HVAC automation across sources

Configuration
1

So, my house has baseboard hot water heat, heated with an oil boiler. I also have two minisplits.

In the summer we only use the minisplits for cooling, but now that the cooler months are coming I’m trying to figure out the best way to automate the heating part of it.

Oil is going to be more expensive and less efficient than the mini split, and what I’m looking to try to accomplish is to have one place to set the temp, and then that can do some logic in the back end, to see what the outside temp is (since the minisplit gets less efficient as it gets colder outside) and depending on the outside temp, use the baseboard heat, or the minisplit heat.

2

Use the generic thermostat template to create the entities that you will set the desired temperature. The generic thermostat operates a switch. So then create a switch template that calls scripts that manipulate the thermostats for the splits and/or baseboard heat. My guess is mostly you’ll be adjusting the setpoints rather than toggling the hvac mode. You don’t want to be in a situation where your logic fails and you leave both the splits and the baseboard in off mode. Perhaps just setting the one you don’t want to use down (e.g. 55 degrees) and then forwarding the generic thermostat setpoint to the one you do want to use. Simple and reliable.

3

Yah, I did look at that, I didn’t understand how to have multiple sources underneath one generic thermostat.

4

Just updated my comments.

1 Like
5

Thanks, gotta wrap my brain about that one.

I’m not too worried about them both “failing” because the oil thermostat is a Nest and has a safety mode so something like that doesn’t happen.

6

I’d also need something to check the outside temp periodically. I wouldn’t want the minisplit on, and then the temp to drop where it’s no longer efficient and not switch to the oil boiler.

7

I have a NEST every now and then it drops setpoints. To make it reliable, I’ve had to implement a retry mechanism. I can share that once you are at a point where that is needed.

8

I have a similar set up. Two mini splits one on each floor and one gas boiler for both floors. I made a NodeRED flow to automate this, this is how it works:

  1. Two seperate thermostats for each floor, one for setting the heating temp, and one for cooling temp.
  2. If at night the temp of heating is automatically adjusted do -2 degrees C then the set temp.
  3. For away mode there is a -3 degrees.
  4. AC for cooling is off if its less then 18 C outside
  5. AC i heating the house if its more then 5 C outside
  6. If less then 5C outside the heating switches to gas unless my PV is working then I use AC
  7. If there is no one on one floor the gas heats up to ~18C and to get to the set temp where there are people I use AC unit.

For now I have tested it in a limited fashion, since I do not need to heat the house yet. But it should work as planned. Here you have my flow: https://easyupload.io/462jjb

9

I was hoping to avoid Node Red. I moved all my node-red automations to internal HA’s automation, but I’m thinking this might be the only way. Thanks for this, I’ll check it out.