Thermostat issue

[C4RVA]

I'm having an issue with a furnace giving an " external load on w" error when I use a control4 thermostat. The furnace works correctly when switching back to the cheap honeywell thermostat. The unit will allow the control4 tstat to control the fan and ac as long as the white wire is not connected. I think there may be an internal fault with the thermostat. I have the same results using w1 and w2 for the white call for heat wire. Any ideas?

[C4RVA]

So the fix for this was to use a 24vac relay on the white call for heat wire. The thermostat was wired to control the relay coil and the call for heat was wired to the NO switch. This seems to keep the furnace happy. Its worth noting that a solid state relay caused the same error with the furnace and a mechanical one did not. Seems the furnace is expecting just a plain old switch and nothing else.

[esmadja]

I wonder if my issue is related.

When I installed my c4 stat my fan would turn on and never turn off.

I did a 15x center button and 9-4-9 factory reset.

On my old stat when it was off the connections between w and g are open. On the c4 stat the connection between w1 and g is closed. This connection only opens when the connection between wi and rh closes.

I think as a result my fan never turns off

Ay idea what could be wrong.

Thanks,