Creating nested conditionals in the ISY994i

Reader Jimmy wrote in with the following suggestion (apologies for this coming as Spring is upon us, but the takeaway for nested conditionals in the ISY994i is relevant year-round!):

Now that it is winter and humidity control is needed how about a blog on that? Here is my set up:

  • 2441TH Insteon thermostat with humidity monitoring.
  • 2450 IOLinc for switched output for humidifier on/off control
  • AprialAir 800 whole house humidifier (steam in air duct)
  • Climate Module for local temperature (I know I could have a thermistor input for local temp but I use the Climate Module for irrigation control also)

So I have it programmed that if house humidity is less than 45% and the heat is on and the fan is on (I run fan continuously) and the outside temperature is < 40 degrees the humidifier is turned on. This works great until the temperature drops below 30 degrees then the windows sweat up. I do not know how to do nested If-then to create a program that follows the recommended humidity settings to avoid this.

  • If temperature outside is 30 to 40 degrees and humidity inside is less than 45% then turn on but…
  • If temperature outside is 20 to 30 degrees and humidity inside is less than 35% then turn on but…
  • If temperature outside is less than 20 degrees and humidity inside is less than 25% then turn on.

Anyway a blog on the above application or how to do nested if then would be great.

The answer to this one is pretty simple – in the ISY UI, there are these somewhat hidden buttons in the bottom right corner of the program window that allow you to add “ANDs” and “ORs”. Simply click either and use the “Move Line Up” or “Move Line Down” buttons to group the conditionals together. Here’s an example where I’ve done a complex conditional in the ISY for turning on lights for a period of time when motion is detected – but only if it’s after dark and only if the lights aren’t already turned on at full level:

With this specific application, though, I advised Jimmy that he probably doesn’t even need complex nested conditionals – just multiple programs that match the specific criteria here’s looking for, similar to the following:
So he’d have three separate programs like this for each of the above criteria, and only one would run at a time as the temperature and humidity fluctuate.

Posted by Matt Chiste
March 22
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