Hello there

I've got to switch an AC load through triac. have only 8Ampc apacity
(BT 139) .
is it possible to double the capacity by connecting two in parralel?
appreciate your help. the triacs are used only as On- off switch no phase angle no control is needed. just to short the MT1 with the gate.

 

It's unlikely to work, as one will tend to hog current and heat up. Use a relay or a triac with some excess capacity.

 

Or...look into current sharing methods for paralleled bipolar transistors. Beyond the bipolar analogy, I suspect you might have some problems getting both Triacs to turn on at the same time.