These isotherm calorifiers quickly and efficiently heat the water tank by using the boats engine water. Oversized heating coils inside the water tanks, allows the total capacity to be heated in 20 to 30 minutes. Heat losses are only 0.5 degrees per hour so there is still plenty of warm water after a night at anchor. Dimensions (LxD mm) + Kg: 24L: 460 x 395 - 11Kg 40L: 630 x 395 - 17Kg 50L: 750 x 395 - 20Kg 75L: 1040 x 395 - 26Kg