The ideal position to locate the RT300 thermostat is about 1.5m above floor level, in a location where the thermostat is accessible, reasonably lit and free from extremes of temperature and draughts. Do not mount the thermostat on an outside wall, above a radiator or in a location where it may be subjected to direct sunlight.

The electrical connections to the RT300 are made to the supplied industry standard backplate. This simplifies installation, as no connections are made to the controller itself. Connection details are shown below - no Earth connection is required for the correct and safe operation of the RT300, but a parking terminal is provided to connect an Earth wire if one is present.

After installing the backplate in a suitable location, wiring connections can be made as

shown above. The following criteria apply to the installation:

• The incoming AC mains supply should be 230V AC and fused at 5 amps.

• Optimum cable size for installation is 1.5 mm2; wiring colours should be

                  in accordance with the current requirements of the IEE Wiring Regulations.

• Cable entry should be from the rear of the backplate.

• All wiring connections should be securely made, and be firmly gripped beneath 

   the square brass washer on each terminal.

The RT300 requires two ‘AA’ alkaline batteries to function correctly. Ensure that the

batteries are inserted correctly, paying careful attention to the polarity markings on the

battery and next to the battery holders.

Do not restore the mains supply to the system until all associated items are fully installed.

NOTE: All electrical installation work should be carried out by a suitably qualified Electrician

or other competent person. If you are not sure how to install this thermostat consult either

with a qualified electrician, heating engineer or your boiler / heating system supplier for

advice on how to continue.

Do not remove or refit the RT300 onto the backplate without the mains supply to the system being isolated.