Replacing my old satchwell thermostat

[Callum19999995]

Currently trying to replace my old satchwell thermostat, I was given a heatmiser slimline v2 but I’m struggling to get it going, I’m wiring it as :
Red - live
Blue - neutral
Yellow - switch live
Bare- earth


On the heat miser I’ve followed the instructions and put a live loop between live and a1, it’s got power but nothings happening on the screen ??

any ideas or recommendations on a different thermostat that will work with my system boiler

 

[CBW]

You sure live and switched were correct? Have you tested any of it?

 

[Callum19999995]

You sure live and switched were correct? Have you tested any of it?

Yep red’s definitely live and is live and I’m pretty certain yellow is the switch back, could it be a faulty thermostat, it was left over from a job I done and has been sat in my spare room for 12-18 months

 

[EFLImpudence]

This is the only diagram I can find.

It suggests that 2 (blue) might not be Neutral.

Can we have a picture of the diagram that goes off the bottom of your picture?

 

[Callum19999995]

This is the only diagram I can find.

View attachment 228367

It suggests that 2 (blue) might not be Neutral.

Can we have a picture of the diagram that goes off the bottom of your picture?

 

[333rocky333]

Post a pic of the wiring diagram on the old stat, i too dont think Blues a neutral they tended to use Terminal 4 for the Neutral

Often like this

 

[Callum19999995]

Post a pic of the wiring diagram on the old stat, i too dont think Blues a neutral they tended to use Terminal 4 for the Neutral

 

[Callum19999995]

Post a pic of the wiring diagram on the old stat, i too dont think Blues a neutral they tended to use Terminal 4 for the Neutral

Often like this

My earth (bare ) is where the blue is and my blue is in between the red and yellow in this picture

 

[EFLImpudence]

Here is a clearer one:

1 and 2 are switched lives as per my previous diagram.
The N on the thermostat picture diagram only applies after the appliance M.

I think you need to find the other end of the cable and see what it is connected to.
Whether the bare (earth) wire is being used as a Neutral is not clear.

 

[CBW]

In the photo where it’s just wires, where’s the bare wire gone? Are you able to safely test these?

 

[ericmark]

As @EFLImpudence says the Neutral is an option with old thermostat, it reduces the hysteresis if connected, but will work without it, and with a modulating boiler using TRV on every radiator so the wall thermostat is only to turn off boiler in summer months having a large difference between on and off temperatures can be an advantage.

So big question is if the neutral is actually connected at the other end of the cable?

 

[Callum19999995]

As @EFLImpudence says the Neutral is an option with old thermostat, it reduces the hysteresis if connected, but will work without it, and with a modulating boiler using TRV on every radiator so the wall thermostat is only to turn off boiler in summer months having a large difference between on and off temperatures can be an advantage.

So big question is if the neutral is actually connected at the other end of the cable?

Got it going today, the neutraL wasn’t connected at the other end

 

[Callum19999995]

But thanks all for your help

 

[EFLImpudence]

That's good to know.

However, for the future please remember that Blue does not mean Neutral.
Neutral is the name given to the conductor(wire) which completes the circuit from the load(appliance) back to the supply.
Wires can be anything we want them to be; they do not know what colour they are.

As it was, on your old thermostat the Blue was an unused Switched-Live.
Had it been connected to an actual Neutral at the other end there would have been a BANG when that Blue became live.