Fan On setting not working

After quite some time spent with random reboots and sluggish response I have gotten my HestiaPi Touch One up and running. I like to keep the fan on the furnace running even when the heat is off which I presume is the Fan “On” setting. (this was what my old thermostat used) Once the furnace reaches heat the fan goes off whether set to “Auto” or “On”. The fan symbol on the screen does change to throbbing while heat is on and remains throbbing when set-point reached and heat goes off.
My furnace does support this as this is how I used my old thermostat. Thanks in advance for your help.

That is strange… Assuming you have the HVAC model, please try the following (you would need a multimeter with AC voltage measure range covering 24V AC):

  • Turn HestiaPi off from the Maintenance menu of the App or WebUI and wait for the LCD to go white first and then the LEDs inside the case to stop flashing.
  • Turn power off from the circuit breaker so that the LCD is now off
  • Pull cover off
  • Remove LCD from cover by sliding to the right, rotating anti-clockwise and pulling making sure you are not forcing the plastic hooks too much.
  • Pull MicroSD out (to prevent accidental boot)
  • Insert LCD by hand on the LCD socket very carefully to align the pins correctly. Please note the male socket on the PCB has some slack. The LCD female header should aligned in the center.
  • Restore power from the circuit breaker
  • Insert MicroSD and press the reset button on the right side
  • Wait for the boot to finish
  • Turn fan to ON mode (leave heating OFF)

With the contacts on the HestiaPi’s terminal block referenced like so:

Confirm the following measurements (format Probe 1 Position-Probe 2 Position:Expected AC Voltage in V):
C-R:24
C-G:24
C-W:0

  • Confirm the fan turns on.
  • Turn heating ON

Confirm the following measurements while the furnace is running:
C-R:24
C-G:24
C-W:24

  • Wait for the heating to reach the temperature and confirm

C-R:24
C-G:24
C-W:0

After the test restore normal operation like so:

  • Turn HestiaPi off from the Maintenance menu of the App or WebUI and wait for the LCD to go white first and then the LEDs inside the case to stop flashing.
  • Turn power off from the circuit breaker so that the LCD is now off
  • Remove LCD and re-insert on the cover by following the steps in reverse.
  • Restore cover
  • Restore power from the circuit breaker
  • Wait for the boot to finish

Please report

With the heat off and the fan on, I get:

C-R: 24
C-G: 0
C-W: 0

However, I also get:

R-G: 24
R-W: 24

which seems very odd.

Hmmm… there is a (high) chance you are measuring “ghost” voltage (not sure this is the right term). If you have a 24V AC load like a light bulb of power less than the max the furnace can provide this would be best for confirming presence of 24V AC.
I’m not sure if it is possible as you say your HVAC works more or less, but is it possible C and R to be swapped?

I swapped the C and R wires and the Pi does not receive power to boot, so not the problem/solution. Ideas, I feel that due to the unique problem this unit is somehow defective. It also has the common screen problem. The cursor shows up when touched but not at point of touch and as such cannot be operated from the screen.
please advise,
Paul

Follow the LCD wiki instructions


And disable the startup script so that the browser (HestiaPi GUI) does not kick off at the beginning and select the calibration tool from the LCD main menu to get the numbers for your screen.