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Thread: Will wireless relay take heater load?

  1. #1
    Automated Home Jr Member
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    Default Will wireless relay take heater load?

    I'm looking to fit a progamable wireless thermostat on some panel heaters, but i want to ensure the wireless receiver is upto the job of taking the load of the heaters. The spec for the receiver is shown below.....

    Receiver power supply
    : 230V AC +10% - 15%, 50Hz
    Switch type
    : SPDT potential free
    Output rating
    : 24-230 V AC, 10 A resistive, 3 A inductive0.6 p.f.


    For a 2KW PAnel heater would this be upto the job?

  2. #2
    Automated Home Jr Member Ad's Avatar
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    P = IxV = 10x230 = 2300W = 2.3kW

    whether you have 230v coming into your house is another thing, that relay looks to do +10% so 253V and -15% which is 195.5V. A quick google says the average UK incoming voltage is 242V. You do sit close to the limits when you talk about the lower voltages but if you have 240V coming in then you have 2.4kW to play with.

    Double check your heater consumes exactly 2kW though, personally if I had a choice just to be safe I would get a 13 or 16A relay but thats just a personal preference.

  3. #3
    Automated Home Jr Member
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    Thanks Ad.

    I would get a bigger relay, but finding one is another matter!!!!

    It's a thermostat with 7 day timer wirelessly controlling a relay i'm after, all the ones on the market are designed to control a boiler so have a rating usually around 3 or 5 Amps. This 10A relay is the biggest i can find.

    Finding a independent device to control electric panel heaters is not easy. I may end up having to go with a manufactuers more expensive all in one solution.

  4. #4
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  5. #5
    Automated Home Jr Member Ad's Avatar
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    Quote Originally Posted by nappyshock View Post
    Thanks Ad.

    I would get a bigger relay, but finding one is another matter!!!!

    It's a thermostat with 7 day timer wirelessly controlling a relay i'm after, all the ones on the market are designed to control a boiler so have a rating usually around 3 or 5 Amps. This 10A relay is the biggest i can find.

    Finding a independent device to control electric panel heaters is not easy. I may end up having to go with a manufactuers more expensive all in one solution.
    Not sure what device your using but it could be possible to use the 10A relay to trigger a 16A relay (or ebay for the word 'contactor' instead and you can find some that look easier to wire). Strictly speaking you can use the relay to control the heater providing your heater draws eactly 2kW you would be about 400W below the limit of the relay.

  6. #6
    Automated Home Guru Geps's Avatar
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    Back of the envelope calculations show at the higher voltage you've got a meager 500mA capacity and that's on the assumption it's a purely resistive load (which is won't be) and the startup inrush current is limited (which is unlikely).

    So for all those reasons I'd want to switch it with something that has a minimum 13A capacity - this would be revised if it doesn't have a typical 3 pin plug.

    Remember as well it's technically illegal to connect the 10A relay to a plug socket since it's limited to 10A and not the 13A the plug socket could require.

  7. #7
    Automated Home Jr Member
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    It would be hard wired on a fused spur. I'll possibly go for a 1500W heater or one just under 2000W and use a 10A fuse.

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