Monitoring a voltage change from 0v to 240V

I have converted my hot tub to gas using a camping boiler and three way central heating valve, when the hot tub calls for heat (I have disconnected the heater element) the three way valve changes over and diverts the flow via a central heating pump out to the boiler and returns via a one way valve back into the heating line. The hot tub uses a Gecko heating controller and this controls the heating, pumps and lights however I would like to monitor when the hot tub calls for heat and although the Gecko does have wifi connection and can show if the hot tub is heating it only shows real time. So has anybody any idea how I could monitor the heat output voltage so that when it triggers the 3 way valve ie changes state for 0v to 240v it would allow me to map this state change.

Could you use something like this.

Why not use a 240V coil relay on the lines that used to be the heating element and place an inputs device on the dry contact side of the relay, this could be a hacked Zigbee door contact sensor, a Shelly UNI, etc.

One of the zigbee type of power monitors?

I was going to use one of these to detect when my house heating boiler fires.

1 Like

If it just needs to monitor 0 going to 240, then connecting a Z Wave or Zigbee switch module to the permanent supply and connecting the S1 switch input of that module to the 240V live of the 3 way valve will give you what you need. Effectively every time the valve is powered by 240V the module will see the switch state change to on and when the valve switches back the star will be off. You can then use the on/off events of the module to reflect call for heat/idle.

That's similar to what @nclark is suggesting with a relay and contact device. However with a Z Wave/Zigbee switch you've just got one module and 3 wires to connect - Permanent Line, Neutral (supply for the module) and Switched Line to trigger it via S1 (nothing need be connected to the load of the module as it is solely to monitor the voltage via the switch input)

1 Like

Strangely enough I started to think along the same lines, so I can just check the events and see when the switch/relay is turned on. Now I need to see if I can extract these events. Many thanks for your help.

1 Like

Yes you can just choose to reference those Switch On & Off events as triggers as you please in any rules - whether that be to send you an alert or show the status on a dashboard or whatever else you might want to do.

If you look in Hubitat Package Manager for 'Notification Tile' by 'thebearmay' that might be of interest. It can store a number of events, so you could display the last x number of switch on times for instance.

Perhaps give us an idea of what you want to do with the information, for ideas of how to achieve what you want in Rule Machine.

So since converting the hot tub to gas I can no longer monitor the energy it is using as it is now on a LPG bottle. The cost savings are dramatic, before conversion at our new rates it was costing about ยฃ4 a day to run, now itโ€™s 84p. However I donโ€™t have any idea how much gas is being used other than when the bottle runs out, I know the flow rate to the boiler so I am thinking if I can monitor when the heating is switched on then it would be relatively simple to work out the gas usage and get an alert when the bottle is nearly empty. Alternatively I guess I could just get an auto switchover valve and when the bottle is empty it automatically switches to the full bottle, but it would be useful to get an alert. For those wondering what the advantages are going to gas, other than the dramatic cost saving the heating is so much more efficient, for example if I refill the tub and say the water temperature is 18c then to get to 38c by electric would take about 20 hours, with the gas it takes 2 hours. This is a hard shell hot tub BTW. Although I have insulated the connecting pipes my only concern is the pipes freezing but I am thinking I could have an external thermometer and if the temperature drops below a certain temperature fire up the heater for a minute to keep the pipes warm.

I have a propane monitor on my tank. I believe there's an integration with Hubitat, though I don't use it. Tank Utility is the name. It connects via wifi and phone and comuter website. . Generac now owns it.

You can easily capture the switch turning on and off through the module. With a rule you could write that on time to a variable and the off time to another variable. I wonder if it's possible to subtract one time from the other, calculate the difference and record accumulated time.

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.