Changing from "low voltage" to 230v thermostat

[ol1985]

UPDATED - SEE THREAD POST 29/11/11

Hi all,

You'll have to bear with me as i am a complete amateur when it comes to wiring/boilers/everything(? ).

I'm wanting to upgrade my existing Siemens RAA10 thermostat to a Heatmiser Wifi PRT-TS WiFi http://www.heatmiser.co.uk/web/index.php/wifi-thermostats

I've trawled through this forum and other websites but can't seem to find anything that matches my current configuration.

 

[simond]

This looks like an interesting idea, although the web interface obviously has been designed in an afternoon.

You will need a neutral to get this working; I cant make out the picture showing the cabling but assuming you have a flat 3 core and bare earth you can use the spare insulated core for the neutral.

I dont see any 24v there, if you have wiring knowledge then it is easy. If not, then bear in mind if you short it out you will probably weld up the tiny relay inside.

 

[ol1985]

That's the thing, I don't think it is a flat 3 core cable.

I've got 4 cables in total, a Brown Live (Going into L), a Black Wire with short Brown cover (Going into Y1, presumably "NO"?) and two other cables that aren't being used, a grey one and one that has no covering (both visible on second photo). I was expecting to see Brown, Yellow, Green wires so I'm at a loss now!!

 

[slup]

You should be able to use the grey wire as a neutral (sleeved blue). You'll need to check how it's connected at the other end though.

 

[slup]

You should be able to use the grey wire as a neutral (sleeved blue). You'll need to check how it's connected at the other end though.

 

[ol1985]

Thanks for your replies.

I've looked into it and the existing thermostat runs on low voltage.

The heatmiser needs to draw 230v but gives out volt free switching. What would be the best way to get 230v to the unit when the boiler only runs on low voltage? I am able spur from a nearby socket or light switch but not sure if this would be kosher. it'd also be easier if I could somehow send 240v through the existing wiring from the fused spur next to the boiler as this would mean no additional wiring/chasing. The exisiting wiring includes a neutral though is is redundant with the current thermostat.

There is no danger of sending 230v back to the boiler as I have checked with heatmiser and the unit only uses this to power itself

Thanks again

 

[D_Hailsham]

Which make/model boiler do you have?

 

[matt1e]

The heatmiser needs to draw 230v but gives out volt free switching. What would be the best way to get 230v to the unit when the boiler only runs on low voltage?

If your boiler supports 230v switching then reconfigure it as such
if it doesn't then use the heatmiser to switch a 230v relay fitted adjacent to the boiler and connect the boilers volt free connections to the relay's normally open contacts
or
run another cable in

Matt