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Thread: Tracking down random boiler demand with Evohome

  1. #131
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    Quote Originally Posted by jonstatt View Post
    That's not what anyone is saying. Evohome doesn't know the outside temperature and it doesn't need to. The FAQ referred to "weather". It doesn't really know the weather, but the weather will affect how the temperatures drops in every room over night so there is still a direct relationship between "the weather" and how EVOHOME reacts. All EVOHOME knows is the temperature in any room at any given time, and learns how long it takes to get from that temperature to the target one. That's it. All we are saying is that the weather affects what temperature deltas EVOHOME will have to deal with throughout the course of the year. It's a causal relationship.
    agreed - (I think we're saying the same thing in different ways) - but it's (IMO) it's essentially irrelevant to the way that optimisation works

  2. #132
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    Quote Originally Posted by Mavis View Post
    Right, last night I went to bed with the controller and kept watch.

    The general lowest temp during the night around the whole house (apart from our bedroom) was 16c. All radiators apart from our bedroom have optimisation activated.

    Hall - Set point 19c at 6am. Rad came on at 5.10 with an actual temp of 17c. Temp at 6am - 19.5c. Radiator felt cold at 6am (ie it had been off a while)
    Bathroom - - Set point - 19c at 5.50. Rad came on at around 5.20 with an actual temp of 16.5c.
    Sitting Room - Set point - 18c at 6am. Rad came on at 6am with an actual temp of 17c
    Bedroom 2 - Set point - 18c at 6am. Rad came on at 6am with actual temp of 17c
    Kitchen - Set point - 19c at 6.20am. Rad came on at about 6.05am with actual temp of 17c
    Bedroom 1 - Set point 17c at 6.40am Rad came on at 6.40am with actual temp of 12c (no optimisation set) (Window was open during the night but think there is an issue with this rad setup as I took the DTS92 out of this room. Room temp at 17c is red hot so will maybe delete and rebind)


    So my very basic conclusion is that optimisation only kicks in if the temp is >1c from the setpoint. But still not sure why it kicks in so early.
    in my view they all look about right - ignoring bedroom 1 the only one with a potential issue is the Hall that came on 50 minutes early to heat up by 2 degrees which it did quickly (as radiator had cooled by 6am)

  3. #133
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    Quote Originally Posted by top brake View Post
    Well put


    A radiator heating system is sized to raise 3 degrees per hour so on a normal day it will take anything between 1 and 2 hours to raise temperatures to comfort level
    If my heating took that long to warm I would be complaining.

  4. #134
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    [QUOTE=Mavis;21300]Right, last night I went to bed with the controller and kept watch.

    Thats not a nice name to give your husband!

  5. #135
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    Quote Originally Posted by G4RHL View Post
    If my heating took that long to warm I would be complaining.
    That's easily how slow my kitchen is to warm up and its a relatively modern house (built 2006) with polystyrene in the cavity of the walls. The trouble is that the windows have to be wooden framed due to being a protected area. And I don't like to keep the door closed on the kitchen so some of that heat escapes into the hallway

  6. #136
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    Quote Originally Posted by orange View Post
    agreed - (I think we're saying the same thing in different ways) - but it's (IMO) it's essentially irrelevant to the way that optimisation works
    Whilst jonstatt has said Evohome does not need to know the outside temperature the guidance when you go to settings indicates it does take account of it. Without an outside sensor it is not possible bearing in mind it works without the Gateway so cannot always access a weather forecast. It will know current temperature inside and what is called for and then presumably calculates how long is needed to bring it up the set point. In my case, taking my lounge as an example where it set at weekends to come on at 06:40 at 20C because I know almost without fail optimisation will click in around 05:40 which is when I want the heat, it is at a comfortable temperature within 10 minutes or so and at the set temperature usually well before 20 minutes all from a start temperature of around 15 to 16C but then last weekend when the start temperature was around 14C within 10 minutes the room was comfortable. It certainly gets it up to set point well before the heating is needed which is why I have it set so that I am using the optimisation period as one where I need the heat on.

  7. #137
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    Here's what the carbon trust say about optimisation


    https://www.carbontrust.com/media/13...rt_control.pdf
    I work for Resideo, posts are personal and my own views.

  8. #138

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    Its a 'red herring' for the UK (unless you just fancy looking at the weather onscreen and happen to have one of the hometronic sensors) - but for other regions outside weather function is useful for other countries like the German market where boiler control is directly performed this way - with no radiator demand and different system altogether. Thanks for posting up my previous post on this.
    getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own

  9. #139
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    [QUOTE=G4RHL;21316]
    Quote Originally Posted by Mavis View Post
    Right, last night I went to bed with the controller and kept watch.

    Thats not a nice name to give your husband!
    At least it doesn't hog the duvet and does what I tell it (most of the time)

  10. #140
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    Quote Originally Posted by top brake View Post
    Here's what the carbon trust say about optimisation


    https://www.carbontrust.com/media/13...rt_control.pdf
    Useful article. I note it talks of an external sensor. Do Honeywell do an external sensor that links wirelessly to Evohome?

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