Thermostat connections

webby_58 · Apr 21, 2012

Hi guys

I am replacing an old Honeywell stat with a Salus RT200. The old stat a live and switched live ( no earth ).

New stat has connections L / SL / N earth connection for park only. I have identified the L & SL from the supply ( twin and earth flex ). The cpc has been cut back at both ends of cable.

I have tried to connect L & SL in the new stat and nothing happens , the boiler won't fire and the stat does not respond.

Can anyone advise.......?

Cheers guys...

jeremy · Apr 21, 2012

I don't know the stats in question, but it sounds like you need a neutral to make it work, but as important, you must have a cpc with the cable run. Run a new 3c +E

J&M Electrical · Apr 21, 2012

Either get it rewired in 3C and earth, or get a new LV stat that works with just 2 cores.

webby_58 · Apr 21, 2012

Confused.com as the boiler does not require a neutral connection ......?

J&M Electrical · Apr 21, 2012

The boiler doesnt require a neutral? i think you'll find the boiler does require a neutral.

webby_58 · Apr 21, 2012

Sorry thermostat... It seems the stat installed is simply a switch. Are you referring to a line voltage or low voltage stat....

snowhead · Apr 21, 2012

webby_58 said:
Confused.com as the boiler does not require a neutral connection ......?

The boiler already has a neutral, along with a live and earth.
The stat is switching a control circuit live derived from the boiler. (live + switched live)
The old mechanical stat didn't need a neutral
The new Electrical stat does need a neutral.
You either need a battery powered stat, or new cable as above to new electrical stat.

HandySparks · Apr 21, 2012

According to the Salus website and data sheet, the RT200 is an electronic thermostat. It requires a neutral to work. If you want to use this stat, you'll have to run a 3 core and earth as J&M says. The earth is not required for this stat but should be run anyway.