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  1. #1
    Automated Home Legend chris_j_hunter's Avatar
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    Default Electric UFH

    we're about to install electric resistance UFH in a small area (washrooms) ... and haven't bought the sensor or controller to go with the wire ... the idea being that timed intervals should be sufficient - ie: Cortex decides when appropriate (presence, button-press, time of day, whatever) & switches it on for maybe ten or twenty minutes (enough to heat, whilst leaving some margin relative to the don't exceed time) ...

    any thoughts, anyone done this, by any chance ??

  2. #2
    Automated Home Legend Karam's Avatar
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    Typically the floor sensors are thermistor types so should easily connect into a QAI, then you'd need some relay module to switch power to the heating wire (check wattage to choose which relay but if in doubt a DRH, SRH or QRH). In principle you could then set up a heating control loop around the floor temperature using an HVAC object, or you could do it more crudely just using QAI thresholds to control temperature and various inputs gating the operation period.

  3. #3
    Automated Home Jr Member
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    I had thought about this for our ensuite UFH and thought the easiest approach would be to wire in a relay module after the existing controller.

    So you retain the existing controller to read the floor thermostat and maintain the set temperature but set its timer to be always on. The idratek relay then switches the heater output on or off based on Cortex control.

    Otherwise you have to interface not only the floor heating element but the thermostat yourself. The standard fitting UFH controller has logic in it specifically designed to manage UFH elements, preventing overheating and the like, so there is some reason to continue to use it.

    By retaining it you then have the fallback of reverting to the standard control by setting the idratek relay on and using the controller to set heating periods as normal.

    The worry I'd have with your approach, Chris, is that the pad might overheat if it was just switched on without any floor thermostat sensor to check on its local pad temperature. Karam's approach of having a floor sensor, but using Cortex to manage the heat pad would be safer, but then you have the calibration issue of getting the thermistor integrated into Cortex.
    Last edited by achapman; 14th October 2011 at 03:19 PM.

  4. #4
    Automated Home Legend chris_j_hunter's Avatar
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    yep ... take the points ...

    when we bought the kit, the controller & sensor came separately, and doubled the cost ...

    so instead, to do without both, my thought was to first measure how the floor temperature rose with time, then allow Cortex to switch it on for only (say) half as much ...

    the washroom is a combined shower-room with WC etc & a small laundry area, with WM & drying area, and will be used mainly when the adjoining area is occupied, and we could maybe contrive to have some short warning of that ...

    and any heat generated will soon find itself distributed around the house, courtesy of the MVHR system ...

  5. #5
    Automated Home Sr Member ludditeal's Avatar
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    As Achapman has suggested is exactly how we have wired the heating in our Kitchen and plan to for our Hall floor. They are slate so we have them come on an hour or so in the morning before we get up with the times varying depending on working day or weekend.
    As far as I am aware the controllers are all the same so you can shop around. As long as they are rated for the load of the element. When we bought the hall kit it actually came with remote control and I was going to investigate using IR to control it but that is a long way down the list on the refurb at the moment. Racing to get house ready for rendering before winter sets in!!

    Regards
    Allan

  6. #6
    Automated Home Legend chris_j_hunter's Avatar
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    thanks again ... hmm, we bought one of these :

    http://www.warmup.co.uk/uk/loose-wir...g-system.phtml

    going for the loose-wire type because of the floor-standing sanitary-ware & the long-narrow room shape ...

    and the choice of control units might therefore be these :

    http://www.warmup.co.uk/uk/warmup-un...rmostats.phtml

    and since Cortex would do the clever bit, I guess the basic electro-mechanical version would be the one ...

    OTOH, using just Cortex with a time-limit might be more reliable, long-term, and would mean no problem in finding a place to site the thermostat, in-line with room zoning requirements (tricky in our case, due to bath & shower etc locations) ...

    OTOH, using any one of them would eliminate the need to calibrate ...
    Last edited by chris_j_hunter; 15th October 2011 at 03:16 PM.

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