This heater will not work on the suction or vacuum side of pump (front port).
***This Heater will not function or energize without water flow/pressure. This heater will not function plugged in wall outlet without sensing pump pressure and water flow***
Pump Not Included.
Should you have any questions or comments, please do not hesitate to contact me. I've been servicing the whirlpool bathtub and spa industries since 1983.
Please visit our eBay store for more jetted bathtub components.
Including our Patented Non Electric "Thermal Wrap" Heat Transfer System - Heat Jacket Bathtub Heater.
Thank you for your interest.
Jim