In the tropics, or where there is limited electricity or no electricity or very high energy costs, they may use the Passive PT without a backup water heater tank see Direct System The ProgressiveTube makes hot water, and if it runs out, they go without. The PASSIVE System ProgressivTube is IC ...
The PASSIVE ProgressivTube Passive Solar Water Heater outperforms other systems - even in colder climates. The best suited solar water heater systems for northern climates are the Active Closed-Loop and the Passive Systems. Research has shown that the Passive ProgressivTube is the most cost effe ...