Evohome - fine tuning controls

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  • killa47
    Automated Home Guru
    • Jan 2016
    • 123

    #46
    Short cycling and zone valve control

    Ref previous posts by Edinburgh2000, DBMandrake and others
    I have digested everyone's earlier suggestions and advice re my short cycling/gradient limitation and plan doing the following:

    1. Disconnect upstairs CH zone valve cable wiring from wiring centre (presently wired in parallel to downstairs CH zone valve) and re-connect to Grundfos pump.
    Only connecting brown (to trigger open valve) plus N + E.
    Leave isolated Orange and Grey (prevents re-trigger of boiler).

    Above should keep pump on and upstairs valve open whilst boiler is sending pump overrun live signal. Happy letting towel rails and landing all with manual TRVs run.
    This then prevents the gradient limitation from tripping with rising flow temperature.

    2. Boiler control is maintained by BDR91 signal to downstairs zone valve and switch to Orange.

    I think above is a variation of a DBMandrake suggestion.

    I have one question if someone could advise:
    - the power rating as specified for a Honeywell 4043 zone valve is 2.2 amps and the Grundfos pump is .44 amp. Does this total of 2.64 amps risk anything when the zone valve is wired to the pump??

    Many thanks
    Last edited by killa47; 5 March 2017, 01:35 PM.

    Comment

    • mylesm
      Automated Home Guru
      • Nov 2015
      • 153

      #47
      Originally posted by killa47 View Post
      I have digested everyone's earlier suggestions and advice re my short cycling/gradient limitation and plan doing the following:

      1. Disconnect upstairs CH zone valve cable wiring from wiring centre (presently wired in parallel to downstairs CH zone valve) and re-connect to Grundfos pump.
      Only connecting brown (to trigger open valve) plus N + E.
      Leave isolated Orange and Grey (prevents re-trigger of boiler).

      Above should keep pump on and upstairs valve open whilst boiler is sending pump overrun live signal. Happy letting towel rails and landing all with manual TRVs run.
      This then prevents the gradient limitation from tripping with rising flow temperature.

      2. Boiler control is maintained by BDR91 signal to downstairs zone valve and switch to Orange.

      I think above is a variation of a DBMandrake suggestion.

      I have one question if someone could advise:
      - the power rating as specified for a Honeywell 4043 zone valve is 2.2 amps and the Grundfos pump is .44 amp. Does this total of 2.64 amps risk anything when the zone valve is wired to the pump??

      Many thanks
      I would think that the Zone Valve 2.2 amps is referring to the Switch Capacity not the Valve Power the valve Power is only 6 Watts which is only approx 0.03 amps at 230V

      Comment

      • G4RHL
        Automated Home Legend
        • Jan 2015
        • 1580

        #48
        Originally posted by DBMandrake View Post
        Three months sounds more like a faulty HR92 to me.

        Have you tried tweaking the battery contact tension on those ones ? I've had two now where they were falsly reporting low batteries, in one case when the batteries were new!
        Yes I have "tensioned" the battery contacts. I suppose what I ought to do is swap it for another one to check whether it is location/use related or a faulty HR92. I have not swapped one before. Does the Control Panel respond to the name given or is there some deeper hidden form of contact twixt HR92 and the Panel? If just a name then I only need to rename and not rebind. Lazy I know!

        Comment

        • killa47
          Automated Home Guru
          • Jan 2016
          • 123

          #49
          Originally posted by mylesm View Post
          I would think that the Zone Valve 2.2 amps is referring to the Switch Capacity not the Valve Power the valve Power is only 6 Watts which is only approx 0.03 amps at 230V
          Thank you mylesm - just what I was hoping an informed user would know. I had visions of blowing either the boiler or pump out of the "water" - so to speak!

          Comment

          • DBMandrake
            Automated Home Legend
            • Sep 2014
            • 2361

            #50
            Originally posted by G4RHL View Post
            Yes I have "tensioned" the battery contacts. I suppose what I ought to do is swap it for another one to check whether it is location/use related or a faulty HR92. I have not swapped one before. Does the Control Panel respond to the name given or is there some deeper hidden form of contact twixt HR92 and the Panel? If just a name then I only need to rename and not rebind. Lazy I know!
            The zone name is only superficial, the bindings are based on device serial numbers.

            If you just physically swap two HR92's between rooms and rename the zones you would have to reprogram your schedule because now the schedules for the rooms are swapped. Also your Domoticz graph history would be confused.

            If you want to swap them and rebind them - which I think is the best way to do it you have to be careful to clear the bindings properly at both ends or you can get fault log entries - which recently happened to me.

            So clear the bindings on the two HR92's first (long press on bind) and then go into each zone configuration in the controller, choose heating type, and choose zone valve, say yes when it warns you this will clear the binding, but then cancel back out after the binding has been cleared. You should see that it now says there are no actuators bound to the zone.

            This is the only way I know to fully clear the binding of previous devices - if you just go in and bind the new devices without doing this everything will appear normal but the devices will still be partially bound to their old zone...

            Do this for both zones then rebind the HR92's in their new zones.

            Comment

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