Thermostat installation - Salus rt500rf with Boiler Ideal Classic rs500

[PaulBruk]

Hi.
I am changing to a wireless thermostat Salus rt500rf and my boiler is the Ideal Classic RS500. I have 6 wires from previous programer (2 x black, 2 x red, 2 x earth). I have tried two wiring ways, but got same result. Trial 1- put the mains live and neutral in the "L" and "N", than a loop on "L" and "COM", with the remaining Red in the NO (1 black wire with no connection). Trial 2- the mains to "L" and "N", and the other Red to COM with Black to NO.
The red light and green light turn on the correct way (green on only when calling for heat). But the boiler and the pump do Not turn on. Why?

 

[stem]

Telling us what colour wires you have doesn't really help. The selection of what colour wire was used for what, would have been at the discretion of the installer. One of the blacks may be used as a live for example.

So, what we need is a description of what terminal each wire was connected to at the previous programmer, along with details of the programmer (make / model) also, details as to where each wire is connected at the other end would be helpful.

I suspect that you may have been close with Trial 1, and that probably both black wires should be inserted into the "N" terminal. However, I would not recommend that you try this or carry on with a 'trial and error' approach before ascertaining what goes where. If you end up connecting a live to somewhere it shouldn't go, or creating a short circuit, you can quite easily cause some expensive damage to your boiler.

As a side issue, there are quite a lot of these Salus units around now and I have come across two instances of a heating system being switched on and off by the unit in a neighbouring property. So, unless you don't have close neighbours, I would suggest that you change the operating frequency as per the installation instructions, just in case your neighbour already has one, or gets one in the future.

 

[jeds]

Mains supply to L/N. LS from boiler to NO. LR from boiler to COM.

 

[stem]

Isn't that what the OP has already tried and describes as 'Trial 2"?

Trial 2- the mains to "L" and "N", and the other Red to COM with Black to NO.

 

[jeds]

If the red is Ls and the black Lr then yes but, as you rightly pointed out, we don't know where the red and black are connected at the boiler?

 

[PaulBruk]

I had tested the cables before and I knew that the cable red was L and the Black N. The system worked fine for a month connecting red + red and black + black.
The first advise from "stem" worked fine (both blacks together on the N! Thanks for the help!
I just find unusual not using the earth cable.

 

[stem]

If the red is Ls and the black Lr then yes but, as you rightly pointed out, we don't know where the red and black are connected at the boiler?

It doesn't matter if they are the other way around, they are just switch wires. When connected together the boiler runs, when they are not it doesn't.

I had tested the cables before and I knew that the cable red was L and the Black N. The system worked fine for a month connecting red + red and black + black.
The first advise from "stem" worked fine (both blacks together on the N! Thanks for the help!
I just find unusual not using the earth cable.

Glad it's sorted.