Howto shutoff heat pump when LWT<30 using Onecta integration

[MikeScottCAD (Mike)]

I’m too invested now, I need this to work for you haha. I still think the trend might be helpful here (unless I’m mistaken), or actually a Derivative sensor might be better still, but the concept of trend tracking applies. Lets focus on the logical execution before tackling what exact sensors need to be made.

Okay so, re-reading your posts a couple times, and using some newly defined (hypothetical) variables, are the below logical statements correct?

The offset is tied to your desired room temp. A warmer room temperature will make the offset -ve, and colder room temp will make the offset +ve. Reaching the desired room temp, the offset is 0

let’s assume/create the following HA variables
adjusted_lwt = actual_lwt + offset
actual_lwt_trend is the derivative/trend sensor.

@DCITH

The downward trend of a reducing actual lwt + negative offset can be handled because the result, if < 30 means, means turn off the pump but we need to ensure that lwt is reducing not increasing (or static).

1. IF actual_lwt_trend is decreasing AND adjusted_lwt < 30; turn off pump (I know, this part was the easy-to-handle part)

@DCITH

The downward trend of a reducing actual lwt + positive offset cannot be handled easily because for example if the actual lwt is 20C and positive offset is +2 then result is 22 in which case we turn off the pump (i.e. <30) BUT we actually want the pump ON so that the actual lwt rises as water is heated. Then when the offset changes to zero because the desired room temp is met, if the actual lwt is still below 30 then we want the pump off.

2. IF actual_lwt_trend is decreasing AND offset > 0 (i.e. positive); turn on pump (here we ignore the adjusted_lwt formula as you said there are scenarios where it won’t resolve to >= 30, and instead simply use the presence of a decreasing trend and a +ve offset to turn the pump on)
3. IF offset == 0 AND adjusted_lwt < 30, turn off pump
4. IF adjusted_lwt >= 30; turn on pump (this blanket addresses any scenario where actual_lwt + offset is >= 30 where you want the pump on)

---

Sorry I don’t seem to understand water heating systems as well as you. As such, the above logical statements are seemingly a gross simplification (maybe even incorrect) of what you may want to achieve. But, my end point is you don’t have to only use the trend/derivative sensor…it just becomes an additional sensor in your arsenal to solve your logic problems (as seen in logic #2)