Heliodyne Helio-Pak heat transfer appliance for closed loop solar DHW systems that do not have a tank with an internal heat exchanger. Complete packaged pump station with double wall counterflow tube in tube exchanger, Wilo cast iron glycol pump, and brass domestic water loop pump, fill & purge valves, Heliodyne WIFI control with 3 sensors, pressure gauge, relief valve, & air purger. Expansion tank included. Heliodyne part number HPAK 116-001. WIFI feature allows monitoring of system from your computer.