Thermostat wiring advice: Honeywell 6360 to BHT-6000

[Deleted member 267285]

op has same set up.

Well technically no, as op has a neutral wire. Only way forward is run new wiring, new wireless thermostat (placing receiver near boiler or wiring center) or battery operated thermostat, or keep existing.

 

[Brian Mcwilliams]

thanks for advice

 

[stem]

op has same set up.

Almost, but as @CBW he does have the neutral connection that you don't.......If only the original installer had done his job properly.

If you wanted to install a more up to date thermostat without altering the wiring, you could install a battery operated one.

Tado manufacture a wired WiFi enabled thermostat that is battery operated. You can find the details here. The wires you now have in terminals 1 and 3 would simply go to terminals COM and NO.

 

[fixitflav]

With the original thermostat, the switch is directly connected to the live internally, and as you have figured the new switch is 'dry' or 'voltage free' The reason for this is that more recently, some combi boilers have 24v control, and the voltage free contact allows the thermostat to be connected to either voltage, 230V or 24v. As you want to switch mains voltage you get it via the link between terminals (1) and (4)

A general question - why does the new stat have a neutral? Does it have a booster heater? If so, it would be between terminals 2 and 3, OK if the switched voltage is 230V (and the link in) but there's only one set of contacts and booster obviously no good for both 24V and 230V. If no booster, why have a neutral?

 

[Deleted member 267285]

A general question - why does the new stat have a neutral? Does it have a booster heater? If so, it would be between terminals 2 and 3, OK if the switched voltage is 230V (and the link in) but there's only one set of contacts and booster obviously no good for both 24V and 230V. If no booster, why have a neutral?

It requires a permanent live an neutral for power.

 

[stem]

Do try and keep up, I explained that in my first post

The old stat is purely mechanical, so it will work without a neutral....the new thermostat is mains powered so it requires a live and neutral 230V supply.

 

[fixitflav]

It requires a permanent live an neutral for power.

Do you mean a permanent live while the programmer is calling for heat? It only has one live. To power what? The Modbus or the NTC (whatever that is doing)?
Unless there's a booster, neutral is not needed for switching the CH. Many years ago I had a Honeywell roomstat with 3 wires, live, switched live and earth. Worked fine.

 

[fixitflav]

Do try and keep up, I explained that in my first post

That was in your #14. But it doesn't explain why. No obvious reason why the switching mechanism needs power (and hence a neutral), ones with bimetallic strip or sealed system don't have it. With or without a booster heater, though with gives finer control.

 

[Deleted member 267285]

Do you mean a permanent live while the programmer is calling for heat? It only has one live. To power what? The Modbus or the NTC (whatever that is doing)?
Unless there's a booster, neutral is not needed for switching the CH. Many years ago I had a Honeywell roomstat with 3 wires, live, switched live and earth. Worked fine.

Are we getting metaphorical wires mixed up? I’m on about the BHT6000, not the Honeywell.

 

[fixitflav]

Are we getting metaphorical wires mixed up? I’m on about the BHT6000, not the Honeywell.

I'm asking about the new one, the BHT-6000. The Honeywell needs a neutral as it has a booster heater.

 

[Deleted member 267285]

The Honeywell needs a neutral as it has a booster heater.

Yes, I’m aware of this.

Right, so the new BHT 6000 - it’s a smart WiFi thermostat, non mechanical, non battery operated, how else do you expect it to work?

 

[fixitflav]

Yes, I’m aware of this.

Right, so the new BHT 6000 - it’s a smart WiFi thermostat, non mechanical, non battery operated, how else do you expect it to work?

I don't know how smart the BHT 6000 is, or whether it has WiFi capability, but here it's used wired, heating on via terminal 2.

If it needs power (and neutral) to close the contacts, as it apparently does, unlike more traditional types, I can understand. But I didn't know that before I asked, and I'd be interested if anybody can explain in more detail how it works.

 

[milgo123]

As well as being a thermostat It replaces the function of the clock/programmer so needs to powered all the time so as not to lose any settings.