Home heating automation

What are the 'they' that only gets power from the valves? The mains Live path for a two zone valved (CH and HW) system with a Tado wireless receiver (aka extention kit) as the controller, this yoke,

is as follows:

Mains Live permanently into the Tado receiver to power it. Battery power to the Tado Wireless CH wall stat, which controls the CH relay in the Tado receiver. HW timer in the Tado receiver controls the HW relay. The app also controls both. The switched Live from each relay is sent to the motor control of their respective zone valve motors, one each to their brown wires. These Tado SLs go nowhere else. The zone valves are actuated by these SLs, (permanent Neutral is connected to their Blue wires), and the valves open the heated Flow. So far so good.

The valves also have built in relays with 2 (sometimes 3) wired connections. The Grey wire is the Common terminal and the orange is the Normally Open terminal. (optional white wire is NC terminal). A permanent live voltage is connected to both valves' grey wires, (not the relay lives from the Tado). The valve relays when actuated connect this Live to their respective Orange wires, which leaves the valves as SLs to the boiler, and both Orange wires are joined, so each valve will call the boiler when either relay closes. This relay arrangement means that one zine opening can't backfeed and open another zone's valve.

The HW SL from the Tado receiver to the HW zone valve may also optionally pass through a HW cylinder mechanical thermostat, which will interrupt the HW call to the HW zone valve, and thus that zone valve's relay SL to the boiler. Again, I'm assuming your tem 'RF switch' refers to the Tado receiver. Otherwise I'm on a wild goose chase.

Sounds like the API polling limit is having a consequence.

2020 post! What a shyt year that was. I'm assuming you didn't install Tado V3 at that time. Your intention now is to have a single CH zone, and use smart TRVs to impose additional control over some rooms which is quite an effective strategy, as you can take these rooms out of the single heating zone with their own schedules. Your first task is to establish that the three zones can still be actuated separately. Check the individual actions of live on CH1 black, CH2 grey, and HW brown sleeved. With each connected individually to live their respective zone valves only should open. Next you should check the response of the TadoX receiver to its single main stat. When this stat is turned off, the CH relay should be off, no Live on CH NO. If you have already paired the TadoX smart TRVs to the app, you should check that each is configured in its own 'room', with it's own schedule. Check that the zone controller device for the TRVs is the receiver. Any of these TRVs will turn on the CH relay when their schedule is heating, I.e, their schedule temperature is greater than their sensor temperature. this might explain the boiler being on if a TRV is calling via the receiver relay.

It's always a goid idea to get your now two zone system up and running, with just the wireless main stat and the HW timer sending live to their zone valves, whose relays send live to call the boiler. Once you've established this setup is working as it should, introduce the TRVs one by one, giving each a room schedule of its own, but grouping TRVs in the same location, say multiple TRV rads in one room. They can operate within the main stat's 'room' schedule, closing off their individual rooms as the main stat schedule temperature is reached.

Note radiators with no smart TRVs will heat for any call of the boiler. The boiler can be called either by the main stat receiver relay (CH NO), or any TRVs calling the boiler from its own schedule, using the main stat relay as their 'zone controller'. This is how TRVs call the boiler, and asive mentioned, it's likely one of these is keeping your CH NO terminal on the receiver Live, even though the main stat schedule itself is not calling for heat.

If you want to keep two general CH zones, you can replace the old EPH wired Tadox stat for CH2. This will retain your two CH zones, and prevent the open Solo rads downstairs from heating when a call for heat from the upstairs TRVs via the CH2 wired TadoX and its zone valve occurs. With your current wiring Solos will heat for any TRV call, as you've combined the CH1 and CH2 zones.

Care has to be taken with two CH zones assigning which zone controller is chosen as the control device ( boiler switch) for a TRV when you have two. You wouldn't want an upstairs TRV calling the downstairs zone valve, and vice versa.

Ok, a quick journey back to 2020, I've just realised that the post you quoted is not for yourself in 2020, but for @salnado . I was assuming this was you until O noticed your handle was different, so some assumptions I made in my earlier reply are invalid. Most of my other advice stands. If you want to revert to a single CH zone but with some smart TRV control, that'll work. as you can switch of much of the system individually via TRV's. The Solo rads will heat for any schedule, main stat or TRV, that calls the boiler via the zone valve, as these rads hav no means of closing except manually. Thats generally OK, a call for CH heat will always go to the Solo rads, the others with smart TRVs can be dropped in and out with their own schedule.

The situation with the old wall stats is more confusing. If the grey ad black wires that previously switched two seperate CH zones are both off, no 220v live going to them, it doesn't make sense that the boiler is called by either of them the old wall stats merely interrupt this live to the zone valves. They shouldn't be wired to supply a switched live to the zone valve from another source. Perhaps you could post a pic of these two stats, and their wiring, and also the zone valves, as I assumed you have a valved system, with three independent zone valves.

Interesting. A neutraliser tank or blender, then three pumped feeds to your three zones. No zone valves, so you need the Lex controller box to take in the Switched live (SL) from the original timers three zone wires ( via the wall or hw tank stats) and send it to the correct pump. The controller also sends the live to fire the boiler, using relays to do this so any source SL will cause the boiler to fire. Do you have a stove/back boiler source of heat as well as the Vitodens? This is usually the reason for a blender tank like this. I have similar myself, a blender from NRGAwareness, a controller wiringcentre from Homezone, oil boiler and stove inputs, pumped HW and one CH zone output, plus a additional gravity HW circuit to the HW tank from the stove, as a sink for stove heat should there be no electricity for pumping. Ive got just two TRV controlled heating Zones.

Those mechanical stats should do no more than turn off the SL for their respective pumps. There may be an issue with how they were wired, but each should have SL in from the old controller or the new Tado, and they pass this trough to the systemlex controller which selects the correct pump and fires the boiler. The HW Sl similarly usually passes through a tank stat which will power its pump until the tank stat opens when the tank water is hot or else the HW timer slot ends.

You'll have to check and see if one of these pumps is running when the boiler is firing continuously. If they are off, then there's some other issue thats causing the boiler to receive a call from the systemlex box. It has an indicator lamp that lights when a call goes to the boiler, and there should be indicator lights for the three switched relays operated by incoming CH1, CH2 and HW SLs. It requires a bit of mains chasing with a meter or phase tester to find out what's up. I should ask was the Vitodens constant firing occurring while using the EPH? Were there any wiring chages made inside the systemlex box? Check all the connections in the old stats for mains while the Tado is powered off. If any are live, then there's an issue with live where it shouldn't be. Check the HW too, it should be off, as it will fire the boiler if its Sl wire is hot also.

Investigate where the live from CH1 stat that's turning on the boiler is coming from. If the black wire is live, see if the corresponding black wire connected to the Tado is live. Make sure the Tado stat is turned down and no TRVs are active. A single TRV calling for heat will switch the CH telay on, and light up the indicator on the receiver.

To keep CH2 as a separate controllable zone, add an extra wired Tado stat in place of the CH2 stat, and connect the CH2 grey wire to permanent Live in at the Tado receiver.

I have started playing around with Home Assistant and have a good few bits and pieces working (including some TRVs).

However I want to now upgrade the heating controls and think the Drayton Wiser stuff looks good.

I have:

• Bosch Conventional Condensing boiler (Condens 4000)
• Centaurplus C11
• A single heating zone (with Hot Water makes it two channel?)

I think I just need the 1st Generation | Smart Thermostat Kit 2 as I already have some TRVs (and can buy more).

Does anyone know if this is a simple swap of the controller i.e. remove CenatuarPlus11 and drop in the Drayton controller?

Also this is that the kit on Screwfix?