Air Handling Unit interval Fan control

Hello all. What a great forum this is. There are tons of useful information here but I could not yet find the answer to my problem. Maybe somebody has a good idea.

The following I try to achieve: I have an Air Handling Unit with a heating coil inside it. The fan of the AHU is a always on. A normal (non-z-wave) room thermostat switches on the heating boiler supplying then warm water to the heating coil in the AHU.

My idea is switch the AHU fan on/off via an interval timer to save energy. The fan should be always on when the supply temperature to the heating coil is above a certain set temperature (SP). When the temperature is below the set temperature (SP), the interval timer should do its work (switching the fan On and Off). The following conditions are applicable:

No. Supply Tem Function Interval timer Fan
1 >SP OR True On
2 > SP OR False On
3 =< SP OR True On
4 =< SP OR False Off

I have installed the App PLEG and PLC and used the logical OR function with a temperature sensor point and an interval timer, but somehow it does not work.

The logic, interval timer settings and logic details are here:



t1TemperatuurSensor is set to give a True when the temperature goes above a set temperature.
s1IntervalTimer is set as a regular timer (in the picture it is set as an interval timer 1:01 on for testing purposes, but the final setting will be something like 20 mins On and 20 mins Off)

In the logic block c1TempORTimer is an OR function with the variables t1TemperatuurSensor and s1IntervalTimer. On this basis I switch the ePlug_Schakelaar On or Off (set 1 or set 0)

Somehow this does not work. The interval timer is very irregular and I cannot find any pattern or logical reason why this does not work. :-\

Materials in use:

  • Vera Plus
  • Fibaro Universal binary sensor with temperature sensor
  • Smartplug

Anybody any idea…?

you may want to move this to the programming\pleg sub-forum. This is a pretty specific feature that might require one of the power PLEG users (and Richard) to solve.

You really need to post your STATUS report in PDF format (plenty of free PDF printers).

Dear all, thank you for your help. Herewith the Status Report - hope this helps.

Posted this question now in the programming section

Two Problems:

  1. Condition should be:
    t1TemperatureSensor AND s1IntevalTimer

  2. You only have the timer ON for 10 seconds, but it never turns Off
    You want something like ON Every 30:00 (thirty minutes) and OFF after 15:00 (fifteen minutes)
    This will be on for 15 minutes of every 30 minutes.

Thx Richard!

I completely misunderstood the functionality of the timer ::). Now I understand that you need to set an ON and an OFF time and that the ON time should be set overlapping with the OFF time (the latter part I did not understand). I have set it as attached and it works perfect! (as example with 5 sec on and 5 sec off)

However I do need the OR function in order to make it work as needed. Thank you very much for your support! :slight_smile: :slight_smile:

P.S. Is there somewhere some a manual of this…? I could not find the timer functionality in the ‘basic manual’

Which branch would you say has the best benefits for Air Traffic Control?