Hot water monitoring & Tado hot water tank thermostat

Hi, I'd like to be able to monitor our hot water, so I can see when the hot water is requesting heat from the boiler and ideally see the temp of our cylinder tanked hot water. The app shows simply off and on.

We have the Extension Kit controlling our heating and hot water. There is no way of telling when the hot water has called for heat. The app doesn't show anything as far as I can see other than off or on.

I've seen other people have used a sonoff device in addition to monitor temps, and even to control the on off via the extension kit.
It would be good to use a Tado cylinder tank thermostat instead of needing a 3rd party piece of hardware and software to see the above.

Are Tado considering a tank thermostat or adding more days to the app in regards to hot water heating?
34 votes

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  • XKRMonkey

    Hi @Ben_UK

    You're right about needing a Tado-integrated hot water temperature sensor, actually as far as I can see this is a gap for pretty much all of the domestic CH control players, and it's not clear to me why.

    In the absence of anything official, and because I have a lot of other Smart tech in the house, I have started to use these:

    The Ewelink app allows you to create behaviours that are operated based on time or temperature. It's simple to wire it to a standard solenoid valve or you could use the TH16 version to operate an immersion heater.

    I have these monitoring both my water stores, and operating the heating for one of them (I use the Tado water heating for the other store at present). The issue is that you either rely on the tank thermostat alone to drop the demand to the solenoid valve, or you use the sensor to more accurately operate the water heating.

    I'm about to install some additional sensors just to monitor the feed and return pipe temperatures, in order to better understand the boiler performance.

  • Ben_UK
    Thank you, the th10 does look good and looks a good workaround. I was hoping I might get a reply from Tado, maybe @Jurian as seemingly the only Tado representative.. and was hoping to learn this is something they are looking at.. but will look into the th10 too.
    Thanks again
  • Montage

    I agree and I’m sure I said the same in the last similar thread.

    I use DS18B20s attached to an ESP8266. You can push the values to MQTT or whatever you have at home. Currently I only watch flow and return.

  • Jurian
    Jurian | Admin
    edited November 2021

    Hi all,

    At the moment, we believe the market for this is product too small and the DIY installation procedure too difficult for mass market adoption. Instead, tado can already control system boilers with hot water tanks using these two digital controllers

    • Vaillant VR65 (Not VR66) using Vaillant EBUS
    • Glow Worm Smart Wiring Centre 1 (also using the Vaillant EBUS digital protocol, not the Smart Wiring Centre 2, that is incompatible)

    Now that the UK is finally taking the adoption of digital heating control more serious, we expect more of these controllers to come to the market, and because we are already compatible with nearly all digital control interfaces we should be ready to also do hot water temperature control for digital system boilers. (As we already have compatibility for digital combi-boilers).

    For our power users, who are not on Glow Worm or Vaillant, the best option is to look at 3rd party solutions if you really want to monitor/control the hot water tank temperature.

  • Ben_UK
    Ben_UK ✭✭
    edited February 2021

    Thanks for the reply, it's a shame that's Tado's view.

    I can't see a cylinder tank thermostat as being a particularly hard diy install, no trickier than fitting the extension kit.
    I do imagine the percentage of users with combi-boilers with no hot water tank is large so I guess it's mostly a production / profit thing?

    In the meantime is there no way of displaying more accessible data for the hot water?
    I cannot even see if it's call for heat is on / off or for how long it has been on during the day (like I can either the radiators).
    I do know that since moving from our original 'dumb' programmer to using Tado we have to have the hot water switched on all day otherwise the water is not sufficiently hot enough for us all to shower. I'm not certain that our hot water is calling for heat as often as it should be.. and there is no way to monitor within the app that I can see.

    Additionally we are looking at thermal solar, so even if we were to change our existing boiler to a combi we would still have a hot water tank. Is it possible the rise of solar use may increase the desire for Tado users to want to monitor their hot water in a similar way to the heating?

  • Jurian

    Please note that the whole concept of a programmer (S-Play / Y-Plan) is unique to the UK (maybe Ireland). This vastly reduces the market already.

    Take into account the fact that many people have a more simple combi-boiler.

    And then take into account that the vast majority of people would not want to spend extra money just to do a bit of monitoring of the hot water tank and you could understand that bringing out a special set of hardware for this niche is difficult.

    @Ben_UK I believe you have an underlying issue with your hot water system. Normally a few hours per day should be enough to have enough hot water in the tank for the whole family. I would do some manual investigation to see why this is. As soon as it is working again, the need for the monitoring goes away also. (still a nice to have)

  • Ben_UK

    We had no issue with the hot water before fitting the Tado Extension Kit. Our previous programmer set the hot water to heat on schedule, since fitting the extension kit we have needed to have it on 24/7

    I did run some checks but not thorough. I did email both support and installation but have never had a reply on the matter.
    An example that concerns me is; with our hot water on if I turn up the thermostat on the tank from say, 60°c to 75°c nothing happens. If I then switch the hot water off within the app and then back on again the boiler kicks in and the hot water starts to heat. This doesn't seem quite right to me and may explain why it needs to be on 24/7 ??

    I'm pleased to say fortunately the boiler is not on permanently so something is working correctly(ish).
  • Montage

    Sounds like a fault that needs troubleshooting.

  • Ben_UK

    I have emailed support several times but they simply have not replied regarding the above issue.
  • Montage

    I wouldn’t expect them to be helpful. It needs troubleshooting on site.

  • Jurian

    @Ben_UK I agree with @Montage

    We will not be able to help.

    Tado only switches a relay on/off to turn on/off the boiler to produce hot water.

    You need to troubleshoot the tank, the 3 port valve, the boiler tank thermostat.

    This is something that can only be done when you are actually on site.

    Feel free to get any boiler engineer to have a look, he should just take the tado from the wall and manually move some of the wires to bypass and exclude tado. That way he can try to find the issue.

  • XKRMonkey

    @Jurian thanks for responding, and I think your second explanation about market size for certain features is helpful in some respects for context (not just applicable to this thread too).

    I would phrase this in a slightly different way, which may be something that can be considered by Tado:

    The TH10 device I mention above is a plug-in external temperature probe and a device capable of reading the temperature probe and switching a live feed. The cost of the whole kit is around £18, you can buy the probe on it's own for £3-£4, and the device is £15 or so without the probe. Clearly, the component parts (A2D chips and supporting physical seocket) required to read the probe (which seems to be a generic part with a jack plug connection) are a few $$$ or less from a production cost perspective.

    Would it not then perhaps make sense for Tado to include the temperature reading function (hardware and software) and a jack plug on the receiver so that the end-user could choose to plug in a temperature probe and read their tank temperature and display it in the app ? From there it's a short step to making the hot water schedule capable of using that temperature too, allowing scheduling that either maintains water at a preferred temperature, or simply shuts off demand once the temperature is reached (modern well-insulated hot water stores lose temperature much more slowly than rooms do unless water is being drawn down).

    Even for markets outside the UK, a lot of Smart tech such as Tado is as much about comfort and convenience as it is about saving money or the planet generally. Knowing that there is plenty of hot water or no hot water before you jump into the shower is a real positive, especially if you live in a house with several others. Being able to specifically heat the water and run a maintenance program for it at peak usage times (like morning or evening showering) is a convenience that may have a smaller market than regions with shared domestic heating services where the heat is "free" or "all you can eat" rather than the UK model, but even in that situation, being confident of the situation before getting an accidental cold shower has merit.

    For the UK market, there is a secondary health and safety consideration that may add value to the feature. Defending domestic hot water systems from legionnaires bacteria requires water stores to be able to heat to more than 50^ reliably, which is at the limits of "scalding" for most people. Being able to check tank temperature is routinely exceeding that level is a secondary but real benefit.

  • Jurian

    @XKRMonkey Thanks for those insights.

    If you have more information about those probes, please post them here, also put some pictures on how those things would be installed etc..

    We have UK specific hardware (no where else does a Y-Plan or S-Plan dual relay system exist) and if we ever do a new hardware design, this could actually be a great feature to distinguish ourselves from our main competition. I am not making any promises other than

    If you and/or the community forum could somehow clearly document the required hardware, and the interface, I will forward this to our product managers.

    Feel free to do this in a PDF form for easier layout.

  • XKRMonkey

    I'll find a little time over the weekend to respond fully, thanks @Jurian

  • XKRMonkey

    @Ben_UK I just re-read your post about your hot water problems, here are a few thoughts from my experience that may help you fix your issues.

    I hadn't noticed that you'd switched from a time-clock system to Tado, so here's a few checks you could do yourself fairly easily. Start by getting yourself a simple mains tester (I prefer one of the non-contact types like this because you can check part-way along a cable as well as at an exposed point).

    1. Check that you included the bridging link between your permanent live feed and the common HW connector on the Tado receiver backplate. You should have a link from the LIVE (Connection 2 counting from the left of the back plate) to CH COM (Connection 3 from the left) and HW COM (Connection 6 from the left). Without these no demand will be received by the boiler at all.
    2. Check that your CH connection to the Boiler is from Connector 5 and your HW is from Connector 8. These are more complicated because there are several options here. Typically CH will be connected directly to the boiler demand feed, but HW is likely to connect to the solenoid valve that operates you hot water tank heating loop. If that is the case, then you probably have a secondary wiring block close to the receiver where the onward connections to your heating system are made, and in my experience "professional electricians" don't always take the time to make this easy for an amateur to follow. This is why the contactless mains tester is useful.

    Start by turning on your boiler by raising the demand temperature for one of your rooms so that the app says it's heating. If you now use the testing want, you should get an indicator from the tester on the cable that connects to the boiler. If your boiler is close to your receiver (mine is in the loft), then you may see the boiler fire up when you make the demand which proves that the CH wiring is correct.

    Now turn off all the heating, and make sure that the boiler shuts down again for you.

    Now use the app to turn on the HW. If the connections are correct, then the boiler should start up again. If it doesn't, then you need to start by checking that the demand from Connection 8 is giving an indication using the tester. If you are seeing the demand from the receiver on the tester, then you have a wiring problem to the solenoid, or in the way that the solenoid passes the demand on to the boiler once it activates and opens. With HW, the demand from the receiver does NOT go straight to the boiler, it goes straight to the solenoid valve, and the solenoid actuator has a switch that only connects the demand to the boiler if the valve opens successfully (so that the boiler doesn't fire if there is nowhere for the heat to go). When properly wired through a modern indirect cylinder, there will also be a tank thermostat (generally not very sophisticated) that will be open above a temperature that you can set for yourself (probably around the 55-60^C mark. When correctly wired, the HW demand to the boiler passes through the solenoid switch ("Yes, the valve has opened") and the tank thermostat ("Yes, the water needs to be heated") in order to make the boiler start to run to heat the HW.

    This means that there are two places where incorrect wiring could impact the HW working properly, even if the receiver demand is correctly activated (the solenoid wiring and the tank thermostat wiring). Separately, the tank thermostat could just be set too low (so the demand is withdrawn early because the tank is "at temperature").

    Troubleshooting the whole HW wiring may be complicated if you don't have easy access to either the solenoid valve wiring point or the thermostat wiring point. However, if you had a simpler timeclock system for the HW that worked OK, and you literally took the HW connection from that and connected it to Connection 8 on the Tado Receiver, then my money would be on the link between Connector 2 and Connector 6 being missing or not properly connected. Tado do provide two pieces of wire in the kit for exactly the purpose of connecting Connnector 2 -> Connector 3 -> Connector 6 (and the poorly named "Manual for Professional Installers" shows clearly how the backplate should be wired).

    I hope this helps you isolate your problem and fix it, or at least call in a professional electrician to complete the troubleshooting if you've checked the basics and it all looks OK.

  • XKRMonkey

    One other thing to add on the general topic of Hot Water:

    When you turn on the HW demand (manually or by a schedule), you are verly likely to make a massive impact to the CH performance. This is for a couple of reasons:

    1. Your flow and return heating water circuit is probably all on 22mm copper (or plastic), but each radiator drop will be 15mm or 10mm and flow through each radiator is restricted (balanced) by the lockshield valve, regardless of how open the TRV/SRV actually is. Your HW heating water circuit through the hot tank heating coil is probably 22mm all the way from the boiler, through the solenoid, heating coil and back to the boiler with nothing to choke or resist the flow. When you turn on the HW heating (open the HW solenoid) then almost all the boiler feed water will prefer to run through your HW tank coil, not through your more resistive radiator circuits. This means that the radiators almost immediately start to cool and will continue to do so as long as you're heating the water tank.
    2. Your hot water tank is an energy store. The bigger it is, the more energy is needed to heat it through 1^C. When the tank is cool or cold, the boiler feed water may enter the coil at 70^C but the tank will suck that heat out and the exit from the tank coil can be massively lower in temperature on the return side, meaning the boiler needs to burn a lot of gas to reheat the circulating water feed whilst the tank heats up.

    Basically, this means that the better insulated your hot tank, and the pipework around it and running to/from the boiler (to all of your radiators too) then the better, from an economy and a heating performance perspective. It also means that the way you programme your water heating can make a significant difference to your comfort generally, and to your perception of the performance of the system.

    I have two water stores, 120L and 150L, so around 275L all told. The smaller tank feeds the kitchen and downstairs shower/bathroom. We don't use the shower much, but obviously during the day, we use the bathroom regularly and we run the kitchen sink. I reheat this tank for short periods through the day, to maintain a tank temperature of between 60^C and 65^C. Maintaining a higher temperature means that the boiler isn't doing too much work, and I am only needing to raise a comparatively small tank volume a few degrees in each cycle. 15 minute dips in the ability of the CH to maintain isn't too onerous or noticeable most days.

    The 150L tank feeds the utility room, the house and en-suite bathrooms, which also have showers. As a family we mostly shower in the morning when we get up or in the evening after work. The tank is heated to full temperature (around 65^C) in the small hours when a prolonged period of hard heating isn't impacting the house comfort (typically between 0300hrs and 0500hrs). The tank gets well used when we get up and cools significantly first thing in the morning, but I reheat it in bursts of 10 minutes after 0900hrs after the heating has reached proper temperature and has started maintaining the room comfort. This moves the tank temperature back to usable by early evening and I don't care if it gets heavily used because overnight it'll get it heated again.

    Since both tanks are new and well insulated, they don't lose temperature too quickly, so the intermittent heating doesn't really cost much more than a single burst, but my comfort levels overall are much better. Using two separate smaller tanks allows me to manage the HW demands of the house more efficiently.

    I hope this helps others to understand the impact of HW heating and one method of mitigating some of the impact and reducing the costs.

  • Rob_Cole

    Firstly, I'd like to say I'm really happy with my Tado system, it works brilliantly at what it does and was really straightforward to install.

    I'm very keen to have the added connectivity discussed in this thread. I'd really value knowing how hot the tank water is (the cylinder supplies water for heating (directly) and hot water (via a coil) and is heated by a gas boiler (via a coil) as well as surplus generated solar energy when the sun shines). Knowing the tank temperature would allow us to be smarter with what temperature is needed to heat the house and provide hot water under different scenarios. The ability to switch hot water on with the heating if temperature is too low for example would be very valuable. Also being able to link outside weather and temperatures into how much heating is done for the tank, e.g. sun is shining, temperature is above x, lower tank heating threshold to y.

    I think as time goes on more and more people will want more functionality and interconnectivity out of these systems.

  • Hi Tado team. Fully support the idea of a tank thermostat. Seems crazy to only run hot water on time base, would prefer temperature. Also good to track temperature through day. Probe idea sounds good. I have just added some tado room thermostats linked with radiator valves would be good to add this unit for water tank. Anyone with oil heating system will have hot water tanks.
  • Ben_UK
    @Jurian how about Tado employs @XKRMonkey !?!!??
  • Brain_k

    Hi all,

    I have noticed a similar issue with my installation and during my search, I found this topic that I think it's related to the problem.

    I have an S-Plan installation, tado controller for hot water and also controlling 2 zones. My boiler has entered in safe mode twice already because of the hot water feature. I have the hot water scheduled to come up twice a day for 1.5 hours. On both times the boiler entered in safe mode was when the hot water schedule was ON.

    So, in my case, my water tank has one of those temp sensors that you put the temperature you want for the water and if the tank reaches that temperature it shuts the valve. And I think this is the issue that I faced on these 2 occasions, the hot water kicked in on the schedule, during that schedule the water reached the temperature and the sensor shut down the hot water valve, but Tado never knows about that so the boiler continues to run, since during that time no other valves opened the boiler detects that and that's why boiler stopped working and showing flashing lights (safe mode).

    Is this the normal behaviour, or am I missing something here?

  • XKRMonkey

    @Brain_k yes, Inthink this is to be expected the way you describe your setup.

    You really need to have at least one path that never shuts - for me this is the towel rails in the bathrooms, which are warmed any time the boiler is run - effectively a lot of the day. These brooms have no schedule to apply, so warm anytime you need to visit is the winner. This also gives the boiler some way to circulate if it’s running and nothing else needs the heat.

    But, I have a question:

    is your 1.5 hours really the right length of time to heat the water ? That sounds like a long time - my 150L tank heats from dead cold in around 45 minutes, but using a live feedback loop (via my Sonoff controllers) I see short heating cycles of 10-15 minute top-ups two or three times a day depending on water usage.

    This approach is clearly more efficient, but importantly, these top ups often occur when the boiler is already hot, and so I am just redirecting the heat briefly. When I used your approach, heating a large cold water store, I saw real impact on room temperature maintenance because the water stores have 22mm feeds, easier for hot water to run through 22mm loops, rather than 10mm radiator loops, even if they are open. It effectively extended morning house heat cycles by an hour or more. Until Tado provide a useful method to link water heating controls based on live temperature readings, I shall stick to the Sonoff solution.

  • I do have a thermostat displaying my hot water temperature, right next to my Tado controller. We have water solar panel controller. It would be great if the wire used to sense the water temperate of the boiler in the solar panel controller could also be used and read by the Tado controller, unfortunately the solar panel controller does not have an app.. its to old!

  • Gabs
    edited December 2021
    @Brain_k : I was worried that tado controller may keep the boiler firing indefinitely during the "HW on" schedule. So I've tested that: while all CH was off but with HW on and therefore the boiler running, I've dialed down the thermostat on my hot water cylinder, which is wired to the motorized Honeywell valve on the HW circuit. The boiler shuts itself down a couple of minutes after the dial in a neat way ( but the HW l.e.d. light remains on on the tado wireless receiver)
    Fyi: I have an Y plan.
    Regarding your question: is it normal that tado doesn't know the HW temp? I guess that how my prev programmable centre worked as well: a couple of times a day, it would get a 2h window to warm up the HW. The rest was handled by the valves on the circuit talking back to the boiler.
  • jelly

    I am in agreement with XKRMonkey and Ben_UK, it would be great to control the temperature of the hot water tank. It does seem very inefficient heating the hot water to the stat temperature if you only want to wash your hands. May be my heating system is not your average, with a solar panel and wood burning stove supplying heat to the heat store, but I know many more people with this type of heating than AC. If I know that I’m going it get the hot water heated from the solar panel during the day, I don’t want the boiler coming on, and the same goes for at night with the wood burner. So being able to set the lowest temperature of the heat store before the boiler comes on is a big saving.

    As said the easy work around is to use a Sonoff TH16, and it is probably cheaper, but this means you need two apps and it does make the Tado not quite as smart. My Tado app is telling me I have saved 100% with Tado this month, but sadly my smart meter does lie!

    May be it just costs too much to add this, but could the AC controller be modified to perform this function.

  • Catarina_Scotland
    edited October 2022
    Hi, I’m in agreement that controlling the temperature of hot water tank would be really helpful. Before we put the central heating on, I’d just set the timer to as short a time as possible, but having the CH on has thrown this all off. Testing out different lengths of times to have the HW on seems a primitive approach. I will check out the Sonoff kit others are recommending.

    Apart from this I am really appreciating the Tado, really good to be able to see which rooms need the most heating and to be able to control the temperature so sensitively.
  • st2
    I’d just like to add that regardless of market size, for anyone with a hot water tank, having a simple on/off seems to entirely defeat the point of tado. We’re missing all feedback on how hot the water actually is. Imagine being able to set a high temperature temporarily for a nice bath, but keep it lower during the day (just for dishes etc). Or even reducing temperature whilst on holiday to a safe level, rather than just off for 2 weeks.

    It sounds like integrating with another provider is the way to go here.
  • luteijn
    An easy way to integrate 3rd party sensor data for 'niches tado won't develop for' in most cases wil improve sales, only in a few cases would pesky DIYers stop using your service and leverage this way of input to bypass using tado gear.
  • dws1900

    I fail to see why this is so complex.

    The tank thermostat is only the same as the wall thermostat in its operation, with radio connectivity to the tado controller. Simply put strapping a wall thermostat to the tank would probably work (but not advised)

    The electronics would be identical with the exception of requiring a thermal probe to the side of the tank.

    I am sure there will be disagreement, please tell me why this would not work.