Wiring for a roomstat on a boiler?

[Lobster]

I'm fitting a 240V roomstat to a W-B 24i Junior combi boiler.

I've run 3-core-and earth cable from the roomstat position all the way to the boiler, where it emerges from the wall out of site behind the boiler position.

However, I understand that you need to use heat-resistant 3C&E flex within the boiler casing to connect to the terminals within, right? So where is the correct place to interface the cable and the flex? The only way I can imagine doing it 'correctly' is having a box sunk into the wall below the boiler, adjacent to it's FCU, with a flex emerging and leading to the boiler's roomstat terminals. But I've never ever seen that done in practice... what's the solution? (Difficult for me to do at this stage anyway, after the event...)

Thanks David

[Lobster]

The plot thickens I'm afraid: as well as the above, can anyone confirm for me what the connections are on the roomstat (Honeywell T6360)? It's all nice and clear in the boiler instructions - it tells you "live", "switched live", "neutral" and "earth"; however I can't figure out what to do at the roomstat end. Here's the relevant circuit diagrams (identical to the ones on my instruction sheet:

or

Bit ironic, this, because the reason I chose a W-B built-in programmer with just a simple external roomstat was that I was worried about potentially complicated connections - and whaddyaknow - I still can't do it! :-(

Many thanks in advance

[John]

Terminal 3 is the "Switched Live" - I guess you know the others

[Lurch]

On Sat, 28 Apr 2007 09:48:56 GMT, Lobster mused:

I usually use a 5 core flex from the spur and use the 2 'other' wires (not the live, neutral or earth) for the room stat connections. The neutral for the stat comes straight off the spur. In the boiler just connect the 2 stat wires to the 2 room stat terminals, ensuring that you get the live to the live and not the return live connection.

Other option is as you say, a flex outlet with a seperate 4\5 core flex to the boiler, I don't do that very often as the 5 core flex from the spur is easier.

[ARWadsworth]

Not fair. I wanted to say that.

Adam

[Lurch]

On Sat, 28 Apr 2007 21:02:04 GMT, "ARWadsworth" mused:

Got to be in it to win it. ;)

[Lobster]

Hmm. Well I checked today by testing for continuity across the terminals as I rotated the thermostat dial; AFAICS the only permutation which for which the dial affected continuity was terminals 1 and 4 - from which I deduce that terminal 4 is the switched live: correct? Not a wonderful basis on which to proceed; I'd rather be clear from the instructions which terminals are which but as I said I don't follow them... anyone able to help?

Thanks David

[Lurch]

On Mon, 30 Apr 2007 13:31:36 GMT, Lobster mused:

From the instructions and the clear wiring diagram it says.

1 - Live 2 - Neutral 3 - Switched live to heating load 4 - Switched live to cooling load

[Lobster]

Great, thanks Stuart. Have to confess I can't understand where you get 3 and 4 from!

Is this configuration consistent with the results of my continuity tests (above)? Because if I put my multimeter leads across 1 and 3, there was apparently no change in resistance when I adjusted the stat dial over its full range.

David

[Lurch]

On Mon, 30 Apr 2007 16:56:29 GMT, Lobster mused:

The diagrams are pretty standard to any room stat.

According to the diagram for the T6360 (the middle one on page 2) that's what the terminals are. I can't say as I have ever actually tested one, I just read the instructions for the pinout and wire it up, and it works.

[Phil B]

I'd agree with Stuart based on the info given. If you get open circuit between 1 and 3 even with it turned to max temperatore then the thing is broken.

Out of interest, the little resistance shown between 2 and 3 is an 'anticipatory heater'. When the thermostat demands heat it heats up faster then the surrounding air, and shuts off quicker. When cooling, there is no current through the resistance so it cools quicker. Hence it has less 'backlash' and is more responsive. If you omit the neutral on pin 2 then it seems to work but you get wild swings in temperature.

I used to have an old one in the drawer and went to check it out - sadly no longer there - SWMBO has been tidying I guess. But - if you need a new knob for it there I can help you!

Phil

[Lobster]

Thanks very much, both. Will suck-it-and-see tomorrow - the stat's brand new so if it *is* up the spout it can just go straight back!

David

[Lobster]

Just following up with another thank-you - boiler's now up and running with the roomstat working fine (and wired as instructed above :-) )

David