Replacing Drayton Tempus 2 with Refoss MTS200 wiring query

[WoodyAtWar]

Hi there,


I'm replacing a Drayton Tempus 2 with Refoss MTS200 and it's a little unclear which wire goes to where.

The existing wiring looks like this:

And the Refoss MTS200 looks like this:

What shall I connect and where?

Any help appreciated. Have trawled forums all over the place and nothing looks remotely like our ancient Tempus 2 wiring.

Thank you!

 

[RandomGrinch]

I had to search to confirm, but your single channel Tempus 2 had
Terminal 1 as common
Terminal 2 as Heat N/O
And Terminal 4 as spare.

Transferring that across:

N on Tempus to N (terminal 1) on Refoss
L to L (terminal 2)
Red in terminal 2 to NO (terminal 3)

Add a small link wire between L (2) and COM (5)

The blue (oversleeved red) and the yellow in terminal 4 can be joined together and safely isolated in a spare terminal block.

The green/yellow earth cables must be joined together and safely isolated in a separate terminal block, or the back box if it is metal.

As the existing spare terminal 4 is being used, this may suggest that you have a separate thermostat mounted somewhere?

 

[WoodyAtWar]

Wow, that's awesome! Thank you so much!

We do indeed have an old rotary thermostat elsewhere in the house. Assuming I can leave this disconnected?

Thanks again.

 

[ianmcd]

Wow, that's awesome! Thank you so much!

We do indeed have an old rotary thermostat elsewhere in the house. Assuming I can leave this disconnected?

Thanks again.

Depends whether it was working when you were using the Temps 2

 

[WoodyAtWar]

It does still work, albeit not well. Clicks off randomly.

 

[ianmcd]

It does still work, albeit not well. Clicks off randomly.

Then NO you cant simply disconnect it, you will have to either join the switching wires at the old thermostat end, or trace them and link and remove them permanently

 

[WoodyAtWar]

OK, will do that. Thanks everyone, installing tomorrow so fingers crossed

 

[RandomGrinch]

OK, will do that. Thanks everyone, installing tomorrow so fingers crossed

Good luck
If you post a pic of the wiring behind the old stat, we may be able to help you trace the connections.

 

[WoodyAtWar]

Thank you all. I will do that in the morning, let's get it right first time eh!

 

[ianmcd]

Think of the wiring as a circle, that is why it is called a circuit, to break that circuit you use a series of switches, either the programmer, or the thermostat, if you just disconnect the the thermostat you have broken the circuit so the other control whatever that may be can never complete the circuit as @RandomGrinch if you need any further assistance tomorrow post pics of the existing thermostat wiring and we will be happy to advise you how to proceed

 

[WoodyAtWar]

OK, installed and working as per all your advice. Thank you so much! Only issue is the external temperature controller in the other room is still dictating the temperature that the boiler clicks on and off at. Must be wired into the boiler itself perhaps?

 

[WoodyAtWar]

For reference here's the connections I made into the Refoss. And here is the ancient temperature selector:

 

[RandomGrinch]

Only issue is the external temperature controller in the other room is still dictating the temperature that the boiler clicks on and off at.

Either leave it turned up to 30, or..

If you post a pic of the wiring behind the old stat, we may be able to help you trace the connections.

 

[WoodyAtWar]

Well this is wiring behind the old Thermostat in the kitchen, where I've installed the Refoss:

And this is the wiring behind the room thermostat:

Thank you. Apologies I hadn't responded sooner to your request of a picture, I was being thick and thought you meant the existing thermostat image

 

[RandomGrinch]

Ok, try removing the red wire from terminal 3 of the Refoss, and putting the blue (oversleeved red) wire in its place.

If that works, the remaining wires from that (blue/red/yellow and earth) cable can also be disconnected.