thermostat

[jasonjkd]

Hi all Can I change a thermostat from a sunvic tlx2251 to a TLX7501.

Thanks

 

[sonray ltd]

yep
but what boiler are you running it on.

 

[jasonjkd]

It is a glow worm 38cxi combi, But my current thermostat has only got two wires 1 and 3 but the new one has got aspace for 3.

 

[sonray ltd]

you want 3 and 2.

3 is common (live call from boiler)
2 is switched live to tell boiler to come on
1 is off not used.

double check the instructions but thats it if i remember.

it is also low voltage.

 

[jasonjkd]

This is what my old one looks like. I have attached 2 photos if that helps.

 

[Deleted member 2053]

The tx7501 is spdt which means that it allows powering off as well as powering on. Most applications require a call for heat and therefore the advice given above is correct - leave terminal 1 unused.

 

[jasonjkd]

so what wire is which.

 

[Deleted member 2053]

If you only have two wires then it doesn't really matter except to purists.