mircolino Posted September 3 Share Posted September 3 (edited) I live in a condominium with a centralized heat-pump providing floor heating and cooling. In my electrical panel I have a cable that in summer has 24V and in winter is switched off (0V). I have Home Assistant separate automations for heating and cooling. Is there a way to detect the presence of the 24V so I don't have to manually switch HA automations every season? Edited September 3 by mircolino Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
Shelly Rolf B. Posted September 3 Shelly Share Posted September 3 There are several possibilities. Must there be a feedback signal, voltage is now “0V”, or is 24V DC sufficient? Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
Members thgoebel Posted September 3 Members Share Posted September 3 The are two main solutions: (a) A Shelly with pull down resistor With a Shelly plus 1 or plus i4DC or UNI plus, 12V DC supply is possible. Other Shellies need min. 24V DC. (b) A Shelly with intermediate relay: 1 Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
mircolino Posted September 3 Author Share Posted September 3 1 hour ago, Rolf B. said: There are several possibilities. Must there be a feedback signal, voltage is now “0V”, or is 24V DC sufficient? A simple binary switch would suffice: off (24VDC not present) is "heat" and on (24VDC present) is "cool" Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
Shelly Rolf B. Posted September 3 Shelly Share Posted September 3 I have another idea, which is a bit unusual. HA can detect whether a Shelly is online, offline or the output is switched? Use a Shelly Plus UNI on the 24V, but the 24V on/off should not change frequently. Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
Dreckfresse Posted September 3 Share Posted September 3 8 minutes ago, Rolf B. said: HA can detect whether a Shelly is online, offline Detection in HA takes approx. 1 min to offline Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
Shelly Rolf B. Posted September 3 Shelly Share Posted September 3 A shelly can also be set to "auto on", if it is offline, the output is off or "na" Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
mircolino Posted September 3 Author Share Posted September 3 (edited) @Rolf B. The idea of the online/offline shelly is interesting. The 24V on/off changes once a year so that should be OK. I'm only worried about the HA Shelly integration seeing that as an error condition of some sort? I'll experiment and report back. I also like @thgoebel intermediate relay idea. Currently in my electrical panel the 24V is used in a ABB ESB20-20N-01 contactor to operate two dehumidifiers which, since they use cold water from the centralized heat-pump, they can only be turned on in summer. Can I simply add a ABB EH04-20N auxiliary contact to control the shelly? Edited September 3 by mircolino Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
Members thgoebel Posted September 3 Members Share Posted September 3 Yes, indeed! This is a suitable relay. 1 Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
Dreckfresse Posted September 4 Share Posted September 4 8 hours ago, mircolino said: HA Shelly integration seeing that as an error condition No, If the Shelly is not supplied with power, the condition in Ha is unavailable (like on and off from the relay) So this is not a error condition 1 Quote Translate Revert translation? English (American) Finnish French German Italian Portuguese (European) Spanish Link to comment Share on other sites More sharing options...
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