I thought I might get a useful suggestion here.

Polypipe UFH/Water controlled by a PB2CTC 2 channel time clock. Unlike every other time clock I've so far found, this is powered by 2 AAA batteries and just switches two relays (so there is a live in and return for each of heating and hot water). The time clock, of course, stops working when the batteries run out. And it's so unintuitive to programme and read that no-one can use it.

The wiring centre is not local to the time clock so, while a permanent live to a new time clock is easy enough it would be much easier to install if the wiring at the wiring centre remained the same

Any suggestions for a new, idiot proof, control system? A pair of seperate time clocks labelled 'water and heating ' would be ok, but of course most of these take the form of fused spurs that are designed to send a live and neutral - not just close a relay.

It's odd that it isn't already wired with a single permanent live supplying the two switched lives, is there a reason?

We had a similar ish problem a while back with a light switch where no neutral was available where needed. We ended up using self powered wireless switches that control mains powered wireless relays, the relays are easy to locate near to the load where there is a neutral (or the wiring centre in your case) and the switch floats around the living room with the TV remotes. Great kit, there's no need for wires to run in walls to switches anymore. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16243

There are quite a few time/temperature controllers which have battery wireless faceplate units which talk to a wired base station located near the wiring centre, or there's the new world of internet controllers which you adjust from your phone or your Alexa.

this is the rear of the unit.

And what I want to fit.
- clearly shows whether each of hot water is on or off, using words not non-standard pictograms (so the Polypipe can have up to 4 channel - how the hell you know which of them is active at any time given the possible display info is beyond me)

- when you're programming it you set on and off times rather than times associated with a picture of a man/sun/bed/house/moon
- has labelled physical buttons to switch the water/heating on/off and between modes. And for good measure, an LED that lights up when it's actually active.

rant over...

it's a rental flat, so don't want smartphone control of the heating. (and in any case, in a well insulated house I think theres minimal benefit)

Posted By: WillInAberdeen

We had a similar ish problem a while back with a light switch where no neutral was available where needed. We ended up using self powered wireless switches that control mains powered wireless relays, the relays are easy to locate near to the load where there is a neutral (or the wiring centre in your case) and the switch floats around the living room with the TV remotes. .

those piezo powered light switches are brilliant - iv'e seen a few people with them installed recently saving masses of difficult wiring to put the switch where they wanted it.

Couldnt quote for some reason, so deleted

Posted By: philedge

Posted By: Simon StillBut putting batteries in hardwired stats and controllers is just shit product design.

Many of the programmable battery powered stats are intended to be direct replacements for older mechanical stats that would only have a 2 core cable run to them and no way to mains power them without a rewire. Thats likely why they are battery powered so they are an easy upgrade.

When you do your wiring changes dont forget to add a brown sleeve to the blue wire used for a switched live. The brown sleeve is a handy little reminder/belt saver for you in the future!!

No, that's what's so absurd - the room stats aren't smart - they've a conventional dial for temperature, nothing more, and a switch under a flap so you can turn them off. But they need two AAAs!

Rewired today. Of course there were two wiring centres - one for the heating and one for the hot water. I took the live from one, the neutral from the other. And all the wires are correctly coloured/sleeved.

Posted By: Ed Davies
So, it seems to me that you can do this easily enough by moving one wire inside with wiring centre so one of the existing two permanent lives becoming the new neutral.

Cheers Ed.

>>> "Of course there were two wiring centres - one for the heating and one for the hot water. I took the live from one, the neutral from the other."

Dunno what the regs say, but I would prefer to avoid that, if possible. Let's say someone isolates one of the systems to work on it, you don't want this arrangement to cross power across from the other system and make it unexpectedly live, eg at some random time when a programmer switches itself on.

I would tend towards keeping the heating system switch powered from the heating wiring centre, and energising the heating system and using the heating neutral, and the hot water switch doing that from the hot water side. Use relays if necessary to achieve this.

I'm not a sparky so maybe this is just me and not accepted practice!

If unavoidable, perhaps stick a big label on each system to warn future generations to isolate both systems before working on either?

Edit: do they both come off the same circuit breaker and fuse connection unit?

Posted By: Simon Still

No, that's what's so absurd - the room stats aren't smart - they've a conventional dial for temperature, nothing more, and a switch under a flap so you can turn them off. But they need two AAAs

The pictures/menu you posted earlier look like a programable stat with digital display but unlikely to be smart by todays standards as in no wifi/internet/app control. Theyre still digital and need power thats unlikely to be available with the mechanical stats they were intended to replace, hence the batteries

Devices were.."But putting batteries in hardwired stats and controllers is just shit product design."

Hopefully explained above why programmable stats evolved as battery powered.

Posted By: WillInAberdeen>>> "Of course there were two wiring centres - one for the heating and one for the hot water. I took the live from one, the neutral from the other."

Dunno what the regs say, but I would prefer to avoid that, if possible. Let's say someone isolates one of the systems to work on it, you don't want this arrangement to cross power across from the other system and make it unexpectedly live, eg at some random time when a programmer switches itself on.

Edit: do they both come off the same circuit breaker and fuse connection unit?

I did think this BUT it all runs off the same fused spur so while I agree it's not optimal, I don't think it's dangerous and, given it's wet underfloor that uses the same tank as the hot water (which gets heat via a heat exchange unit powered by a central boiler for the whole development) it should be fairly obvious what's been done.

Posted By: philedgeDevices were.."But putting batteries in hardwired stats and controllers is just shit product design."

Hopefully explained above why programmable stats evolved as battery powered.

If they were in any way programmable I'd forgive them, but they have simply replaced a completely dumb mechanical room stat, with a completely dumb electronic room stat than requires AAA batteries. I've not taken one off the wall but I'd guess it enables a 2 wire install rather than a 3 wire, but this is for underfloor systems so it was always going to be a completely new install and cabling.

Posted By: philedge

Posted By: Simon StillBut putting batteries in hardwired stats and controllers is just shit product design.

Just have a look at some of the instructions. Pictograms which it doesn't define, which don't quite match between the instruction and the screen display, and that are so small in reality you can barely make them out (especially if the unit is mounted side on inside a cupboard.

Im guessing the dumb units youre talking about are not those that you posted the programming instructions for??

It's really not that complicated. There is a single 2 channel programmer - heating and hot water - that's what I posted the instructions for.

Each room/underfloor heating circuit has a dial based room stat to call for heat in that room. Both the programmer and the room stats require AAA batteries, despite having cable connections to the wiring centre.