What Wiki topics should I read to realize differential (solar) thermostate?

[Laurentp]

Hi there,
please point me at Tasmota Wiki topics I should read to realize solar thermostate.
- Sonoff Basic + 3 DS18B20 (solar panel, solar return, water tank - at top), output - solar liquid circulation pump.
Now rules:
- settable difference temperature (may be from Tasmota console) between solar panel and solar return to start / stop pump, default 10*C,
- settable hysteresis (default 5*C),
- during night (6PM - 6AM?) pump "hard-stopped",
- in case of loosing DS readings (during day) - pump starts until readings return (some kind of alarm published for OH2?).
- information about DS readings & pump state published in format readable by OpenHAB2.
- ability to force pump state from OpenHAB (not a "must be").

?

Don't ask for solution but for "what should I read" to do this by myself.

[Philip Knowles]

If you are using openHAB the sensor information is easily incorporated via MQTT as Number items. The same for the pump control as Switch items. You just need to read the MQTT binding page in the openHAB docs.

The information display and on/off control and monitoring is via a sitemap or, possibly in your case, HABPanel.

In my opinion (and I may be alone in this) you are far better doing the control within openHAB using rules there than complicated rules within Tasmota. I would have the main control in openHAB with a 'fall back' rule within the Tasmota device on loss of WiFi/MQTT. openHAB CAN be extremely frustrating but well worth the effort.

One of the keys to success is to write down your control philosophy first. Then look at what you want to happen in the event of failures (as you mentioned about losing temperature readings). Once you have done that identify where is best to implement the control in openHAB or Tasmota and how to alarm on failure. openHAB can email you (or get Google or Alexa to tell you) if there has been a failure. Or you can use them for information. I have a standard doorbell push connected to a GPIO on a Tasmota. I have slightly modified it so I can turn the LED illumination of the bellpush on and off at dusk and dawn and the doorbell sounds throughout the house on Google Home Hubs.

Regards

Phil K

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From: sonof...@googlegroups.com <sonof...@googlegroups.com> on behalf of Laurentp <wyszk...@gmail.com>
Sent: Tuesday, April 28, 2020 6:46:13 PM
To: TasmotaUsers <sonof...@googlegroups.com>
Subject: What Wiki topics should I read to realize differential (solar) thermostate?

 

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[Laurentp]

Hi Philip,
I find single uC solution far more reliable than 2 uCs (Tasmota + OpenHAB on ARM). And here reliability is the key, as not starting pump during good sunlight conditions lead to boil solar fluid. And starting it during ex night at winter (with ex -20*C outside) will freeze water in the tank.
So I want control to be done entirely on Tasmota / Sonoff, OpenHAB for visualisation / remote manual control.

For now I have configured 1 Sonoff + 1x OpenHAB, but OH setup seems to be wrong -> there is no sign of missing comm between Sonoff and OH, but readings in OH are outdated. Even after OH reboot. Moreover I configured fllorplan, but in WWW some rooms show in Polish some in English, in Android app it shows correctly.
So I have now a fresh installation of OH on 2nd OrangePi, and for now only configured MQTT broker.
Now I want to read, what SHOULD I do to get result I want.

[Philip Knowles]

The default teleperiod is 5 minutes so your results will always take 5 minutes to update. Can you send what your items are for the sensors and switches and I’ll see if I can spot anything wrong.

I personally would go for overall control from openHAB and only ‘emergency’ control in the Tasmota device. Some devices work fine for months then do something screwy. If you lose a rule or time synchronisation for some reason you lose control in Tasmota. In particular you can use the weather binding to give you a good approximation of the sunlight/temperature in your location and can control from openHAB if you lose contact with a sensor.

 

Regards

 

 

 

Sent from Mail for Windows 10

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