overkill tea timer (turns heater off)

[grifftech]

What do you think? is it ok to connect a contactor like this?

[Ian.M]

Looks like gratuitous overkill.   If its a 40A contactor with a 15A load, why would you parallel the contacts?   

Personally, I'd switch Line and Neutral, leaving one contact spare.

Also, what's going on with the over-complex MCU power and contactor control circuit?
What's the contactor coil voltage and current and is its coil DC rated?   Assuming its AC rated, If it uses a low voltage, then you can probably use a sensitive gate TRIAC driven by the MCU to control it, and unless the MCU needs a lot of current from its 5V rail, half wave rectify the control transformer secondary then regulate that down to 5V to supply the MCU.    If it needs lots of 5V current, you'll need a bridge rectifier and a buck converter to get the 5V, and an opto-TRIAC between the MCU and the TRIAC.   If its DC rated, go with a bridge rectifier to feed the regulator or buck converter for the 5V coil, and a logic level MOSFET to switch the raw DC to the coil.

[drussell]

Wait, you're using 120A of contact to switch <15A of juice?