Shelly 2.5 channel 2 overheating

  • Hello everyone :)

    I searched the forums and didn't find an answer for my problem. I am using a Shelly 2.5 to control 2 heating resistors. On channel 1 I have a 800W resistor and on channel 2 I have a 1200W resistor.

    When I turn on channel 1 in the shelly app, the relay immediately turns on, the button turns blue and power info is immediately shown. After a short time, the inner temperature sensor reading stabilizes at around 77ºC :)

    When I turn on channel 2 in the shelly app, the relay immediately turns on, but power info and the blue button only appear after 5 or 6 seconds. The inner temperature sensor reading starts rising and, after less than 5 mins, it overheats at 95ºC. It's unusable. :(

    1200W at 220V ~= 5A, which is about half of what it should be able to handle.

    I have tried rebooting it, factory resetting, but nothing changed. I am starting to think it might be faulty.

    Any help / comments are appreciated. Thank you in advance.

    I have attached the wiring diagram.

    • Best Answer
    • Official Post

    Unfortunately, the Shelly 2.5 is the wrong device for your project. Use 2x Shelly1 or 2x Shelly 1PM or, if possible, connect 2 external relays via which the loads run.

    The Shelly 2.5 has a known overheating problem, loads over 300W can lead to overtemperature shutdown

  • Thank you for your answer. I did just that, bought 2x Shelly 1PM and it works fine: ~65ºC at 5A.

    It annoys me that Shelly 2.5 can only handle a few Amps, when it advertises 10A...

  • Hi All,

    I am new to the community, but not new to the shelly world. I love your little products. They are just amazing!

    Just wanted to ask why does the shelly 2.5 overheats with 5A load? Any idea if this is something that can be fixed with firmware correction?

    I was considering to use Shelly 2.5 to control my ceiling lights, but must confess that I am feeling a bit hesitant.

    I have 10 shelly 2.5 controlling my roller shutters, and most of them sit at around 52 to 54ºC when idle. This is way too much when compared with Shelly 1PM, that sits at around 31 to 32ºC when idling (I currently have 5 of them for Ceiling lights with single switch on each of them).

    Can Shelly team please explain with more technical detail why the 2.5 is significantly hotter?


  • I am new to Shelly but i concur with Olsche based with my very limited experience:

    - Shelly 2.5 is mounted on a DIN rail between a module and the plastic case in a basement at 13C. So poorly ventilated but not a hot place.

    - Channel 1: 11W

    - Channel 2: 35W

    - Reported (internal) temperature stabilizes at around 67.5C.

    I did not even dare to try a Shelly 2.5 on a more hungry circuit (400W+500W): i will use a Shelly 1 instead. I am not so much worried about a fire hazard but more about the life expectency of the device.

    I do not mean to be negative because i really love the devices for many reasons but i think that the documentation should be more explicit about the recommended sustained usage range vs the 'technical' upper limit because the 300W mentioned by Olsche is a long way from the 2200W+ (10A). Personaly when i first read the specs, i assumed that 50% (aka 1100W) would give plenty of margin but that does not seem to be the case.

  • Hi Guys

    I’m new to the forum, iv connected the Shelly dimmer 2 on 2 way switching and have experienced many issues like overheating and offline issue can anyone help?