Very happy with it. Used it 2 times so far. Heavier duty and bigger than I expected. Shipping containers were solid! See pictures. My detailed experience below: Since I have it connected to a filter pump, I’m not using it as it’s thermosiphon designed, and pumping water through the coil, rather than natural thermosiphon. The first test was with full filter flow through the heater. The second test was with restricted flow. So far I’ve raised my 700 gallon / 8 foot stock tank from 67°F to 79°F in about 3.5 hours, which works out to about 5.7 kW of heat into the water. The heater is advertised as being equivalent to a 10–15 kW electric heater. I’m currently installing a bypass loop so I can keep full filter flow while adjusting the flow through the heater to see if I can improve performance.