Adding Room Thermostat

[imroberts]

Just moved into a flat that has a SD Thema F23e boiler. I know a lot of people don't like them so no need to labour that issue

I'm a bit confused about the heating aspect of things..

1) There is no room thermostat, however all except the bathroom radiator have thermostats. Now I understood that the boiler would run until all the temperatures are upto temp (it would detect that the water on the return was the same temperature as that on the flow, and shut down). However the pump in the boiler seems to run all the time, with the boiler firing up and down periodically (presumably when necessary). Is this correct?

2) I would rather fit a room thermostat so that the boiler will switch off when the main living area is upto temperature. This will also give me more flexibility as to when the boiler is running or not. Am I right in thinking that a normal thermostat will only require two wires from the boiler, which basically operate like a switch?

 

[breezer]

2) yes. but it should be a twin and earth

 

[imroberts]

2) yes. but it should be a twin and earth

Ok. Guessing I should leave the earth free?

What rating does it need to be for the above boiler?

 

[gasandoilman]

1.5 flex

 

[imroberts]

1.5 flex

Excellent. I'll get that sorted later this week

 

[gas4you]

1.0mm twin & earth will be fine, or 0.75mm cable (heat resistant as it will terminate in the boiler), it is protected by a 3 amp fuse so no more than 750 watts can go through it.

Why not fit a wireless stat and save a lot of installation hassle

 

[imroberts]

1.0mm twin & earth will be fine, or 0.75mm cable (heat resistant as it will terminate in the boiler), it is protected by a 3 amp fuse so no more than 750 watts can go through it.

Why not fit a wireless stat and save a lot of installation hassle

I was actually debating a wireless thermostat but the one I want is 10x the price of a standard one

Hadn't thought that the boiler was protected by a 3amp fuse anyway, guess I'll go for 1mm cable then it's easier to get down the plasterboard

 

[gas4you]

Yes but think of the work/labour saved with a wireless unit.

 

[imroberts]

Yes but think of the work/labour saved with a wireless unit.

Yeh... Hmm... Why are major life decisions so hard :'(

 

[imroberts]

1.0mm twin & earth will be fine, or 0.75mm cable (heat resistant as it will terminate in the boiler), it is protected by a 3 amp fuse so no more than 750 watts can go through it.

Why not fit a wireless stat and save a lot of installation hassle

I didn't know you can get heat resistant twin and earth... would heat resistant 13A flex be suitable or should I only use twin and earth?

 

[simond]

You can't. Dave was referring to the 3183Y three core flex.

 

[imroberts]

You can't. Dave was referring to the 3183Y three core flex.

Ah I see

 

[imroberts]

Got a Honeywell T6360 thermostat

I assume for a "two wire" connection I connect direct to terminals 1 and 3... and if I had a cooling system this would be connected between terminals 1 and 4...

I'm a bit baffled what purpose terminal 2 serves and under what situations this would be connected? Some sources online seem to suggest the heating should be connected across terminals 2 and 3 which is obviously (I hope) not right...

 

[D_Hailsham]

You can see the T6360 wiring diagram at:

http://content.honeywell.com/uk/homes/Catalogue/Heating Controls/2.17 T6360.pdf

It's a PDF so you can save it to your computer.

As you will see from the diagram, terminal 1 connects to the supply (usually the output from the time clock and terminal 3 to the boiler/pump. Terminal 2 connects to the Neutral. There is a resistor between 2 and 3. This is called an anticipator. The purpose of this is to reduce the wide variation between on and off temperatures you get in a mechanical thermostat. The room then feels more comfortable.

You need to have the neutral connected. If you do not have a three-core plus earth cable to the thermostat, you can always use the neutral of a 2core+earth for the feed back to the boiler, but it is not good practice and you should use a bit of black insulating tape over each end to show that it is a switched live. The earth lead would then be used as the neutral and should be insulated and labelled. [/b]

 

[imroberts]

Ok, that makes sense basically means the room doesn't have to drop to arctic conditions before the heating comes on?

Im guessing with my particular boiler, I just connect the two terminals on the below diagram across terminals 1 and 3, cos the boiler doesn't require a compensating resistor?

http://www.imroberts.co.uk/ThemaF23e.JPG