Siemens RDH10RF/KIT to Remeha Avanta (Volts free?)

[Dan_nearly_the_man]

I've done tons of searching and I think I know what I'm supposed to do, but I've also come across some contradictions.

So my boiler/thermostat issue is as follows. I have a Remeha Avanta with a Siemens RAA20 room thermostat.

It connects to the boiler via two wires like below, and the connection diagram is as below:

Pic_1

• Dan_nearly_the_man
• 23 Jun 2015

I have purchased a Siemens RDH10RF/KIT wireless thermostat that’s receiver looks like this:

Pic_2

• Dan_nearly_the_man
• 23 Jun 2015

My boiler has these pages in the manual referencing its electrics and connecting external controls:

Pic_3

• Dan_nearly_the_man
• 23 Jun 2015

Pic_4

• Dan_nearly_the_man
• 23 Jun 2015

So. I think I’m supposed to wire as follows, with some new flex to the boiler's terminal block x6 (which I assume is just mains power) to give power to the receiver?

Pic_5

• Dan_nearly_the_man
• 23 Jun 2015

So before I go ahead and potentially blow everything up, I just wanted someone to say either: "Yes! All good!" or "No! Everything will explode". If the latter an alternative method would be appreciated.

PS Is this cable ok to use for the new mains cable:
http://www.wickes.co.uk/Wickes-2-Core-Flex-Cable-Round-0-75mm-x-7-5m-White/p/710476#

I'm normally fine with this sort of stuff, but the fact its my boiler increases my self-doubt.

Cheers

 

[D_Hailsham]

Which boiler terminals is the current stat connected to?

 

[Dan_nearly_the_man]

I've not yet had the fascia off the boiler, plan to do it tonight, but I'm expecting them to be connected to 7 and 8 on the X9, I'm also assuming that the 'existing link' has already been removed, to fit the first stat. If that affects how it may be done , I can post that info tonight.

 

[D_Hailsham]

Never assume!

Apart from the thermostat, do you have a timer/programmer? If so it should be connected to X2

I'll wait for you to check.

 

[Dan_nearly_the_man]

I'll check that at the same time. Its just a 24hour manual timer- fixed in to the front of the unit.

 

[D_Hailsham]

Just the standard Remeha timer, which will plug into X2.

You should really use heat resistant cable as it goes inside the boiler. A 4-core (+ earth) would be ideal.

 

[Dan_nearly_the_man]

Hi thanks for your help with this. So here is the wiring inside the boiler:

Stat

• Dan_nearly_the_man
• 23 Jun 2015

The current stat does indeed connect to 7 and 8 on X9. X2 is occupied by the timer as you said.

So am I right in thinking that 7 goes to L1, and 8 goes to LX? But where do I get the mains power? Am I ok to feed it from main supply for the boiler (which is the white block connector X6 in the picture)? Or do I do something with the fused switch spur? Forgive my ignorance in these matters.

If the mains supply to the receiver doesn't even interact with the boiler in any way, can I just throw a 3A plug on it? There is a double socket co-located that I assume the spur is ran off. If I'm not creating a dangerous situation by doing this, it seems the simplest solution.

 

[D_Hailsham]

The current stat does indeed connect to 7 and 8 on X9. X2 is occupied by the timer.

The existing stat wires go to L1 and LX - it doesn't matter which way round.

Power to the receiver can be taken from X6.

 

[Dan_nearly_the_man]

Excellent, thanks very much for your help. One final question; (the silly one is the one that is never asked and all that) why 4-core (+earth)? Would that be to run all four connections using the same cable?

 

[D_Hailsham]

Excellent, thanks very much for your help. One final question; (the silly one is the one that is never asked and all that) why 4-core (+earth)? Would that be to run all four connections using the same cable?

Yes.

The receiver will need to be mounted near the boiler. If the existing stat cable can be diverted, there's no reason why it can't be used again. You would then only need a 2-core to power the receiver.