any stretch!

 

[D_Hailsham]

The wiring is correct.

The brown and blue wires provide power to the SCR from the N and L terminals of the boiler. The link between L and 1 is required so the SCR can feed 240Vac back to boiler terminal R via terminal 3, which is the switched live.

Sounds like a fault in the SCR. The switch which connects 1 to 3 when the SCR is turned on is obviously closing at random times. If you have a multimeter you can check the SCR.

 

[Steve1138]

Hmm, that's thrown a spanner in the works!

This is the second SCR we have had and both have done the same thing.

Drayton have no idea why this is happening either