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Thread: HVAC Object with no presence connection, what profile does it use?

  1. #1
    Automated Home Ninja marcuslee's Avatar
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    Default HVAC Object with no presence connection, what profile does it use?

    Hi All,

    Easy one (maybe), but for an HVAC object with no presence connection, what profile does it use?

    Unoccupied or Occupied?

    We're not using presence fully in the house, for a few reasons:
    1. we have babies present and we don't really want the lights to come on when we go in to check on them
    2. I notice presence detection rooms at night, mightn't necessarily show presence after occupants have gone to sleep. And in this case we don't want the room heating to drop off.

    Also with 2 babies under 2, this house is mostly a 24x7 operation (eg we still heat parts of the house, like kitchen dining over night, just for the fact we're getting all night long and dropping in out of the kitchen dining and odds and sod hours.

    Cheers,

    Marcus

  2. #2
    Automated Home Ninja Viv's Avatar
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    [QUOTE
    2. I notice presence detection rooms at night, mightn't necessarily show presence after occupants have gone to sleep. And in this case we don't want the room heating to drop off.
    [/QUOTE]

    If no connection is made to HVAc presence input then it uses the unoccupied profile.

    2. The HVAC Presence run-on period is designed to resolve this. That is say from 10pm to 7am assuming you typically go to be at say 10:30 pm you can have a run on period of say 8 hours. This gurantees it will follow the occupied profile throughout the night. At switch over at say 7am it then uses the day run-on period.

    Viv

  3. #3
    Automated Home Legend chris_j_hunter's Avatar
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    24/7 has been found by some to reduce heating costs - so could be interesting to hear what you find !

    we've been running ours 24/7, to get the (new-build) house dried-out & stable, and the bills have been quite encouraging - we've not run it otherwise, though, so can't compare like with like ...
    Last edited by chris_j_hunter; 21st April 2013 at 12:41 PM.

  4. #4
    Automated Home Ninja Viv's Avatar
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    Quote Originally Posted by chris_j_hunter View Post
    24/7 has been found by some to reduce heating costs - so could be interesting to hear what you find !

    we've been running ours 24/7, to get the (new-build) house dried-out & stable, and the bills have been quite encouraging - we've not run it otherwise, though, so can't compare like with like ...
    My own heating system is on 24/7 365 days a year. By 'on' I mean controlled. It can even come on occasionally during the middle of summer. Bedroom target temperature is raised just before we go to bed and allowed to fall during the night (a bit like system off) however the temperature is not allowed to drop below a specified amount. Other non-used bedrooms are allowed to fall down as low as 12C.

    Main occupied rooms like Kitchen, Lounge etc tend to be set lower in the day and raised during the evening when activity is more sedentary. So the system is set for comfort in occupied rooms and savings in un-occupied.

    If by 24/7 you mean maintaining occupied temperatures when not occupied then logically to me it cannot save money unless it is a heat source requirement. That is the heat source has such a large thermal mass (under floor heating) that you cannot get to occupied temperature in a timely manner. Or the operation of the heat source is more efficient in short bursts, or has a low temperature differential.


    Viv

  5. #5
    Automated Home Legend chris_j_hunter's Avatar
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    interesting ...

    yep, 24/7 but controlled is what we meant, too, ‘though in our case the control is largely manual, at the moment, while we get a feel for things ...

    new house does have high thermal mass, from concrete walls & floors, and does have UFH, and it's insulated to modern standards, is well draught-proofed, and has MVHR ...

    response time is long - turn the heating on & it takes two hours for the room sensors to start to register rising temperatures ...

    new house is all-electric, and the bills are running at about a third of what they were in old late‘80s gas+electric house (measured in kWhr/m2 of floor-area) ...

    new house is heated by ASHPs + vacuum-tubes + waste-heat from pumps & appliances & CFL + LED lights ...

    old house had gas for cooking & CH, and the usual twice a day controller ...

    new house is comfortable, old one seldom was ...

    the good insulation & draught-control helps, of course, and the solar collection, too, but our feeling is that the evenness of the temperature helps just as much - playing catch-up twice a day can be expensive ...

    plus the heat sources in the new house are sized for steady running, while the gas boiler in the old house was oversized for fast response, and oversizing is fundamentally quite inefficient ...
    Last edited by chris_j_hunter; 22nd April 2013 at 09:36 PM.

  6. #6
    Automated Home Ninja marcuslee's Avatar
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    Thanks for replies and and particularly the pointers. Will see how I get on, though with babies napping at any and all times, so far, it's looking like a 24x7 HVAC will be easiest (at least for those rooms).

    Cheers,

    Marcus

  7. #7
    Automated Home Ninja marcuslee's Avatar
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    I had a look at the auto generated HAVC User Defined menu, and I saw the "Change set-point" option.

    This is connected to HVAC object > Heating temporary Edit Set-point (using LCD).

    Why does it only use a temporary edit?

    Does that mean the main method to properly change the set point is via Profiles tab in Cortex / or web access?

    Also from the user guide "In other words it allows a temporary increase in room temperature when someone feels cold. It gets cleared automatically when the currently used profile )occupied or unoccupied) changes its level." Does that mean this temporary increase gets cleared whenever the room moves from Occupied to Unoccupied (and vice versa)?

    Thanks in advance,

    Marcus
    Last edited by marcuslee; 8th May 2013 at 02:21 PM.

  8. #8
    Automated Home Ninja Viv's Avatar
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    [QUOTE

    Why does it only use a temporary edit?

    [/QUOTE]

    The Connection 'Heating temporary Edit Set-point (using LCD)’ allows the user to change the set-point. It is, as its name implies, a temporary addition or subtraction from the current profile.

    The rational is that the profiles for various hours and days and occupied and unoccupied profiles are correct but the user wants to make a temporary change.
    It is partially to stop thermostat fiddling. That is, I feel cold, lets whack up the thermostat even though the room is already heating and not yet up to temperature.

    If for example you ask for say 2 degrees more on the current profile then this offset is added. If the profile in an hour’s time increases naturally by say 1.5 degrees, the user offset is now reduced to 0.5 degree thus maintaining the user requested temperature. If the profile naturally increased by say 2.5C then the offset would be cleared. Similarly if the profile drops (any amount) the offset is removed. The rational being that a drop in designed profile is because the room is likely to be unoccupied or the user more active and does not require the same temperature.

    But you do not need to use this 'Heating temporary Edit Set-point (using LCD)’ connection unless you are making your own menus.
    Rather you can use a menu MADE by the HVAC.

    Note: (where xxx is the HVAC name) DO NOT USE the 'xxx HVAC menu - Start' connection from a button. Rather use the 'xxx HVAC - Configure and Activate Menu'.
    The former starts the HVAC Menu as is (last built). The Later causes the HVAC object to re-build the HVAC Menu dynamically and alters itself depending on the prevailing conditions. This menu is very extensive.

    This menu will allow you to change the set-point and do it Temporarily, This hour only, Morning, Midday, Evening or Night.
    Then, if not temporary, you can choose it to apply to the Occupied or Un-Occupied profiles.
    Then, for that profile to be Today, All days, Week days or Weekend.
    Then you get a summary of what you have done.

    From this menu you can not only change the HVAC for the room where the button or HVAC is located but any of the HVAC's in the house.

    So the simple answer is, no it need not be temporary.

    Viv.

  9. #9
    Automated Home Ninja marcuslee's Avatar
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    Quote Originally Posted by Viv View Post
    But you do not need to use this 'Heating temporary Edit Set-point (using LCD)’ connection unless you are making your own menus.
    Rather you can use a menu MADE by the HVAC.
    Thanks for explanation Viv.

    And to double check, I guess that means if we are going to use the static menu, temporary edit is the only available option?

  10. #10
    Automated Home Ninja marcuslee's Avatar
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    Also, if the profile is set for a continuous 22 degrees, 7 days a week, 24 hours a day, the set point change is actually "permanent" so to speak, since the profile never actually changes?

    Also finally, on the "Profiles" tab, what does the "Heat Set-Point" and "Cool Set-Point" check points refer to?
    Last edited by marcuslee; 10th May 2013 at 05:37 PM.

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