The [Vaillant uniSTOR VIH R 120/6](%id:689280%) does not have an electric heating element; it uses an indirect heating method with a heat exchanger. However, you can do it with another modification of this product, such as the [Vaillant uniSTOR VIH R 150/6](%id:689307%) or [Vaillant uniSTOR VIH R 200/6](%id:689314%), which may offer different configurations that could support electric heating elements. [The response is based on the specifications of the Vaillant uniSTOR VIH R 120/6, which indicates it uses a heat exchanger for heating rather than an electric resistance. The mention of other modifications (Vaillant uniSTOR VIH R 150/6 and Vaillant uniSTOR VIH R 200/6) is to suggest alternatives that might have different features. The data was sourced from the product specifications available in E-Catalog.]