TECHNIQUE On-board heater: where and how to install it (and how much it costs)

Everything you need to know about installing an air heater on your boat, told with a “type” example

The Airtronic D5

The Barcolana may have been canceled, but between the cold, humidity and bora, it’s a good thing we had installed the heater on board!” Speaking is Lorenzo Covini, general manager of Eberspächer Ltd. The company supplied the Dufour 525 24 thousand Kisses (14.99 x 4.60 m) with one of its flagship products, the 5500 W Airtronic D5 air heater: a solution that allows the boat to be experienced 365 days a year.

It’s king below deck when it’s freezing outside, and for those who race, counting on a good heater is no small “plus” when it comes to drying oilskins, sails and gear. We contacted Guido Ramani of Calligaris Naval Electronics of Trieste, who oversaw the installation of the Airtronic aboard 24mila Baci to let us tell you all you need to know when deciding to fit an air heater aboard a 15-meter so that the work is done properly.

Click on the image to enlarge it


First, a good installer goes aboard the boat where the heater will be mounted to survey and figure out the right place to house the machine and budget for ‘custom’ supports and modifications so that he is not unprepared when work begins. Often the drawings provided by the shipyard of your boat do not take into account many modifications made to the hull (especially eye if you have purchased a used boat).”


Generally, the heaters are mounted in the stern locker so that they are close to the diesel tank from which they draw fuel, while at the same time they can easily take in air to circulate below deck outside. You will thus avoid bad smells or the spread of harmful substances below deck (for example, how often does it happen, in a locker, that a fuel canister leaks). The added advantage is that the stainless steel exhaust pipe (in which will have to be well protected by an insulating material to prevent high temperatures from damaging the parts of the boat in close contact with it) does not encounter any obstacles and can be easily directed outward by drilling a hole in the hull“. It may be the case that, as happened in the case of the Dufour 525, “modifications to the dunnage are needed so that the 90 mm tubes can pass easily under the beds.”


Since the heater develops a flow of hot air based on its output, the path of the tube below deck will have to be designed with some important factors in mind. For example, “the shorter the pipe route, the more efficient the system will be. Excessively articulated and extended circuits will result, especially toward the end of the path, in back pressure that will prevent hot air from escaping from the last prepared vents. Linearity should be favored the pipe bends should be very wide“.

In the case of a medium to large boat, where an articulated distribution will have to be made, a restriction of the tube will have to be made: this should not be arbitrary, because it would be equivalent to narrowing the outlet of the heater itself, causing it to overheat. It will be necessary to intervene with a “Y” or “T” joint (Eberspaecher really provides so many options in this regard) and, for example, branch the 90-mm pipe into two 75-mm pipes, at least one of which ends in a nozzle.

Careful not to overdo the vents: too many vents will cause those at the end to be inefficient.

Two final pieces of advice: “Check often that the heater exhaust muffler, if it is outside, is not obstructed by lines and fenders. Finally, do not forget that all components that develop heat (exhaust pipes, hot air) should be kept away from electrical cables“.


The installation of an air heating system, on a 15-meter, will take approximately 30/35 man-hours (after inspection and fabrication of custom components). Estimating labor at 50 euros per hour (as indicated in the refit dossier from page 54), you should get by with a little more than 1,500 euros, to which the cost of materials should be added (The Airtronic D5 model with the basic control costs 2,967€, excluding accessories, vents, pipes). In a nutshell, for 5,000 euros you will have a “top” heater on board that will allow you to experience your boat at its best even in the cold!

Eugene Ruocco



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