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Water Heaters / Calorifiers

Water Heaters / Calorifiers

Boat water heaters or calorifiers (as they are also known), provide hot water on board. They work as heater exchangers, deriving their heat source from the boat’s engine cooling system. All our calorifiers are fitted with 230v electric immersions heaters allowing you to continue to have hot water when the engine is off and you have a source of either shore power or battery power via an inverter.

Isotemp / Isotherm part of the Domestic Group, make this quality range of stainless steel, marine grade water heaters. All Isotemp water heaters feature a thermo mixing valve which protects against scalding water and helps maintain hot water efficiency and conservation. There are four models of calorifiers in this range - Isotemp SPA, Basic, Basic Slim and Slim Square all of high quality and well worth the investment. The salt water environment coupled with water and heat can be extremely corrosive. Failures and breakdowns can be costly and highly inconvenient when on a cruise, so we do recommend Isotemp as the best water heater or caloriifer range on the market.

So which model water heater should I choose?


This is our first choice for sizes up to 40L. Most economical with all the performance of the other models.


Choose this for sizes above 40L, for spaces with more width and less length and for when you prefer a satin, stainless steel outer finish.


Choose this for special locations and narrower spaces.


Use for either double heat source (i.e. twin engines) or double heat output (i.e. radiators & hot water).