Where to connect wires in airing cupboard for room stat?!?

[chrisburrows]

Dear all

Now that the cold weather is setting in, here come the questions about CH.

I had new CH heating installed a couple of years ago and only have Thermostats on the radiators, with no room stat because my plumber said that this is normal. The problem with this setup seems to be that I have to have the boiler on all the time just in case I need to heat a room and cannot control it without the Room stat.

My electrician who installed the wiring has just left a wire hanging in one room and the other end is coiled up in the white box in the airing cupboard, where all the wiring comes in and feeds the other bits such as programmer etc.

I have no idea where to connect this end of things and was wondering if anyone could shed some light on this for me?

Many thanks all

Regards

Chris

 

[clf-gas]

Have a look on here.

http://www.tlc-direct.co.uk/Technical/DataSheets/Horstmann/Index.htm

 

[JohnD]

how did you know it was a Horstmann programmer?

 

[clf-gas]

how did you know it was a Horstmann programmer?

Did,nt John, just shedding some light.

 

[chrisburrows]

Thanks for quick responses

It has a Honeywell Programmer. The Boiler is a Thermecon External Oil fired.

Just trying to get my head around it all because I don't want to blow the place up

Regards

Chris

 

[JohnD]

If you find the model number of the programmer, you can look up the wiring diagram (it will be on the manufacturer's website, or they will post you one), but they are fairly standard and fitting a room stat is not going to be complicated. If you can't find the model no post a photo of it and someone wil recognise it.

A typical programmer has about 8 to 12 terminals. If it is a bit cramped to get all your wires in, they also sell a "wiring centre" which is just a fancy name for a sort of junction box. It is quite a good idea to use wires in the recommended colours, as this makes it easier to check against the diagram, or at least to put coloured tape or sleeving round the ends. You can buy coloured wire by the metre.

 

[chrisburrows]

Thanks John

It is a Honeywell Y Plan set up with a ST 699 programmer. I have just found the paperwork for it. The only problem I can see is that there is no room stat in the system. It seems too simple to just wire in the stat as per the instructions.

I found this on another post here //www.diynot.com/forums/viewtopic.php?t=64409

and the CM907 is the new stat/programmer I would like to install. But I cannot make head or tail out of the wiring diagram and what it means. I am aware that I should only need to connect 2 wires, but where to??

The chap also mentions in this post that the old programmer shpuld be left in and switched to permanently on. Mmmmmm

Thanks

Chris

Excellent site by the way. Very grateful to you all here

 

[JohnD]

It seems too simple to just wire in the stat as per the instructions.

Too simple??

It's intended for plumbers you know

p.s. I've got one of those. http://www.honeywelluk.com/product.aspx?r=tco&p=2327 very easy to use

my installer wanted to fit a wireless wallstat but I asked for a wired one as I like to keep things simple.

Honeywell do a kit with the ST699 and a T6360 wall stat

 

[chrisburrows]

Hi John

Just editing my last post when you posted.....spooooooky!!! I already have the ST 699

Chris

 

[D_Hailsham]

It is a Honeywell Y Plan set up with a ST 699 programmer. I have just found the paperwork for it. The only problem I can see is that there is no room stat in the system. It seems too simple to just wire in the stat as per the instructions.

I am curious how the installer thought a Y plan would work without a room thermostat.

My electrician who installed the wiring has just left a wire hanging in one room

Hope that room does not have a TRV on the rad; but if it does it will have to be set to max so the room stat can work properly - or you can replace it with a wheel valve.

the other end is coiled up in the white box in the airing cupboard, where all the wiring comes in and feeds the other bits such as programmer etc.

Any chance of a photo of the inside of the white box, aka wiring centre, that will prevent any fruitless guessing how the system has been wired up.

The CM907 will only control the CH side; you will need to retain the ST699 for HW control.

 

[chrisburrows]

Hey ho

I have spent most of last night and this morning trying to figure the wiring out.

In hindsight, I should have used a different plumber as he stated that there was no need for any room stat.

The wiring center is full of all sorts and none labelled, ut by using the info sheets I have, I was able to detect which were which.

The thing that confused me was that the white wire coming from the zone valve was not wired as it should have been if a room stat was present, so I have been working out how to modify it slightly to incorporate the room stat.

I have now been able to wire in an RT 200 an all is working well. I did want to install an RM907 downstairs, but could not work out how to include it in this setup with the ST699 in the cupboard.

I have seen some threads that suggest all you have to do is leave the 699 on all the time and let the 907 take over, but I am not convinced.

I will see how things go with this setup. House is surprisingly warm considering no heating on and it is freezing out.

I didn't know about the TRV, so I have turned it up to full.

Thanks for your help all

Chris

 

[D_Hailsham]

The thing that confused me was that the white wire coming from the zone valve was not wired as it should have been if a room stat was present, so I have been working out how to modify it slightly to incorporate the room stat.

I have now been able to wire in an RT 200 an all is working well. I did want to install an RM907 downstairs, but could not work out how to include it in this setup with the ST699 in the cupboard.

I have seen some threads that suggest all you have to do is leave the 699 on all the time and let the 907 take over, but I am not convinced.

You seem to be doing all right without any help.

On a traditional Y-plan system, the thermostat is connected between the CH ON terminal of the programmer and the white wire of the valve. I suspect you just had the CH ON connected directly to the white wire.

Yes, some do suggest leaving the CH on permanently when installing a programmable thermostat. I think this is laziness. The correct way to do it is to remove the wire from ST699 CH ON to the wiring centre (insulate both ends to show it is not in use). Then connect the CM907 A terminal to the Live terminal of the wiring centre and the CM907 B terminal to the wiring centre terminal with the white wire attached.

The ST699 will then control just the HW times and the CM907 the CH times and temperatures.

 

[chrisburrows]

Great info

Many thanks

The way you have explained it makes it very simple to understand. I have been scratching my head trying to work out how to wire in the CM907

I will see how I go with the new basic stat and go from there

Regards

Chris