Having some pump problems (a chugger: overheated, erratic sound and output) while using PWM feature (Leonardo with Dragino Yun shield). Everything works great without PWM. I have ACEL brand of above-pictured SSR. Digging a bit I find there are four types of SSR (synchronous or zero crossing; asynchronous or instantaneous; phase angle; burst-fire). I believe the above-pictured and what I purchased are good for resistive heating loads, among others, but not pumps. Does anyone know which type will work for chugger pump motor?