Adding a room thermostat

If it is an old fashioned controller with a safety earth (usually) and three further wires to the boiler, common, water demand and heating demand (or only two if it doesn't control hot water) then putting the room thermostat in series with the heating demand wire as Roland initially suggested is by far the cheapest and simplest solution to do what Roland wants. (The fact some of us wouldn't want to control the heating this way is not his problem.)

If however the controller has one of the fancy bus connections popular nowadays the thermostat needs connection back to the "room thermostat" terminals on the boiler. On the old system these were probably used for Roland's controller, and in any case the boiler demand wire if it can be identified was available at the controller.

In message snipped-for-privacy@googlegroups.com, at

How are the smart-valves powered. Lots of individual batteries?

In message snipped-for-privacy@news.individual.net>, at

It's a small enough house that heat percolates around it even when room rads are off. But that wasn't really my question.

I understand about the short-cycling (but in practice the bathroom rad and the one in the former sitting room, now my office, are both warm almost all the time the heating is on), however if the room stat simply switches off the boiler like a timer would, does the circulating pump stop, and does in effect turning the boiler on and off several times an hour have any undesirable other side effects.

I'm not sure I could find a separate connection to make to the boiler to switch it by a thermostat rather than the timer. The timer just has one

It's a combi boiler and hot water is provided on demand even if there's no controller attached to the wall.

If you don't want the wifi integration fair enough, the models without that are certainly not complicated, e.g.

Conceptually I like the idea. Does the system create a "demand for heat at the boiler" as long as any smart valve needs it?

What kind of cost are we looking at for a full install in an average property? Not sure if the payback time is reasonable.

I hope your Alexa makes a better job of it than mine does of recognising music I am trying to ask for. The frustrating aspect is that there is no alternative interface.

Chris

You forgot to add the link to the receiver required to work with that Heatmiser transmitter; both would total around £70.

They are *all* complicated compared to what the OP wants, and I am speaking as one who has used wireless 'stats for around 15 years.

Our first one was a Drayton in about 2005, when we had a new boiler installed. It worked ok for three years until the receiver failed. It chose its time to fail carefully - we were just packing up the car to go off on Christmas Eve! It was freezing outside, and I luckily had kept the old wired thermostat in the "junk box". I connected it up in parallel with the Drayton receiver using a flying lead. It worked well enough to keep the house tolerably warm while we were away.

The second was one to replace the Drayton. Of course, I needed a new transmitter as well to go with the new receiver (not Drayton. The price of a new Drayton receiver alone was more than the prices of the transmitter+receiver of the new one. I can't remember the make, but it came from TLC). The new one had a faulty transmitter; it showed only all the LCD segments or none. I took it back and the replacement was fine. Except that the "Chinglish" manual was next to useless, as the setting up directions for the 4-position DIL switch for channel selection were nonsense. It took me some time to work out that their "left-right" meant "up-down", and what they referred to as switches 1, 2, 3, and 4 were actually 4, 3, 2, and 1. When I finally got the transmitter and receiver to talk to each other it worked well for 4 years until we moved.

A couple of years ago we had the boiler here replaced. I wanted a wireless stat again to replace the wired stat in the hall. We got a Salus RT510RF (an earlier version of

If the OP wants simplicity and reliability, an old-fashioned wired wall thermostat is the way to go. It will also be the cheapest.

In message snipped-for-privacy@mid.individual.net>, at 08:02:19 on Fri, 9 Oct

Could I wire that with one pair of conductors to the boiler? How is it powered. The site above has very little [actually, none] installation detail.

Yes

Then just put your thermostat in series with the controller. In principle if the controller is at mains voltage it would be best to put the thermostat in series with the live wire, but if they are both unearthed, double insulated it doesn't really matter. And if they are both extra low voltage it also doesn't matter which wire.

I suspect all modern boilers have pump overrun (and a permanent mains connection even when the controller is off) to stop the main heat exchanger getting too hot when switched off, and with old cast iron ones it doesn't matter.

I am sure your boiler has a way of switching off on demand water heating, which would save a few quid over a year by stopping short cycling to keep the water heat exchanger hot if you don't mind not having hot water immediately available at some hours, and save bits of the planet; but I have mine permanently on too!

In message <rlp584$1cp$ snipped-for-privacy@dont-email.me, at 08:58:59 on Fri, 9 Oct 2020, Jeff Layman snipped-for-privacy@invalid.invalid remarked:

Wouldn't it be possible to wire it to the boiler, so no transmitter/receivers required?

I already have a wire [2-core only] from where the timer (or timer/thermostat combo) is going to be installed, to the boiler.

In message snipped-for-privacy@mid.individual.net>, at 22:35:40 on Thu, 8 Oct

Yes, it's just two - the hot water is on demand 24x7 (combi).

The controller in my last house had a seriously multi-core cable back to the boiler.

In message snipped-for-privacy@googlegroups.com, at

I spend half my life changing/charging batteries. Don't need more to add to the millstone.

In message snipped-for-privacy@mid.individual.net>, at 08:15:26 on Fri, 9 Oct

The boiler is about 10yrs old.

Hot water isn't immediately available, it takes quite a while to start coming though. (I hate combi boilers, but replacing it is a project for another year, the new thermostat thing is just for this winter).

PS. An important point about modern room thermostats. 98% of easily available ones have a tiny heater to reduce hysteresis and need a mains neutral and live connection, and *must* be connected the right way round, it matters which is the mains supply side and which is the switched side. (It actually doesn't matter which is neutral and which live.) If you are not sure if your controller is mains or SELV from the boiler you need to find a so-called two wire room thermostat which does not need a neutral connection or

Off the top of my head I cannot recall all the costs but in our case it was all about comfort and convenience. We originally bought the Hive programmable thermostat and hub as we had one reception room that tended to lose heat quicker than the other and once the heating was in maintenance mode it would become a lot cooler than the room that had the thermostat in. We were able to move the thermostat into the cooler room as required but the drawback was the the room which normally had the thermostat became too warm. Although we could use a TRV in that room it caused issues when the thermostat was back in its normal place.

When the valves became available we bought a batch of five which covered all the radiators barring the bathroom which is the official system bypass and so is on whenever any device is calling for heat. As I said before we can now control the temperature room by room and can literally just heat the room we require without heating other rooms.

With the Hive system you do need the complete package of the Thermostat and valves as the valves communicate with the thermostat, I am not sure if you require the Hub as the system continues to work even if the internet connection is down, I think it is only really required if you want remote control over the internet. When we got the original Thermostat the hub came as part of the package then. The valves we bought as a batch which meant a discount on the individual valve price meaning one valve was essentially free.

There are other systems out there and it is worth shopping around with sales and discounts regularly available. All I can say is we are very happy with our system and the control we have so it was money well spent.

Richard

As mentioned elsewhere, you need to know if your controller is working at mains voltage or some extra low control voltage generated by the boiler. A simple two wire room thermostat (in series with one of your two cores - the other wire can be left intact or rejoined if the two core needs extending) is the only thing that is guaranteed to work without further investigation.

Yes, I mistakenly though that the device Andy referred to used a radio signal. But it is a "stand-alone" wired unit.

The connections required are shown here:

Then use a plain radio stat in series with the timer output

That's what your system currently is, but you're not happy with it?