Can you help me with wiring my 2-wire Boiler Thermostat

[Doran]

Hi there,
Hopefully this is an easy one.. I just don't want to get it wrong.
I am replacing my old analogue 2-wire thermostat, with a battery powered programmable 2-wire thermostat.
I am just wanting to make sure i use the correct terminals on my new themo.

this is my old one.. two wires, yellow and red.


this is my new one. with holes numbered, 1, 2, 3, 4, and earth
and this is some of the manual.
http://horstmann.securemeters.com/f...ller_guide_c-stat_11-B-17-B-Installation1.pdf


If anyone can tell me which wire should go to which hole, that would be great.

Thanks in advance.

 

[stem]

Red wire goes to Horstmann thermostat terminal 1
Yellow wire to Horstmann thermostat terminal 4

There may be blue wire hidden away at the back of the existing thermostat which may be connected to a neutral. You don't need it, but insulate it and tuck it out of the way if there is one.

Also, whilst the Horstmann is double insulated and doesn't need an earth connection, if there is an earth wire present, park it in the terminal provided to keep it out of harms way.

 

[Doran]

Amazing. thank you. That's great!

One other question.. do i need to fully turn off all my electrics to wire this thing up?
the manual says it has "voltage free contacts".. but.. I'm not sure if that totally means i can do this with my electrics on.

 

[flameport]

do i need to fully turn off all my electrics to wire this thing up?

Yes you do.

'volt free' means the contacts themselves have no voltage - but the wires they will connect to certainly will.

 

[stem]

If by "all your electrics" you mean your entire house (garage, oven, lights, hot tub, sauna, Tesla charger, etc.,) then no. You only need the wires that you will be working on to be isolated. I usually just isolate the boiler followed by a quick check with a multimeter to make sure that the wires I am working on aren't live. However, if you aren't able to check this, it's best to be safe and turn off the main supply.

 

[ban-all-sheds]

I usually just isolate the boiler followed by a quick check with a multimeter to make sure that the wires I am working on aren't live.

Having first proved, I hope, that your meter is working....

 

[Doran]

Red wire goes to Horstmann thermostat terminal 1
Yellow wire to Horstmann thermostat terminal 4

There may be blue wire hidden away at the back of the existing thermostat which may be connected to a neutral. You don't need it, but insulate it and tuck it out of the way if there is one.

Also, whilst the Horstmann is double insulated and doesn't need an earth connection, if there is an earth wire present, park it in the terminal provided to keep it out of harms way.

Would you mind explaining how, from the schematics you know red goes to 1, and yellow goes to 4? I'm just curious.

Thanks

 

[stem]

I don't mind at all. It tells you in the manual you posted the link to.

A thermostat is just a switch. When heat is required, the two wires are connected together inside it.

The supply usually goes to the 'common' and as the red wire currently is the live supply to your existing thermostat, goes to 'common'. The yellow wire goes to the other side of the contact that is energised when the C-Stat 'Calls for Heat'.