Additional weather compensation probe

I live in a 19th-century granite building. Heating system - Alpha Innovations e-tec 33 boiler is managed by Tado. Does it make sense to install an additional weather compensation probe 3.022383 as an additional measuring device? 

Thank you in advance for your suggestions


Best Answers

  • Vertigo
    Vertigo ✭✭✭
    Answer ✓

    Thats a bit nonsensical. First of all, its unlikely a self mounted probe on a wall will give a more accurate measurement than what "the internet" will give you, as those measurement come from calibrated and properly shielded weather stations and there are plenty of those,certainly more than just one for Aberdeenshire:

    Tado have your address and probably GPS coordinates, they should know the temp where you live better than you would with your own thermometer.

    Secondly, even if there was a 5C difference between what tado is told by their meteo service and what is actually true (which wont happen), check out your own graphs to see how little difference that makes, keeping in mind you need to adjust the value, so pick a curve that lets you warm the house; so even if the measurement is incorrect, the point is that you pick a low enough setting that still allows you to warm the house and the boiler will vary that with outside temp.. The efficiency is having a low boiler temp, that doesnt really depend on the absolute accuracy of the sensed outside temperature, you just need a ballpark figure. The more important value is the one you would pick, which of those lines.

    Lastly, if tado do it right, which in fairness, I kinda doubt, they could even ignore outside temperature and simply adjust water temperature on the fly since they have all the data needed to optimize the boiler for your specific house and circumstances: they have logs and can see exactly how fast or slow each room heats with what water temp, and they can see when what temp is requested in the future, things your boiler doesnt know.


  • Hello Alinoe,

    Our systems won't be compatible with any external sensor.

    For the external weather we have already included information that comes from a 3rd party service. This information service covers every area with several stations. However, if you find you'r general area information is not fitting the needs of the house, you may find a possibility of integrating those 3rd party sensors through any of our smart home integrations.

    Best regards,


  • Hi Tom,

    You mean a weather compensation probe connected to the boiler itself?

    If so, I asked a similar question here but never got an answer.

    I ended up installing one - in my case it just adjusts the heating circuit temperature (maximum power) based on the outside temperature so I figured it can do any harm.

    What I would like to know is whether Tado algorithms:

    1. read and use the external temperature measured by the probe (OpenTherm should support this) ;
    2. adapt to the changing boiler maximum power.



  • Hello,

    I don't know that either. The problem is whether the system will not be disturbed by an external probe on the boiler. Maybe it is better to leave it as it is. My building is a 19th century granite structure and is rather poorly insulated. That is why I try to squeeze as much as possible out of it. In the e-mail from Germán above, writes that the tado system does not work with external probes so in this case I will give up this option. I suspect that in case of any doubts, the "heating curve" table should be used manually.



  • Hi,

    I think @Germán is talking about something else entirely. Like integrating another external device (e.g. Netatmo) or weather service that provides external temperature readings.

    The question on the other hand is referring to a feature of some modulating boilers - adjusting the heating curve based on probe measured external temperature.

    @Germán could you please help us with an answer on this?

    Thank you,


  • From my boiler's manual:

    VT: Flow temperature

    AT: External temperature

  • @andreig1978 Maybe you're right. I was interested in using a typical external sensor used and branded by the manufacturer of my Alpha Innovations boiler. I am not interested in other external devices.

  • andreig1978
    andreig1978 ✭✭✭
    edited November 2019

    And from the OpenTherm spec, the two values seem to be covered by:

    5.3.4 Class 4 : Sensor and Informational Data

    25 R - Boiler water temp. f8.8 -40..127 Flow water temperature from boiler (°C)

    27 R - Outside temperature f8.8 -40..127 Outside air temperature (°C)

    (where the boiler adjusts 25 based on 27)

  • 27 R - Outside temperature f8.8 -40..127 Outside air temperature (°C)

    This interests me most in a local matter not within the reach of the entire area. Such a survey would help me to adapt to the conditions in my particular location and not in the entire Aberdeenshire area.

  • Hello, just to clarify:

    I was referring to the fact that tadoº can't integrate any external input itself. However, if the boiler has another sensor while using tadoº only as a temperature measurement control (some digital boilers offer this option), we wouldn't interfere with them.

    I hope this is clearer now.



  • Thank you for the discussion and the hints. I gave up the idea. I'm just staying with TADO :)



  • I wanted to clarify, where @Vertigo mentions that "Tado have your address and probably GPS coordinates, they should know the temp where you live better than you would with your own thermometer." would my Tado smart thermostat always use outside temperature when controlling my boiler, or is this only a feature of the subscription product that you have to pay for per month/annually?

  • Well, I'm terribly late to this, but if any of those who raised queries initially and bought tado's nonsensical response touting internet-based weather forecasting would still like to gain more efficiency, I can confirm that boiler weather compensation paired with tado running in RELAY (on/off) mode absolutely works. It won't work with tado using load compensation (OpenTherm or another), as tado will override the boiler.

    I've been running this set up for 10 years. Extremely efficient.

  • @DM932187 I just got to know more about the topic was thinking exactly the same, connected in relay mode tado just calls for heat ie. doesn't interfere with the boiler flow temps. Would it make more sense to get EU Tado and connect with OT or just stay with relay and get the weather compensation probe fitted directly to the boiler?
  • A weather compensation system with Tado would probably be the most efficient, but a lot depends on other factors like boiler size, rad size, insulation level.
  • As @johnnyp78 says, there are several factors to consider, but unless you live in a pretty new property with high levels of insulation, you'll probably be happier with weather comp and relay

    It'll take some getting used to, as tado will essentially become your central temperature limiter. If you have smart TRVs, you'll have to start using them more like dumb TRVs, albeit you can use some scheduling through tado. You'll be aiming to get the flow temperature as low as possible without compromising the target room temperature. This will maximise the boiler condensation (I'm assuming you have a gas mod/con) and potentially get you into the upper 90% efficiencies.

    The key point with weather comp is that having lowered the flow temp right down, you won't be able to have deep temperature setbacks (max 4C reduction) - the house won't heat back up again (unless you have WC with parallel shifting) - or more than 2-3C temperature differential between rooms (using TRVs). Avoid micro-zoning, and really just have room temp differences between floors (e.g. 19/20 on living floor and 16/17 in bedrooms).

    If your boiler has advanced weather comp (fully adjustable curve and parallel shifting), it's a no brainer. If basic (like mine), still probably better. Load compensation is really for boilers that don't have weather comp.

    Very good info on, if you've not seen it already.

  • Thanks a lot for the explanation, sounds like I would benefit more from sticking with relay and adding the WC probe. My boiler is the same as the OP (oversized for my needs currently so definitely need to modulate) and my house is old (70s). The WC options for the Alpha boiler appear to be basic as it only allows a selection from 9 possible curves.

    I've been watching heatgeek on YouTube actually, great stuff!

    Thanks again!