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Thread: Heating Partial Load

  1. #41
    Automated Home Ninja
    Join Date
    Mar 2017
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    Quote Originally Posted by bruce_miranda View Post
    Just make sure you don't have a Zone Valve on the CH that shuts off before even the first radiator. That's when the bypass is really needed.
    It's a combi, so there should be no motorised valves as the system isn't zoned as far as i'm aware.

  2. #42
    Automated Home Lurker
    Join Date
    Oct 2011
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    9

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    I have a Vaillant ecotech 843 IQ with a EVohome system. The problem with the Partial Load D.000 set to auto is that when one or two rads call for heat it will often throttle the CH output so low that the CH water temp is only showing 40C for 30 mins or so - so no rapid heating of a room as required. I have set Partial Load to 24kW which stops this happening. D018 pump mode can also be set to Comfort which keeps the pump running all the time there is a heating demand. Finally I have reduced the anti-cycling time to allow the Evohome setting to dominate.
    It does seem that all these eco controls are not suitable when the boiler is controlled by a simple on/off demand switch especially in old houses when individual rooms will have very different heating requirements

  3. #43
    Automated Home Legend
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    Jul 2014
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    1,054

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    This is where OT should, in theory, really help. The ability to vary the Target flow temperature based on Heat Demand is what is needed.

  4. #44
    Automated Home Jr Member
    Join Date
    Nov 2019
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    34

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    Quote Originally Posted by rarrarrar View Post
    I have a Vaillant ecotech 843 IQ with a EVohome system. The problem with the Partial Load D.000 set to auto is that when one or two rads call for heat it will often throttle the CH output so low that the CH water temp is only showing 40C for 30 mins or so - so no rapid heating of a room as required. I have set Partial Load to 24kW which stops this happening. D018 pump mode can also be set to Comfort which keeps the pump running all the time there is a heating demand. Finally I have reduced the anti-cycling time to allow the Evohome setting to dominate.
    It does seem that all these eco controls are not suitable when the boiler is controlled by a simple on/off demand switch especially in old houses when individual rooms will have very different heating requirements
    This is almost exactly what I have done. I've set heating partial load to a little more than the maximum of all my radiators open at once, D.018 to comfort, D.014 to 100% (thanks @mtmcgavock - this made a big difference, along with opening all the lock shields to full) and anti-cycle time to 15m, so at a 70 degree target flow the anti-cycle time is 2.5m.

    What's your anti-cycle time set to?

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