MTS200 wall thermostat installation - Myson system

[Pedropuk]

Attached photos of current wall thermostat which I think should be compatible. Has live, neutral and a control wire all feeding from the central heating / boiler wiring.

From the wiring diagram on the existing Myson

MRT1 it should map over as 1 (Brown) live 4 (Black) neutral and 3 (Grey) control. I assume normally open because the heating will only turn on if the room drops below the set temperature. Then need to bridge L to COM as per other threads I have read to power both the device and heating circuit.

So this should work if my heating programmer is always set to on (for central heating).

Can anyone confirm my understanding of this wiring or has contacted to a similar central heating system?

 

[ericmark]

In the main, N/O connects as the thermostat cools, although have had thermostats with a selection switch, so N/O connects when it heats, for when used with air conditioners.

N/O means if no power no connection, so you need to read the instructions, or use a meter.

The old thermostat used a heater to reduce the slewing differential but they would still work without the neutral connected, so again you have to check.

But you seem to have worked it out OK, so not sure why the question, so listing why it may not work.

 

[Pedropuk]

Not following your point here “N/O means if no power no connection, so you need to read the instructions, or use a meter”

But reason for posting is the black neutral wire threw me a bit (was expecting blue), and also Meross support telling me to wire that (Black) into Live of the new smart thermostat - which makes no sense.

So checking my logic / reading / and sanity with someone more knowledgeable or has replaced the same previously.

 

[ericmark]

Brown = line
Black = neutral
Gray = switched line
You have labelled correctly
N/O = normal open, normal means state with no power.
So brown to 2 and 5 (L and com)
Black to 1 (N)
Gray to 3 (N/O)

 

[Pedropuk]

Perfect thanks for confirming.