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Smart switch for old storage heaters?

Discussion in 'Home Automation' started by Norfolk Broad, 9 Nov 2021.

  1. Norfolk Broad

    Norfolk Broad

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    Hello everyone

    I've posted elsewhere about a one bedroom flat I've recently bought with night storage heaters.

    As I don't stay there all the time, I'm looking for a means to remotely monitor the temperature over winter and, if possible, switch the heaters on and off.

    I don't want to get into the whole Nest thermostat thing: Too expensive, don't have a regular routine for it to learn, and I don't need to control the hot water.

    To keep costs down I'm considering a pair of these Govee thermometers to monitor the temperature in the lounge and bedroom:
    https://uk.govee.com/products/wi-fi...uYUzBeTSEzGRRpkg15xjiEgz_qrkHYkxoC-HIQAvD_BwE

    But to be able to switch the heaters on and off I've been trying to find Wi-Fi enabled fused spurs, but they're a bit thin on the ground, and seem awfully expensive for what they are:
    https://www.ledbulbs.co.uk/products...ot74AEl7ThT3_qBftfufeB3te3wvl5thoCV5IQAvD_BwE

    These ones are a bit more stylish, but don't have the means to fit a fuse:
    https://wifi-smart-home.co.uk/smart-wifi-spur-switch-32-amp-pure-glass/

    Am I missing a trick? Is there a simpler (and cheaper) way to do this?
    Perhaps fit a Zigbee hub and use a different type of switch (and temperature sensors)?

    Looking forward to your ideas and suggestions.

    Many thanks
    NB
     
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  3. Harry Bloomfield

    Harry Bloomfield

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    These suggest they are rated for 16amps - I bought and use 8 of them, but only for much lighter loads. Whether they will survive long switching a full rated load, is anyone's guess. Me, I would be powering a contactor from one, them feeding the heaters from the contactor.

    No special hub is needed, just an hub, internet access and something running Alexa. The Alexa may not be essential, there is an app provided by plug maker that may meet your needs.
     
  4. ericmark

    ericmark

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    Even using contactors with heating elements they did not last very long, this was in an industrial machine, we tried some solid state which worked better, but needed semi-conductor fuses, and without the fuse some times they failed on, but these were switching at around 2 minute intervals not just once or twice a day, so the Timeguard unit should take the load OK, and in a steel back box in a plaster or brick wall can't see any problem.

    This is one time where I would say a smart meter makes sense, normally hate the things, but being able to check if they have switched off is good.
     
  5. Harry Bloomfield

    Harry Bloomfield

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    I don't understand that comment, because I have known contactors last for many decades - and especially so on a resistive load. I agree solid state switches would be more reliable, but last time I looked they were much more expensive than a simple contactor. A single contactor with a 240v coil, three sets of contacts, rated 15amps will quite cheap and able to switch three storage heaters, with the coil powered from a Smart Plug.

    Smart Meters have no facility to be monitored remotely, beyond the building, by anyone except the energy company. An appliance could have been stuck on for days, before its consumption is spotted on the bill, even if you could be bothered to check regularly. Smart Plugs can be monitored, remotely controlled manually and you can tell whether or not they have operated. It still doesn't prove whether the contactor has operated correctly, but that risk is quite tiny.
     
  6. SpecialK

    SpecialK

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    I would go with shelly 1's driving contactors.
    You can also get an add-on that will support 3 DS18b20 per shelly and they are very accurate when recording temperatures.
     
  7. Norfolk Broad

    Norfolk Broad

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    Thank you everyone for your comments.

    I hadn't appreciated there were Wi-Fi enabled contactors available, amazon and other stores tend to guide you to smart plugs etc. Is this the kind of thing you were talking about, Harry?
    https://www.amazon.co.uk/Circuit-Br...locphy=1006964&hvtargid=pla-736985684059&th=1

    They're certainly cheaper, and probably more robust, than the Wi-Fi fused spurs I've been looking at.

    Thinking about the switches currently controlling the storage heaters, these are only 20A-rated switches with no fuse. It's only the auxiliary convector which has a fused spur, which I don't intend to tinker with. The MCBs feeding the heaters are only rated to 16A, so the Shelly 1 units that SpecialK referred to look pretty useful.

    I suppose the other thing to consider is that the power to these contactors is only during off-peak hours but, once "activated", they will listen out for a signal from the app (or hub) on whether they switch on, and for how long. I'm guessing this is how it would work?


    Thanks again for your help.
    NB
     
  8. SpecialK

    SpecialK

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    I wouldn't use the shelly 1 on its own to switch a heater. It might work for a few weeks but would eventually burn out. They are not rated for a high load for a long time.

    The shelly can be used to drive a contactor..

    If they are on economy 7 you would need to bypass it and have the heaters powered up permanently, the smart switch would then control the heater. Unfortunately most smart switches are fairly limited in their own software. The shelly 1 can turn on and off to a schedule or be controlled by the temp sensor (I'm not sure it can do both). If you wanted it smarter then you would need to control it via home assistant or something similar.

     
  9. Harry Bloomfield

    Harry Bloomfield

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    I didn't realise there were wifi enabled contactors, but yes, that would be an even simpler solution.

    You program them with a time (or other event) to turn on, and either a set time, or amount of time to be on for, or other event to switch off.

    For instance I have one Smart Plug controlling a single light on my drive. I have it programmed to come on 17 minutes after dusk, then go off at 11pm every day. The Smart Plug replaced a solar time clock, which was quite old and would need to be reset every time we suffered a power outage.

    Aside from that single light, I have some much bigger lights around the outside. Those are powered by another Smart Plug, but used manually as needed. I can simply speak to Alexa and say - 'Alexa, turn main drive lights on'. Away from home, I can do the same using my phone. I have 8 of these plugs, some set up to turn lights on and off inside, to give an appearance of there being someone in when we are away as a deterent. Some turn Christmas lights on and off, at Christmas.
     
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  11. Norfolk Broad

    Norfolk Broad

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    Ah, I'm starting to understand now. Thanks!



    This is starting to get too clever for me at the moment. I'm happy just to monitor the temperature (and humidity) myself, and intervene remotely when I need to, but thanks for the ideas.



    Do you think these would still work OK if fitted to the E7 consumer unit (only "powered up" for seven hours overnight)?
    Perhaps another drawback is the CU is made of steel, and located in a cupboard, which may restrict the Wi-Fi signal. Might be worth a try, though.

    But what do you all think of this gizmo? Ability to control four things for under £100 (which is about my overall budget for this!):
    https://shellystore.co.uk/product/shelly-pro-4pm/

    I'm guessing it lacks the robustness of a mechanical contactor?


    Thanks again to all of you.
    NB
     
  12. Harry Bloomfield

    Harry Bloomfield

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    That has a great deal of promise, if the rating of 16amps is up to the job. Regarding the E7 issue...

    You would permanently power your unit and simply set it to only come on during E7 off-peak times. Any juice you consume during off-peak is charged at the cheaper rate, irrespective of what method you use to actually switch it.
     
  13. SpecialK

    SpecialK

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  14. Norfolk Broad

    Norfolk Broad

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    Thanks again, guys

    I have a lot more confidence in DIN rail mounted devices! The SONOFF is looking quite chunky, though. I'm not averse to fitting a small surface mounted enclosure next to the heaters, if that's what it takes.

    And, once again, a disappointing price difference between the USA and UK!
    https://www.amazon.co.uk/SONOFF-POWR3-Power-Smart-Switch/dp/B09B9QRXWK

    I'll do some more shopping around.


    By "unit" I presume you mean the night-time consumer unit? I guess that's easier (and safer?) than transferring the MCBs/contactors to the standard consumer unit?


    Expressing my ignorance here: is permanently powering the night CU a job for an electrician, or do I need to get my energy supplier to do it?
     
  15. Harry Bloomfield

    Harry Bloomfield

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    It depends on how it is wired what is presently used to turn them on and I have little knowledge myself of E7 - so best to post photos of what you have and ask again in the forum.
     
  16. foxhole

    foxhole

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    May have missed the point but don’t night storage only run overnight and have little or no manual control during the day heating period ?
     
  17. Harry Bloomfield

    Harry Bloomfield

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    The basic E7 manual control, is to simply to turn them to off, either on the heater itself, or at the isolator next to it. What the OP wants, is to be able to remotely decide whether they need to be on, or not.
     
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