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230V or Volt Free Stat which one do I use?

Postby cemhlm » Sat Dec 20, 2008 12:13 pm

About 1 month ago I changed my old electr-mech Thermostat for a Digital Stat, it was easy to do, the new Stat a Sunvic 7501 required a 2 wire connection - Live and Call for heat, no neutral or earth was needed, 2 x AA batteries provoded the power to the Stat. Since installing the Sunvic it became obvious that the Stats position is just to near the kitchen door, when the door is opened the heat from the kitchen turns off the stat, keeping the kitchen door shut is not an option, moving the Sunvic is also not an option. The solution is a Wireless RF Stat, I can then place the Stat away from external heat sources.

The RF Stat I have found which is easy to use is the Salus RT300RF Model, the Installation instructions can be found if you visit "" and then search for the correct manual.

I do not want a Programmable Stat, this model allows easy to use up - down and set options nothing else, anything that requires programming is a no no for my wife, she has a mental block on all things high-tech.

If you look at the installation instructions there are 2 options for wiring this model, 230v and volt free, bearing in mind how the current Stat is wired ie Live and Call for heat, am I right in assuming that the 230v wiring is the correct option for me. wiring in the L and N seems straightforward, but the Call for Heat wire is not so obvious looking at the diagram the SL position is where this wire would go. as the diagram states that * is not normallu used, which one do I use?

Any advice is apprecaited.
Last edited by cemhlm on Sat Dec 20, 2008 4:47 pm, edited 1 time in total.
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Simply Build It

Postby plumbbob » Sat Dec 20, 2008 2:18 pm

This is a tad more difficult than it sounds.

The main problem is the thermostat needs an extra wire that will not be available. Remember the live you already have is only live when the timeclock is calling for heat. The thermostat needs a permanent 24hr live for it to operate and remember it's settings.

As there is a timeclock in the circuit (I am assuming this is so) you should use the volt free option otherwise the timeclock will be bypassed.

The connections are

L = 24hr permanent live
N = Neutral
Com = Existing live to old thermostat
NO = Switched live to boiler (Call for heat)
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Postby sparx » Sat Dec 20, 2008 9:41 pm

see my answer on leckie post
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