I have a challenge I want to solve but I am struggling to understand if it is possible in HA.
Challenge:
I have a pool pump I want to automate so I can control when it is on and drawing power, something like:
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If Solar production exceeds house consumption by 2Kw AND the water heater is not on, THEN turn on
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OR if solar production is less than house consumption OR zero, and the time of day is between 2am to 4am, Then turn on
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Else turn off
the conditional on is via a Shelly 1Pro PM which has the amps to drive the pump.
Then I need a manual On which a standard light switch could manage installed near the pump with its feed into the Shelly Relay (similar to turning on a light manually). This function is needed so that if the pool guy arrives he can override the HA automation off and use the pool vacuum skimmer.
So ok all easy thus far. but here is where I am struggling.
I need a third switch choice that is a manual action, being OFF. this is because when the pool guy cleans the filter of the pump itself, he needs to remove its top cover, to retrieve a small filter basket that lives inside the pump. valves to the pool are in a off position so the pool will not drain into the pump house. But If the pump was to start at this point all the water within it would be ejected and the pump would quick burnout.
So What I thought I’d do was use a two channel Shelly relay, with both outs going to the pump live. and use a single 3 position switch to power either channel A or Channel B of the Shelly relay. before doing this I asked Shelly what would happen, as I know they use their Shelly 2.5 with roller shutters for a similar 3 position challenge. However they said roller shutter have 2 live inputs so the 2 channels of a roller shutter are actually separated. They also said if I attached both Shelly relay channels to a single input and switched one on, Bad things would happen.
So the hack is to use a single Shelly relay and have it manage the two ON function (conditional via HA, and manual via one switch), and wire between the shelly and the pump a breaker simply used as a safe OFF.
While this solution will work, its ugly and is error pron. As it relays on the pool guy to remember to do two actions in two different places.
I would rather have both manual ON and OFF contained in a single switch I can set ON, OFF, Auto with. thereby simplifying the switching for the pool guy.
Has anyone done a similar exercise and or can throw me some advise on wiring a 3 position switch that HA can monitor and react to.
Thanks in advance
Duncan