Installation

G_baillie8356

I have a Worcester Greenstar 30si boiler with Siemens RAA200 hard wired controls and I want to fit the Tado hardwired thermostat it place of existing controls. My Siemens room stat wiring diagram shows 2 cables 1 into L and other cable into Y1. Where would I put these cables on the tado stat

policywonk

The RAA200 can control either 24 volts, or 240v. This link gives the layout Microsoft Word - N3002en.doc. On page 4 it presents the wiring, with

• L as LIVE
• Y1 as switched Live.

As this is a dumb thermostat, it is likely that replacing it leads to:

• Relay mode,
• the wire to L becomes COM,
• the wire to Y1 becomes NO.

Thats a simple, nothing special change.

However there is something you may not know, ie. your boiler can operate with digital controls - known as the HT BUS, which enable it to run more efficiently if controlled via that mode, not in Relay mode.

Tados support the HT BUS. However, first if you want to consider this alternative route, it is important to check how that Siemens Stat is wired into the central heating system. Check that it is wired as described in the Greenstar manual (link is here): untitled, on pages 29 and 30.

Recommend that you contact Tado via the App and ask them for instructions to implement the changes to enable the Tado wired stat to control the system using HT BUS. They will refer to a D17 mode but will give you detailed instructions.