Programmable Room Thermostat Installation Question

[nath6942]

Apologies if something like this has been posted before but I have done a search and cant seem to answer my problems....

Our current boiler is a Ravenheat LS80 Combi boiler (Don't worry I am aware of what they are like....)

This is currently controlled by a siemens room thermostat with 3 wires Live, Neutral and Earth.

I have obtained a Sunvic TLX RFP rf programmable room thermostat which appears to require 4 wires Live, Output, Output and Earth....

Have I wasted my money or is there a way of installing this thermostat?

Many thanks in advance

Nathan

 

[Gunslinger]

is this the one you have ?

http://www.sunvic.co.uk/documentation/datasheets/RFP Datasheet.pdf

if so, that one only shows 3 connections, check to see if the 2 "outputs" you have listed in your original post are not infact one output just with 2 options for connection point

as for suitability/compatibility, you will need to wait for someone more knowledgeable to reply

 

[nath6942]

Gunslinger, you are correct in the type of thermostat and yes it only has 3 connections (I got carried away in my original post!)

 

[simond]

If your current stat has just a phase, neutral and earth cable (unusual) then you might be better off wiring the Sunvic receiver straight to the boiler.

It is compatible, but what an ugly out of date looking product. Hope it was cheap.

 

[Gunslinger]

but what an ugly out of date looking product. Hope it was cheap.

apart from the relatively large size of the receiver unit, that looks practically artistic compared to some of my kit

 

[D_Hailsham]

This is currently controlled by a siemens room thermostat with 3 wires Live, Neutral and Earth.

If you only have 3 wires, one of them is not being used for its correct purpose. I would guess that the green/yellow wire is not being used as an earth but as the switched live to the boiler. The blue and brown wires are probably live and neutral; but you need to check.

Which Siemens stat do you have and which wires go to which terminal?

Of course, if you have a meter you can check the voltage on the siemens stat terminals when it is on and off.

If the wires are being used incorrectly you should really replace the wire with a 3-core cable or a 3-core plus earth. The third core is usually white or black.

If that is not possible, get some red insulating tape and wrap it round the wire so future owners/ heating engineers will know it is a switched live.

The alternative to all this is to locate the Sunvic receiver next to the boiler and not use the old thermostat wires.

 

[nath6942]

Thanks everyone so far for their assistance.

Unfortunately I am not at home but after a quick search online it looks as if the thermostat is a Siemens RAA20 Room Thermostat which does not require a neutral in its installation.

Looking briefly at the wiring diagram of the boiler I can only see two wires are required for the room thermostat, I am now wondering what voltage these would be at?

I have no concerns as to the location of the receiver but wouldn't I still need the 3 wires - neutral, live and output?

Thanks again

Nathan

 

[D_Hailsham]

it looks as if the thermostat is a Siemens RAA20 Room Thermostat which does not require a neutral in its installation.

Neither does it require an earth. So why do you have three wires connected to yours. Check when you get home

Looking briefly at the wiring diagram of the boiler I can only see two wires are required for the room thermostat, I am now wondering what voltage these would be at?

There is no voltage on these terminals, it is just a connection for a switch. (volt free thermostat). According to the on-line Installation Manual page 27 Fig 48 the boiler provides a 240v supply for a timer and two terminals for voltage free thermostat.

I have obtained a Sunvic TLX RFP rf programmable room thermostat which appears to require 4 wires Live, Output, Output and Earth

Can you please check the terminals visually as, according to the online literature, the Sunvic wireless programmer you have bought does not have volt free contacts. So it cannot be used with your boiler. However they may have changed it

If it does not have volt free terminals, you will need to change it for a Honeywell CM900 series wireless stat or a Drayton one.

I have no concerns as to the location of the receiver but wouldn't I still need the 3 wires - neutral, live and output?

You will actually need four wires: Live and Neutral to supply power to the receiver (this can come from the "timer" connections in the boiler); two wires to the boiler thermostat connection from the switch terminals on the receiver.

Before you wire the receiver in permanently, you should check communication between transmitter and receiver. The programmer installation manual will explain how to do this.

 

[tonybhoy]

Your correct these are no use for Combis.

I bought two some time ago thinking they were.

They were dirt cheap as I recall,£40 + vat or something like that anyway they were returned to the supplier.