3 in. x 48 in. Drain Water Heat Recovery UnitAt 20 30% of home energy consumption, water heating is typically the 2nd highest energy demand. The Power Pipe can dramatically cut water heating costs and reduce total home energy consumption by 5 10%. It works by using outgoing warm drain water to pre heat incoming cold fresh water so your water heater doesnt have to work as hard. The Power Pipe will typically pay for itself in as little as 2 years, and may qualify for Government or Utility grants.