The Nasgas SEM-121 is a semi-instant electric water heater designed to provide hot water on demand with moderate storage capacity. As a “semi-instant” model, it provides a balance between pure instant and fully stored water heaters. It boasts a 12 L capacity, and uses up to 1,500 W electrical power. It is built for standard domestic supply with a working pressure rating of 0.8 MPa. 

Safety and durability are important in this model. It includes dry-heating protection (cuts off when there’s no water), over-temperature protection (triggers around 85 °C), statutory safety valve rated at 0.8 MPa, and earthing protection to reduce risk of electric shock. The outer body is made of plastic, offering corrosion resistance. 

In summary, the SEM-121 is a good option where you want faster warm water than a full storage geyser but still have some buffer capacity. It’s suitable for bathrooms, kitchens, or small homes where demand isn’t extremely high.