Explanation of the 3 Wavy Lines....???

Hi everyone,

Earlier today I raised a question with Tado Support....

I have asked them to give me a 'definitive' explanation of Exactly what is happening when any of the 3 wavy lines are displayed.,,,,,,,,,ie

1 wavy line means.......???

2 wavy lines means.....???

3 wavy lines means.....???

There are actually a few possible explanations (and we 'the users') will have our own idea of what we think the Tado system is actually doing when we have a "wavy line" display.

Please feel free to 'add' your interpretation of what you think each of the 3 wavy lines means to you.

Best Answers

  • Rob2
    Rob2 ✭✭✭
    Answer ✓

    Those are a crude indication of the modulation level. 1 wave = low 3 waves = high.

    When you don't have modulation (relay control on the COM/NO/NC connections) there is no meaning.

  • GrayDav4276
    GrayDav4276 ✭✭✭
    Answer ✓

    I actually hope that you're correct in regards to the radiator valve opening level and the 'number' of "wavy lines" displayed in the App etc.
    As I said in my first post, I have asked Tado Support for a full explanation......so maybe soon (uncontrolled laughter) they'll reply.
    I will post their explanation......when/if I receive it.
  • NeeWii
    Answer ✓
    Going against some of the comments above, I don’t think tado is capable of “partially” opening or closing a valve. It’s either entirely closed or entirely open.
  • GrayDav4276
    GrayDav4276 ✭✭✭
    Answer ✓

    @Rob2 @samd @NeeWii @GrilledCheese

    ## UPDATE ##

    Hi Everyone,

    I have now had the "definite" response from Tado Support regarding how the Tado SRT's operate the TRV's on our radiators......

    The SRT only "fully opens" or "fully closes" the TRV valve. It does not "partially open" the valve if 1 Wavy Line is showing........or........"increase opening level" for 2 or 3 Wavy Lines

    The Wavy Lines are an "illustration" of the level of "demand" applied to your boiler......So

    1 Wavy Line = Light Demand (which could be just the pump operating and no boiler firing)

    2 Wavy Lines = Medium Demand

    3 Wavy Lines = High Demand

    Also.......if the difference in temperature demand is high......ie more than 1 degree then the boiler demand will be Medium or High (dependant on the size of temperature differential.....2 or more degrees) So I 'step' my change in temperature (in the App etc) in in 1 degree increments (SRT) and 0.3 degrees (Wireless Thermostat).......this reduces the "High Demand" on my boiler (modulating boiler)

    It was a bit of a "faff" to change my schedules......but I feel that it was worth it.

    There will be people who don't like to have this level of interaction with their Smart CH system, and so this will not be for them......and I appreciate that. There will also be people who may have already known all this.......respect.

    But there will be many people who didn't understand how their system "actually" works, and have had a "skewed" perception of what is/was happening.

    And so if I've helped anyone.......I'm happy .......if I've annoyed anyone, then at least you've read this post.

  • GrayDav4276
    GrayDav4276 ✭✭✭
    Answer ✓

    Hi @samd

    Not all boilers are Modulating Boilers........

    My system is a Wireless system, so I'm not up to speed on a "Wired" system tbh.....but my assumption would be that if your boiler is a Modulating Boiler then I would expect that a Wired Thermostat 'should' achieve this.

    Sorry that my answer is a bit "wooly" but it's the best I can do.......however I suspect that @GrilledCheese2 will probably have a greater depth of knowledge on this than I do.

  • GrilledCheese2
    GrilledCheese2 ✭✭✭
    Answer ✓

    Boiler output modulation is the ability for a boiler to turn down its output. If you have a 20kw boiler, but the home only requires 10kw of heat for the next hour, rather than outputting 20kw for 5 minutes then resting for 5 minutes repeatedly (short cycling), the boiler will simply turn down its flame by 50%. The boiler achieves modulation by measuring the water flow temperature and adjusting the size of the gas flame to keep the flow temperature constant. The fewer stops/starts the greater the boiler efficiency and the less strain on all system components. The room thermostat has no influence over this type of modulation.

    Modulation of the boiler flow temperature is used for load compensation. Load compensation comes in two forms: weather and room. When referring to room compensation the room thermostat will modulate the boiler flow temperature to achieve the required indoor temperature without overshooting. When the room is cold, the water temperature going to your radiators will be high, but as the room warms up less heat is required, so the thermostat gradually reduces the water flow temperature going to the radiators. The water temperature might start at 70°C but reduce to 50°C as the room temperature reaches its target.

    Weather compensation is achieved with an outdoor thermostat that will modulate the boiler flow temperature depending on the temperature outside. So on a cold winter’s night the boiler flow temperature might start at 75°C. During autumn and spring the boiler flow temperature might start at 60°C because the heating load is a lot less due to less heat loss.

    Modulation of the boiler flow temperature cannot be achieved using relay control. It needs a communication bus protocol such as open therm. The benefit of a lower flow temperature is the boiler will condense more, making it more efficient.

    Modern boilers should be capable of all of the above, it just depends on how they are wired up.


  • Hi @Rob2,
    My boiler is a 'modulating' boiler.....so what you're saying is 1 line means a 'lightly' firing boiler....and 3 lines means a 'heavily' firing boiler...corret ?? 🤔

    So....does this have any effect on how the SRT opens the actual radiator valve, or is the amount of valve opening designated by the temperature set in the schedule (or manually).
    The reason I ask is because I'm not sure that the Tado SRT's set the 'opening' radiator valve in the same way as a normal 'dumb' TRV does.
    In other words the 'dumb' TRV will only 'slightly' open the radiator valve.....whereas I suspect that the TADO SRT fully opens the valve to allow new hot water into the radiator.....and closes completely when the set temperature is achieved......in other words the SRT is either fully open or fully closed.

    What is your perception of how the SRT opens and closes the valve.

    Has anyone else got any ideas ?? 🤔
  • samd
    samd ✭✭✭

    @GrayDav4276 I think that when, say, on one bar, my boiler pump will always be working but not necessarily the boiler firing and when on one bar the valve will be nearly closed.

  • Hi @samd,

    I agree with your ascertion regarding the pump/boiler operation as my boiler is a modulating boiler. ✅

    However I still need convincing regarding the valve positioning......I still think that the SRT simply "opens and closes" the valve body.....ie fully open or fully closed.

    Can anyone shed any light on this part of my query ?? 🤔
  • samd
    samd ✭✭✭

    @GrayDav4276 I suppose that because 1 rad can be needing 3 bars and another just the one, the boiler itself cannot be reacting differently to the two rads. In that scenario it's pumping out max but the rad on 1 bar is nearly closed.

  • @GrayDav4276 this partly answers your question.

    For a smart thermostat operating in relay mode the percentage represents the amount of time the relay is closed. For TRVs and Opentherm mode it will be a different method of control.

  • Hi @NeeWii,

    That's exactly what I think.....I think that the temperature sensor simply opens or closes the valve by switching the motor supply from +ve to - ve and vice versa causing the motor to travel it's "end stop".
    I will check out the response from Tado, and how they 'word' the explanation.
  • GrayDav4276
    GrayDav4276 ✭✭✭
    edited January 2021
    Raised this question with Tado Support on 8th Jan.....still no response by 14th Jan
    It's still showing as "not seen yet"
  • samd
    samd ✭✭✭

    @GrayDav4276 Hi and thanks for that. You (and tado) got there in the end. Question please. Can a boiler modulate when connected to the wall stat by 2 wires only?

  • Hi @GrayDav4276 & @samd when you say modulation, are you referring to boiler output modulation or boiler flow temperature modulation? I ask because lot of people confuse the two.

  • samd
    samd ✭✭✭

    @GrayDav4276 & @GrilledCheese2. Sorry to labour a point but mine is Worcester Greenstar and is a modulting boiler according to the handbook but something I read a couple of weeks ago seemed to suggest more than 2 wires are required for such a boiler to operate properly. I am lost on the 2 aspects of modulation.

  • samd
    samd ✭✭✭

    @GrilledCheese2 Many thanks for that. Extremely useful but might (will) need reading more than once!

  • @samd I'm with you there, modulation would require more than a simple on/off relay. Can @Tado tell us if the Tado stat can send modulation instructions? Or is the wavy demand simply a visual guide and your letting the boiler auto modulate?