Replacing room thermostat

[BJE46]

I am replacing a Satchwell TLX2259 room thermostat with a Danfoss FMT230D and need help with the wiring.

There are 3 wires to the Satchwell, yellow connected to 1, Red to 3, and blue to 4, with an earth wire connected to the backplate.

The Danfoss has two blocks on the wiring diagram, L and N, and then (NC off), NO (on), and COM.

Any help mapping one to the other will be greatly appreciated

 

[Whitespirit66]

Here's how to connect your new stat -

OLD SATCHWELL.........NEW DANFOSS
1/yellow--------------------NO
3/red------------------------L
4/blue-----------------------N

Then put a short link wire between L and COM.

 

[D_Hailsham]

Here's how to connect your new stat -

OLD SATCHWELL.........NEW DANFOSS
1/yellow--------------------NO
3/red------------------------L
4/blue-----------------------N

Then put a short link wire between L and COM.

The FMT230D is mains powered, not battery. If you wire it as suggested above the display will only be on when heating is ON at the programmer.

You either need to run a separate cable to power the stat, or use a abttery powered stat.

 

[Whitespirit66]

Yes, good spot.

If you want to install it properly with the display on at all times, wire it as follows -

OLD SATCHWELL.........NEW DANFOSS
1/yellow-----------------------NO
3/red--------------------------COM
4/blue-------------------------N

Then you will need to run a new, permanently live cable (ie. doesn't go on and off when heating turned on and off) to the L terminal. No need for any link wires.

The other way will work OK if you want to run it like that if you can't run a new live cable to stat straight away. If you are like many people who leave the ch turned on at the programmer and just use the room stat to turn the heating on and off, the first method would be fine as the display will stay on.