Water heaters with dry heater

Dry heater

— it is a modified version of a conventional heating element (see the relevant paragraph), equipped with an additional protective shell — most often metal, with an enamelled surface. The space between the heating element and this shell can be filled with both air and a special material — for example, quartz sand or oil. Anyway, the heating element itself does not come into direct contact with water, which provides several advantages. In particular, heating is safer, the probability of insulation breakdown is reduced, and the scale on such heaters almost does not form, which allows them to be used even with hard water. However, dry heating elements are noticeably more expensive than usual ones.