Harvia Black Legend Pipe Mounted Water Heater TankHarvia's innovative designs do not fall short with the WP250LD, crafted to heat the water as efficient as possible. The front of the water heater is covered by stones so when water is thrown on them it gives your sauna more steam while helping to heat the water. The water heats up quickly because the pipe going through the tank functions as a wall of the water tank. Safety is always a top priority and with the new tap solution its safer to work with