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Thread: Heating logic

  1. #1
    Automated Home Guru JonS's Avatar
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    Default Heating logic

    I am rolling out zone per room heating controls upstairs, having done this downstairs previously. The upstairs has been a single zone with average temp inputs from all rooms. I need to roll this out in stages, so I've added an HVAC + zone valve to the first rooms and it all works as expected. However to ensure that the remaining rooms still have heating I want the old all-upstairs HVAC and the new per-room zones to be able to call for heat. To do this I converted the upstairs zone valve to a slave valve with the upstairs HVAC and the per-room zone valves as inputs. Cortex didn't like this as with an HVAC object on the input of the slave valve the "add" button didn't work. I removed the HVAC then added the HVAC and zone valves in one - all looked good. Added to this I had configured all the rooms with a heat load and enabled a boiler object to achieve minimum load.
    On testing I forced one of the per-room zones on which forced the zone valve and slave on - good. I then removed the call from the HVAC object - the zone valve switched off, but the slave valve stayed on. Even after a restart and switching the HVAC object and the zone valve off, and the boiler object off (not physically connected to the boiler) the slave valve still said the test-room zone was calling for heat, and remained open.
    I saved the database and reverted to a back-up (another story).
    Any ideas how to get the mixed per-room and multi-room HVACs to work together with a single physical heating zone?
    Thanks
    Jon

  2. #2
    Automated Home Legend chris_j_hunter's Avatar
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    Default

    not sure follow the detail, but do wonder if run-on times are playing a part here - ie: should you wait a bit longer before concluding ... ?
    Last edited by chris_j_hunter; 20th October 2015 at 11:41 AM.

  3. #3
    Automated Home Guru JonS's Avatar
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    Default

    Hi Chris
    The layout:
    per room HVAC > per-room zone valve \/
    rest-of upstairs HVAC > .......................... > slave valve (physical heating zone valve for top floor)

    I was using the defaults for run-on times - for the HVAC these can be cleared (I did) and the zone and slave valve times are seconds. I think I waited over 30 mins by which time it was getting quite warm, next time I'll try on a colder day / leave the heating off all day first :-)
    Hoping Karam or Viv will be along to explain how I should have done it
    Thanks
    Jon
    JonS

  4. #4
    Automated Home Legend Karam's Avatar
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    Just a quick one .. so is what you want that whenever a room calls for heat it needs to operate its own valve AND the valve which supplies hot water to the whole floor? If so then why not connect the floor valve to each room's HVAC as well as the room's own valve?

  5. #5
    Automated Home Guru JonS's Avatar
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    Default

    Hi Karam, thought about that but understand the slave valve is supposed to follow demand from multiple zone valves, so a neater solution. That is how downstairs is configured. Will try the multi zone valve in HVAC object next.
    Thanks
    Jon

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