For example, it can integrate a solar heating loop to supplement the gas heat. And the 55-gallon tank is super insulated, losing just a half degree per hour. But the boiler is a whole-house heating system, plus a water heater—producing up to 314 gallons of hot water in an hour at 96% efficiency. The 135,000 BTU boiler can supply baseboard heat at the same efficiency. www.htproducts.com