thermostat - wiring help

fryup

Need to wire up a thermostat for an oil boiler,

Not 100% on the diagram, can someone please help

the diagram

the thermostat

i take it the neutral goes to the right and live goes to the left, but where does the earth go? to the one in the middle or the one above it?

Doolittle51

Don't connect neutral to terminal 1. This would result in a direct short. Terminal 1 is the switched live to your boiler or maybe to a zone valve. Earth is connected to the terminal with the earth symbol on it.

kirk.

Ya it's just C and 1 no neutral connection , break on rise

CPC or earth connection too

fryup

^^^^

but Doolittle51 said don't connect to 1 ?

Doolittle51

https://www.boards.ie/discussion/comment/118470985#Comment_118470985

I said don't connect the neutral to terminal 1.

Terminal 1 will be live when the thermostat is calling for heat, so this is the 'switched live' signal. It's typical used to turn your boiler on or perhaps open a zone valve (which would then send a signal to turn your boiler on)

The 'U' shown in the wiring diagram represents the boiler or zone valve.

What's the thermostat for? Are you replacing a broken one? Or modifying the existing setup?

Wearb

@Doolittle51 Perhaps 1 becomes live on heat satisfied and 2 live on heat demand?

A simple check would confirm anyway.

fryup

https://www.boards.ie/discussion/comment/118472093#Comment_118472093

the oil boiler is for central heating i have it on a timer so it comes on in the morning & evening, i just want the thermostat to regulate the heat so that the radiators don't get too hot

Wearb

https://www.boards.ie/discussion/comment/118472765#Comment_118472765

The temperature of the radiators will not be controlled by a wall thermostat, just the room temperature, which is a good idea in any case.

If you want to control the touch temperature of the radiators, you need to turn down the boiler temperature, but that might result in not enough heat in the room.

fryup

^^^its not a wall thermostat, this thermostat sits on top of the oil boiler so it regulates the heat of the water within the central heating

Wearb

What's there already?

Doolittle51

Does the boiler not have it's own thermostat/controller to regulate the water temperature?

maestroamado

https://www.boards.ie/discussion/comment/118472765#Comment_118472765

There is already a thermostat on the boiler... is it broken...

fryup

^^it seems to be broken as the water is getting red hot within one hour

here's the wiring of the old thermostat, can i wire the new one the same way??

maestroamado

I would be reluctant to advise beyond turn the current stat all the way down and see what happens.

I got in trouble here for suggesting someone could dis-connect a wire... this be more serious...

Do you know if the stat is live-wired...

fryup

^^^ the stat is connected to a plugged in wall timer

Doolittle51

It looks like the existing thermostat is wired with 3 core T&E or flex. They've used the blue core as the switched live.

Probably best to get an electrician or boiler service engineer to look at this.

maestroamado

https://www.boards.ie/discussion/comment/118473201#Comment_118473201

Its very straight-forward... you likely get on google... the thermostat is the switch...

The color of the wires irrelevant in this case....

BTW the new switch is two way it seems...

meercat

https://www.boards.ie/discussion/comment/118472827#Comment_118472827

You need to get a different one.

You need a thermostat with a high limit stat incorporated if it’s controlling the boiler.

https://heatingpartswarehouse.com/product/imit-tlsc-dual-thermostat/?gclid=Cj0KCQiAoY-PBhCNARIsABcz77357xrBgvIL3Ibkvia2_4vYCuos1VtMdMJdbkpOPbfn8e_4WzeY7GQaAuxdEALw_wcB