Managing hot water with Combi on Opentherm - Using energy?

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Floob
Floob ✭
in General Questions & Topics

In order for the hot water temperature to be configurable whilst my boiler is in opentherm mode, it requires that I manage that through Tado. So I have the hot water icon in Tado now and can adjust the temperature.

But given it is a combi, is there any issue with the hot water schedule in Tado showing as enabled 24/7 - I mean it should only use energy if I use the tap? Its not like its heating it all the time even though the app has the schedule as running hot water at 50 degrees all day?


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  • GrayDav4276
    GrayDav4276 ✭✭✭
    edited February 2022
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    Hi @Floob ,

    Your system is ONLY HEATING your hot water when you turn on a tap 👍✔️

    What you're seeing in the schedule is the water temperature that you have selected. You can add more "Time Blocks" into the schedule, if you want the water at a different temperature for a specific period.

    For example my "hot water" is set to 38° for most of the day......a perfect temperature for dish washing in the sink, or washing your hands etc. I increase the water temperature to 46° for bath/shower time ( I do this via Alexa )

    I also set the water temperature to 36° from midnight to 7 a.m. (when we're all in bed).

    I admit to being a "control freak" and don't see the need to "overheat" the water to a higher temperature than is needed, so I'm into utilising the feature to it's ultimate possibility.........😎

  • Floob
    Floob ✭
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    Thanks for that. This is what I wanted to hear:

    "Your system is ONLY HEATING your hot water when you turn on a tap"

    I was thinking that under 50 degrees could cause bacteria like legionella, but then I guess thats more for standing water rather than combis. I'll play with it a little and see what temp suits best. Thanks for your help.

  • GrayDav4276
    GrayDav4276 ✭✭✭
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    @Floob
    You don't have any stored/standing water, as your hot water is heated on demand 😎
  • SergG
    SergG ✭
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    I'm current researching wiring for hot water for my Greenstar Si Compact ErP. And decides to add a question to this slightly older post.

    My boiler is already connected for heating to Tado and is working fine, but I want to control ECO mode shedule as well. Professional installation guide for Wireless Smart Thermostat [Incl. Programmer with Hot Water Control] Manual explains 3 modes - S-mode, Y-mode and Combi. I wonder which one I should use with my Combi. Boiler details - https://www.worcester-bosch.co.uk/products/boilers/directory/greenstar-si-compact


    Here is an update for everyone who has a similar question - pre-heat hot water in a combi boiler:

    Why might I want to programme hot water times with my combi boiler?

    Worcester's range of wall-hung Greenstar gas combi boilers all feature a 'domestic hot water preheat' function.

    When this pre-heat function is on, the length of time taken to receive hot water at a tap will be reduced as the boiler will have been kept hot in readiness for a demand.

    If this function is off, the boiler will only ignite to warm the water once the tap is opened. This means delivery to the tap will take a little longer but energy will have been saved in not keeping the boiler preheated.

    For more details please read this guide - https://www.worcester-bosch.co.uk/support/troubleshooting/faqs/all-faqs/why-might-i-want-to-programme-hot-water-times-with-my-combi-boiler

  • johnnyp78
    johnnyp78 ✭✭✭
    edited October 2022
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    You’ve got a combi so s plan and y plan are irrelevant, those are for hot water tank systems. How is the wireless receiver wired - relay or Opentherm/ebus? If it’s relay then you control the hot water on the boiler, so it’s up to you whether or not to turn preheat on. If it’s digital then the preheat function may get overridden by Tado to be either permanently on or unavailable, depending on the boiler.

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