New CH system controls and thermostats

Trying to get my head around what controls are needed for a new CH system for compliance with the regs... could someone confirm I've got this right?

Gas-combi system; rads in all rooms (incl kitchen and bathroom) plus hall downstairs (but not the landing). I was going to fit TRVs to all rads except the one in the hall, where a roomstat would be fitted. Or should the roomstat (and no TRV) be fitted in one of the downstairs living rooms instead?

Secondly - as I haven't got as far as selecting a room thermostat but am at first-fit stage with the general rewire - can anyone confirm whether I'm correct in thinking that a single length of 1.0mm2 T&E cable between boiler and thermostat positions will suffice (with presumably a second such cable as a spur from a ring main, unless the item is battery-powered only?)

I may want to go for a combined roomstat/timer unit - or would that be more awkward for a muppet to install than a separate roomstat and going with the boiler manufacturer's built-in programmer option?)

Thanks a lot David

Reply to
Lobster
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You must only feed power into the heating system at one point, usually next to the boiler. If it's a battery-powered stat you only need to run a single T&E cable from the boiler to the stat, 3C&E for a mains stat. Depending on where the stat is you might want to consider a wireless one.

No - the wiring for a CM67 or similar is no different to an ordinary battery powered stat.

Reply to
Tony Bryer

There's no simple answer to the question about where to put the stat. Put it in a room which you mind being slower to heat up than the other rooms - so that the stat keeps the heating on until all the TRVs have turned off. Don't put it where there's an independent source of heat - like a gas fire or cooker - or where it will get an icy blast when you open an outside door.

Go for a battery powered programmable stat. Some combis send only a low voltage signal to the stat, and need it to have volt-free contacts. A battery power one is happy to switch either low voltage or mains - and won't need an earth, so you just need a 2-core cable between it and the boiler. A programmable stat also lets you have different temperatures at different times of day - and some have additional fancy features like Party mode and Holiday mode.

Reply to
Roger Mills (aka Set Square)

The CORGI guy who installed our system has placed a rad without TRV in the hallway and mounted the wireless digital thermostat on the landing and the system works really well.

Have a look at

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It won't be any use to you unless you happen to be installing an Alpha boiler, but you may be able to get an equivalent thing for whatever your boiler is.

Dave.

Reply to
Dave

Thanks for all the advice. Reckon I'll be going for a battery-powered roomstat then, and I'm sure it has to be less aggro to stick with a manufacturer's programmer built in to the boiler (nobody's commented on that though?!)

I think a good place for the roomstat might be on the landing (which will have no rad). However, the easy and logical place (ie, on a 'still-under-construction' stud partition) it would be 'round the corner' from the stairwell, and quite a long way from the hall rad. Is that likely to be a problem, practically and/or regs-wise? This stat would actually be quite close to the TRV-controlled rads in the bedrooms, if the bedroom doors were open.

By the way, does anyone know of a good on-line resource where I can get chapter and verse - in plain English - on this stuff?

Cheers David

Reply to
Lobster

Then I will! It may be less aggro - but it's also a lot less flexible. The boiler's programmer will simply be an an/off timer, and when it is on you'll get whatever temperature is set on your room stat. However, if you leave the boiler's timer permanently on, and use a programmable stat such as a Honeywell CM67 to do the timing and the temperature control, you'll have additional features such as:

*different temperatures at different times of day (and on different days of the week if you like)
  • optimum start - only starting the boiler at the right time to get the house warm by the specified time
  • automatic frost stat - which will bring the heating on when not otherwise programmed if the house is in danger of freezing
  • Party mode - which enables you to over-ride the temperature setting for a specified number of hours. [Can be used to extend the heating period for a genuine party - or, for example, to set a lower temperature when you go out shopping, but crank it back up just before you expect to get home]
  • Holiday mode - which enables you to turn the heating off (except for frost stat function) for a specified number of days - and then to return to normal function. So you can save energy while away, but still return to a warm house.

And no, I'm *not* employed by Honeywell, or anyone else for that matter!

Reply to
Roger Mills (aka Set Square)

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