During DHW operation, the boiler temperature is normally raised above 180°F (82°C). Once the DHW tank is satisfied, the residual heat from the boiler may be wasted if there is no other call for heating. This residual heat from the boiler should be purged in order to reduce standby losses. This is accomplished by turning the boiler off but keeping the DHW pump or valve operating for a purging period. This function increases system efficiency by decreasing boiler losses.