I am replacing a 220 volt Intermatic pool timer with a new one where the timer motor will work on 120 or 240 volts.

The other loads are dry loads that will handle either voltage.

I have 240 volts line going to sub panel which has a black, red, and ground wire (no neutral). This is the same wire that I had hooked to my 240 volt timer that I am replacing.

Problem is: I want to wire the new timer up as follows....

Wire timer 120 volts and the pump and cleaner as 240.

I did this by installing 2 double pole breakers for the pump and cleaner and a single pole 120 volt breaker for the timer.

The problem is the GFCI trips when I turn on the power to the 120 volt timer. Is that because there is no neutral wire for the line?

If I change this and wire the timer as 240 on a double pole 240 breker will that cure the problem?

Thanks