HYDROTHERM HW Series - HW4 Model - Hydronic Towel RailHydronic Heated Towel Rails provide warmth in the same way nature does by natural convection and radiation. It does not dry out the air by burning or cause unpleasant draughts, hot spots or noise. These towel rails are only viable for use in Hydronic, or Circulated hot water systems. Width: 400, 500, 600, 700, 800, 900mm Height: 1720mm + Valve Connection High Polished Chrome Output: 0. 90 1. 15 Kw Technical Specification