Trying to fit a salus RT500 thermo to my Worcester 28CDi boiler. It already has a mechanical timer installed & I'm guessing that I can keep the timer permanently on & the thermo will turn on & off the boiler as temperature changes??

Any assistance on how to fit. Three wires to the timer - brown (perm live), green (switched live) & white (neutral) - does that sound right??

ANy help appreciated

Leave the timer wires alone unless you feel competent at removing it.. After the salus is fitted just run the internal timer on as constant. Switch off the electricity and isolate the boiler by removing the 3amp fuse. Drop the facia to the wiring block and you'll see the main 230v feed. To the right you will see another wiring block (ST8 ) with 4 terminals. From left to right these are NS, LS, LR, the 4th is a spare ( i think as its late!!) You need the 2nd and 3rd of these for the salus. They should be easy to identify as there should be a link wire between them. Remove it and then the LS will connect to the Live terminal on the Salus, and the LR will connect up to the Switched Live connection on the Salus.

Use heat resistant cable from the boiler to a spur, then twin & earth to the salus.

In my opinion the Salus 500 is cheap and does look like a brick. Spending just a little bit more could have got you a nice Honeywell 927

Thanks - i'll give it a go