Domoticz

I'm sure there is a simple answer to this - how can I detect in Domoticz whether a pump controlled elsewhere is on or off? (or I guess any other AC powered device).

I have a solar heating system for which I am using Domoticz on RPi as secondary monitoring (with a long term plan to connect Resol Deltasol thermal controller direct to domoticz but it's not that easy) - using 1-wire temperature sensors.

What I would like to know is when the 240v circulation pumps are switched on by the solar controller - I would rather that this is an electrically isolated mechanism rather than taking any direct feed from their circuitry to the RPi. I have no interest in the level of current flowing or power being consumed - just whether the pumps are on or off when the sensor is polled.

Is there some kind of simple hall effect sensor board which can be relatively easily connected to RPi/Domoticz ? They are physically close to each other.https://9apps.ooo/

Hi,
normally you can detect if 240V is applied or not by using a optocoupler.
Optocoupler is a device that has, in this case, a 240V input that is galvanic isolated by its output, so electrically it's very good for this.
The following picture is a bit complicated, but shows a similar case of your: the power supply to a heat pump is monitored by Creasol DomBus23 device throug its opto input, so in case of power outage or circuit breaker goes down, an alert is sent by Domoticz to Telegram and email notifying this potentially dangerous event (no power supply to heat pump and outdoor temperature below zero).
In your case, just connect the opto input to the pump, and you can know when voltage is applied to that pump.

if it is just switch on/off you want to know, you can connect a small relais in parallel to the motor so that the coil from the relais gets his power when the pomp is powered. and than you simply connect the contact from the relais with a pull-up resistor on to the GPIO from the raspberry and you can intregrate the GPIO with sysfs in domoticz.

You may also use a small neon bulb, in front of a LDR, with a pullup (or down) resistor. Isolation is very good, consumption is null, and cost very light...