A steam system

A steam water-heating system 100, the steam system comprising: a heat exchanger 12 configured to heat water with steam; a steam supply line 18 supplying steam to the heat exchanger; a condensate line 24 receiving steam condensate from the heat exchanger; a water supply line 30 to the heat exchanger; a water discharge line 36 receiving heated water from the heat exchanger. There are steam 40 and condensate 42 valves disposed on the steam and condensate lines respectively. A first sensor 44 may be disposed between the two valves to output a pressure signal. A second sensor (48, figure 2) may be located at the condensate outlet to output a condensate temperature signal. A third sensor 46 may be disposed on the water discharge line to output a water temperature signal. A controller may control the steam and condensate valves based on the sensor signals. A method of controlling the system and designing the system are also claimed.