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Thread: honeywell evohome - is it doable setup

  1. #21
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    Right, so not the same. As it has been explained to me heizungsstrom allows people in Germany to create hot water buffers at a strongly reduced price per kWh during the night. Thus the hot water is already there for comfort when the heat is turned on in the morning. Your setup seems very tricky to me as you are essentially deprived of any heating during a number of 40 minute periods spread throughout the day and the only hot water you do have stored for comfort is in the radiators themselves.

    I suppose if your pattern for turning on/up the heat stays clear of those 40 minute "blackouts" that will work just fine with Evohome. If I were in your place I'd probably use a timer as a secondary trigger for the boiler, say 5 minutes before a planned blackout period starts in which I may be likely to generate a heat demand. You might need a bigger and/or better insulated boiler for that though.

    PS I think the Evohome phone app has the same .5 degree resolution as the central console. You should have a look a the various home automation projects, e.g. Domoticz supports Evohome with a temperature resolution of up to two decimals. If you are into programming you can also create an app yourself. Libraries for accessing the API are available in various scripting and programming languages, like python, js, cpp and c#.

  2. #22
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    Quote Originally Posted by DanD View Post
    Thanks for the additional info on how the 40min periods are spread throughout the day. I'd wrongly guessed that more of them would be grouped together near times if highest demand e.g evening. I think the Evohome system will cope OK with them. If the BDR91 requests heat during one of the off periods, it will continue to request heat until the end of the off period and the boiler starts. It will only stop asking for heat when the zones are comfortably close to their setpoints.
    but what about its fuzzy logic...?

  3. #23
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    I don't think these 40min no heat periods will mess up the Evohome controller's 'fuzzy logic' heating optimisation algorithm. My confidence is due to the fact that even with standard gas boilers there are periods where they don't respond to a heat demand from the BDR91. These situations can be due to a design setting on the boiler where it only allows requests for heating at a certain frequency so that it isn't constantly turning on and off which is inefficient or it may have been set-up with hot water priority so it preferentially heats the hot water for washing rather than for the central heating. Based upon the experience of other Evohome users who have these types of installations it should work OK.

    As Gordon has explained, it is also possible to either control Evohome by additional software which could alter the temperature setpoints in your zones as often as you like or add an additional timer control to your boiler prior to each of the 40min periods.

    Dan

  4. #24
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    I am more afraid about the accuracy of the evohome...

    right now control unit shows 22C, target temp was set to 22C ... but my other two thermometers show 23.5C and radiator is still hot... so i am not sure if it is able to control tempreture as set/expected in the room. no clue why this is happening?


    thanks

  5. #25
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    The only comments I can add are that my experiences with the use of the Evohome controller as a room temperature sensor have been positive. You also have the option to use the temperature sensors within the HR92s themselves which also works well for me and is more convenient than the use of the controller as they are obviously located within each zone. The results that you are observing may possibly be that the Evohome controller is less sensitive to rapid changes in temperature as it is intended to smoothly control the temperature in a room and it might be smoothing out rapid changes in temperature, but this is only a guess. If the controller is continually reporting a lower or higher temperature than you feel is accurate then you can also use the 'internal offset' feature which allows you to correct for this.

  6. #26
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    Quote Originally Posted by phier View Post
    I am more afraid about the accuracy of the evohome...

    right now control unit shows 22C, target temp was set to 22C ... but my other two thermometers show 23.5C and radiator is still hot... so i am not sure if it is able to control tempreture as set/expected in the room. no clue why this is happening?


    thanks
    Are you sure that you are measuring what you think you are measuring? While it is possible to configure the controller to be the temperature sensor for the zone where it is (always) in, the default is that the first HR92 you define as part of a new zone will become so and every subsequent HR92 you add to that zone will reference that first unit to determine whether it should open or close its valve. You could be seeing the temperature in another part of the room or since you are apparently still in the experimental phase even a different room all together or the cabinet where you keep the units you did not mount yet.

  7. #27
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    Quote Originally Posted by DanD View Post
    The only comments I can add are that my experiences with the use of the Evohome controller as a room temperature sensor have been positive. You also have the option to use the temperature sensors within the HR92s themselves which also works well for me and is more convenient than the use of the controller as they are obviously located within each zone. The results that you are observing may possibly be that the Evohome controller is less sensitive to rapid changes in temperature as it is intended to smoothly control the temperature in a room and it might be smoothing out rapid changes in temperature, but this is only a guess. If the controller is continually reporting a lower or higher temperature than you feel is accurate then you can also use the 'internal offset' feature which allows you to correct for this.
    I dont want to use temp sensors within the HR92s because temp around these valves is different as reference temp in the room where controler is placed. Well less sensitive within one hour? both thermomethers shows 23-23.5C for about 2 hours ... evo controller still 22, target temp 22 and now the boiler is running ... so thats strange... no rapid chances of tempreature in room... no window opening etc.. no freezing outside. Yes I saw that offset but its not possible to set it correcly because lower tems 20-21 are showed properly on contoller but everything over 22> is not showed correctly. I was thinking to but wall thermometers which is honeywell selling and measure temp / control temp via these meters... linked with controller unit.

  8. #28
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    Quote Originally Posted by gordonb3 View Post
    Are you sure that you are measuring what you think you are measuring? While it is possible to configure the controller to be the temperature sensor for the zone where it is (always) in, the default is that the first HR92 you define as part of a new zone will become so and every subsequent HR92 you add to that zone will reference that first unit to determine whether it should open or close its valve. You could be seeing the temperature in another part of the room or since you are apparently still in the experimental phase even a different room all together or the cabinet where you keep the units you did not mount yet.
    Hello,
    yeah i explicitly changed that inside settings that controller has to act as a tempreature sensor instead of HR92s. Righ now my config is one controller, 2 valves in one room, ie one zone. And its showing weird tempreatures. no clue. But 1.5C difference on controller compare to 2 external thermometers located 5cm away from controller is crazy...

  9. #29
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    Ok to be more precise ...I have Electric boiler but some low end ... http://www.augur-kovo.cz/Electrother...ctric-boiler-b ... more sophisticated device might be for example this one
    https://www.thermona.az/getattachmen...10-06.pdf.aspx

    I was told that also Flowrate / pressure are important .. and if not set-up properly no Zone regulation will work correctly...

    So many confusion here...

  10. #30
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    Quote Originally Posted by phier View Post
    Ok to be more precise ...I have Electric boiler but some low end ... http://www.augur-kovo.cz/Electrother...ctric-boiler-b ... more sophisticated device might be for example this one
    https://www.thermona.az/getattachmen...10-06.pdf.aspx

    I was told that also Flowrate / pressure are important .. and if not set-up properly no Zone regulation will work correctly...

    So many confusion here...
    And the boiler makes up the whole system? You do not have the storage tank as shown in the diagram on page 48 of the second document?

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