Home heating automation

You'll have a spare output relay on the receiver to control hot water separately if your current setup can manage it, and assuming you have a HW cylinder heated by the boiler. If its just the CH that's being controlled, then dropping the Tado receiver in place of the APT is all that's required. The switch marked Heating may be there to provide permanent power to the boiler.

Great. I suspected it was an old '1½' zone system, aka gravity system. The Tado can be set up in gravity mode to provide HW only timing, and CH timing with HW, but with two different timers. I'll post details which I've saved somewhere.

Here's the installation instructions for the extension kit, gravity mode configuration is in section 6. Theres no wiring diagram shown for this mode, but it's simple. In gravity mode the HW relay Normally open (NO) terminal is closed for Either a HW timed event or a CH timed event. The CH NO terminal closes just for CH events. You connect the HW NO terminal to fire the boiler for either timed schedule, and the CH NO terminal is wired to operate the circulation pump.

https://cdn.brandfolder.io/607DGEMS/as/tqh86npbjjhws5gwkxfncbfh/104172-DIGITAL-WRP01IB01-INSTALLER_MANUAL-TA-UK-00-V2.pdf

Straightforward. HW terminal to fire the boiler and its pump, CH terminal to operate the CH pump. Gravity mode will direct both timers, HW and CH, to close the HW Normally Open Contact, so Hot water is heated for either, as it is now, but the CH Normally open terminal will only close for a CH timed/thermostat event with the Tado stat also calling for heat.

The CH timer is not so much an on off timer as a timed schedule of thermostat settings, say 21° from 8.00 to 10.00, 19° from 10.00 till 13.00, and so on. The schedule is infinitely variable, setting 'Off' is just a case of setting a lower temperature for a give time slot, such as nighttime.

The Electrician should have no issues, he may be familiar with gravity configuration of two zone controllers whose default configuration is two independent outputs, one for HW and one for CH, which is a simpler concept with two zone valves and independent HW and CH events.

You can power up the Tado Thermostat and receiver controller (aka the Extension Kit) before wiring up and bench observe the behaviour of the relays as you set CH on by turning up the stat, or setting the HW timer on. The relays will close as described once you configure it to gravity mode, described in section 6.

I'd assume it achieves power control by duty cycle, modulating the firing on-off in the ratio of 1:9 to limit output and consumption to 10%. These periods could be in seconds, 5 and 45, 20 and 180, or longer. How often you should cycle the ignition and gas valve is up for debate, I'd expect more wear and tear in mechanical components, though they're very robust.

I'm not aware of a boiler that has a variable burn rate, this would be complex to achieve and maintain efficiency, but I'm sure that dual jet gas boilers exist, everything does somewhere.

Boilers with return temperature sensors to limit firing until return cools would be better able to achieve condensing. Slower circulation pump flow is helpful to an extent, allowing hot flow to linger longer in rad panels and HW cylinder coils, to achieve cooler return. Sometimes its like chasing shadows though, you only really save energy by being in a colder house.

Tado announce new X range of smarties. New flavours include.
🔴 Uses new MATTER protocol, future smart things interoperability. Nest interoperability
🔵 New Heat pump bridge to smart connect and control HPs.

🟢 New TRVs with usb charging.

🟡 New dedicated temperature sensor.

🟠 Starter kit bridge and Heatpump bridge are router extenders.

You heard it here first (maybe)
https://www.theverge.com/2024/5/15/24157114/tado-x-matter-thread-smart-heating-europe-price

Many users or many Smart devices? Nest uses Matter, so I guess Nest stat owners now can install TadoX TRV's and link up

I see the new system is incompatible with our existing Tado set-up......

I certainly wouldn't bank on the current Tado V3 being around for long, notwithstanding promises of support from the company. Prices are already dropping in countries where the 'X System' is being launched. 
If I had the current system I'd keep an eye out for discounts and snap up a few items, to keep as spares.

See https://www.tink.at/b/tado

Sadly, I'd assume you're correct

It would be be some kick in the nuts to be forced to upgrade the full set-up. And a serious kick in the wallet too!

I suspect you are spot on in regard to the subscription model. More and more companies are moving this way and are also moving to closed API's to block solutions such as Home Assistant. We may not like it, but it seems inevitable.
One upside is that technology may have a longer lifespan if it earns companies revenue on an ongoing basis.

Doesn't the use of Matter negate the argument of closed APIs?

Turning the gas timing off completely, then slowly introducing it when the electrical heated water runs out might be a better strategy move the gas probe to the tank top outlet and set it relatively high, say 55° if there's no higher cylinder probe spot, it can be clamped to the hw exit pipe.

Hmm. Trying to figure this one out?

This is complex enough and trying to figure out if it's worth it is another thing too. The EV elec rate is just under 8c for a kw. I reckon, allowing for losses, the rate I have for gas (I managed to gey the platinum Flogas rate) is about 10.5c per KW. So only 2.5c cheaper anyway. So maybe this isn't worth it anyway - or maybe it is - and a bit like yourself, it is as much about the challenge of figuring it out!

I'll strap my TH16 probe to the hot water pipe at the top of the cylinder to see how good a reading can be got from it. If I was confident that was accurate i could get a second one, measure temps in the probe pocket and at the top and I guess I could potentially try to figure out a scene in Sonoff based on both measures....

So I asked if the same app is used for X, and can it see both V3 and X configurations. The answer is yes and no, the app can only add an X configured bridge or a V3. Just as you couldn't have two bridges or extension kits on a V2/3 Tado account. You can open a seperate account with a different login, and have two instance of the App, one for X and one for V3. this allows you to control either, but without interoperability between the apps. You could of course have an X zone calling the same boiler as a V3 zone using the standard S plan joint relay switching of the boiler via zone valves, just as you could have Hive downstairs and Tado upstairs with different apps. Heres what they said;

Hello D ,Thank you for contacting us.We’re happy to hear that you’re interested in tado° X! As you may know, tado° X expands smart home climate control to heat pumps as well as boilers and radiators, and uses Matter and Thread technologies to interface with smart home platforms like Alexa, Apple Home or Google Home.However, it’s important to point out that tado° X is not compatible with earlier tado° devices.They use two different technology platforms and can’t be used together on the same account.Technically it’s possible to create two tado° accounts, one to control tado° V3+ devices and one to control tado° X devices within the same home.However, this is not how the products were designed and the two product lines will still not interact with each other, so it's not the best user experience to mix and match.In general, we encourage customers who already own tado° products from the V3+ or earlier lines to keep the setups they have and expand their setups with tado° V3+ products as needed, which we will continue to improve and support.The other option is to switch your tado° setup entirely from a V3+ Home to a tado° X Home.If you are interested in upgrading your whole tado° setup, you can sign up on the waiting list to receive a personalized upgrade offer.

Kind regards,Rastko

On the flip side, these new devices are only targetting heat pumps so far…

Perhaps they wanted to separate the product lines instead of ending up with a confusing product line. Even in Europe gas boilers will be dominant long before many of us are looking to replace our systems so they will need to keep V3 running.

It is silly to not maintain a level of connectivevity for the rad valves though. That lack of "open" connectivity is why I didn't go with Tado personally (plus I got Hive stats + receiver for dirt cheap, €75 all in for two).

Think I'd go with Honeywell in any future upgrade.

I have Hive anyway and messed around with it's Zigbee integration in HA so like yourself I am largely future proofed if they take down the cloud aspect. Only issue is that their implementation of Zigbee for thermostats isn't standard (they have additional criteria needed in the message if the stat is in certain modes to get it to the mode you need / want) so lots of messing and sending custom Zigbee commands instead of just using the set commands.

I also haven't fully integrated the TRVs to call for heat in the Zigbee setup - simply that they close when heat exceeds a value.

But it works, so it will do ha.

Yip. It's exactly one of those green foam covered ones. Any sense on whether it's better to use the metal probe or the temp/humidity sensor to strap on if doing it they way?

Resideo Evohome is still very much under active development; new features are being added, new accessories are being introduced and new commercial partnerships are still being pursued. Yes, it is expensive compared to some products, even more so when bought from Irish suppliers. For me, it has the advantage of working standalone, other than for remote access and weather related functionality. 
Given the range of functionality that Evohome provides it can be complex to install and configure. However it is extremely easy to use on a daily basis, as Wifey would confirm. The complexity of installation depends on whether you are happy with the default settings. If you are it is no more difficult than systems such as Tado.  Bear in mind that with some other systems you don't have the configurable options to begin with. (For example, the default option with Evohome is for alkaline AA batteries to be used in the radiator controllers. A setting has to be changed if Lithium or NiMh batteries are to be used.)
I don't know where Evohome is in its lifecycle but, for sure, it will be replaced eventually. I have already bought a number of spare radiator valves. (The cheaper ones with no local temperature control, for about €40 each.) At some stage I'll see the wall controller on offer and I'll buy a spare one of these and a boiler relay. Then if Honeywell stop support I'll still be ok.

Look, different systems have different cost/benefits. It is up to everyone to do their own analysis as to what best suits their needs. Personally I dislike any system with an avoidable cloud dependency for basic functionality.  In my view it is an unnecessary hostage to fortune. The risks include a vendor going out of business, broadband being unavailable when heating/cooling needed urgently and subscriptions becoming ever more expensive. 

Ah, the clue is in 'Resideo' The evohome is 14 years out, and its a long time ago that I read on some blog the worries of users that it had plateaued. Turns out Honeywell had 'spun it off' to Resideo in 2018 or thereabouts, and they've obviously decided to breath new life into it. The TRVs are a bit vintage looking though.

In fairness Resideo have updated the room thermostats through the years, while maintaining full backwards compatibility. The new DT4R Thermostats are really nice. I'm not worried about the aesthetics of the TRV's, only their reliability. They have a five year guarantee and exercise the water valve at least every 2 weeks to prevent sticking. Hopefully both will last for many years!

Anyway, the evohome TRV's with a display are complete overkill. In practice we either use a room wall thermostat, or the wall controller, to adjust room temperatures. The HR91EE units are far cheaper and also have an open window contact. This can be used with a window sendor to turn off heating as an alternative to detecting sudden room temperature drops. I wish I had known about them before I bought the HR92's

I've got it working well enough to turn the system on in a schedule and override that schedule (set temp higher than current set value) and then turn it off from HA and Google Home which is 99% of what I actually need. Could talk all day about it ha.

I can always move back to Hive's own integration, app etc. when I need to.

This was to prove when the internet is down or they scrap it I can still keep some control and it's been fine so I never bothered reverting back.

I wouldn't reccomend it for 99% of people haha.

A 16A shelly plus should be sufficient for an immersion rated up to 3kw, 3.5 tops

thanks both. have used few shelly but never used sonoff. will check both and buy.

It really depends on what is there already? For example you might need new TRV valves on your rads to take the Tados? Is there an existing thermostat in place?

By the way. If you do already have a thermostat in place, then, to be blunt, you might as well bend over and be done with it in terms of being screwed with the quote. With deezel here - he is the go to man on these things by the way! - but a straight swop of thermostats is a 10 minute DIY job....