Wiring help for Centaurstat 7

[Paul G]

I wish to replace a Satchwell TLM2253 with a Horstmann Centaurstat 7 for a conventional CH system (fully pumped with programmer and 3-port valve). The existing Satchwell stat (2253) has three wires cabled up to terminals #1, 3 and #4. Reading its installation manual, #1 and #4 are Neutral while Live is #3. I gather #4 is for a shunt accelerator heater because the 2253 uses a bi-metallic strip mechanism ?

How do these map to the Centaurstat terminal block ? Am I correct in thinking I need only cable up to #1 (Live) and #2 (Neutral) ?

Thanks Paul

[John Rumm]

Your existing stat probably has live, switched live, and neutral. The neutral is indeed to allow the shunt resistor to be powered.

The new stat will not require a neutral at all (you can park it on terminal 4 of the centaurstat). It just needs live and the switched live connected to terminals 1 and 2.

[John]

The Centaurstat doesn't need a neutral - tape it up. It needs the live feed and the switched wire that goes to the boiler. I think your reading of the Satchwell wiring is a bit incorrect.