Replacing the roof hatches with MAXXFAN fans

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Aktualisiert – Juli 21, 2024

The conventionally installed roof hatches, some even with built-in fans, serve to ventilate the interior and are sometimes provided with fly protection and even sun protection roller blinds.

The disadvantage is that when it rains, you should always close it to prevent driving rain from getting in.

If you want to be on the safe side, consider the roof hatch ventilators MAXXFAN recommended. They fit into the specified roof cutouts of 40 x 40 .. 42 x 42 cm for roof thicknesses of 25 .. 90 mm and can remain open even when it rains.

The opening can be controlled manually, electrically and automatically depending on the temperature, as well as by remote control. The speed is also infinitely adjustable and the direction of rotation can be switched (ventilation / venting).

There is an approximately 5 x 5 mm aluminum grid on the outside to protect against leaves, etc., and on the inside there is a removable metal fly screen.

MAXXFAN electronics

The electronics are housed inside under the fly screen insert and, in the event of a defect, can be easily replaced by loosening four screws thanks to the plug-in connections for all cables. The fan can also be removed from the inside, as can the motor that raises and lowers the roof hood.

At the lowest speed setting, the fan cannot be heard, but it ensures a constant exchange of air. At high speeds it can certainly be used as an effective extractor, but then it is also just as noticeable.

Roof cutout too big?

If the roof cutout is too large - too small is not a problem... you can cut (or have) a piece of approximately 6.. 10 cm overlapping edge cut out of 4 mm HPL board or 3 mm aluminum sheet, which is suitable for the fan Make a cutout and glue the resulting frame onto the outside with Sikaflex adhesive so that it is joint-tight.

Inside you can work with a similarly manufactured frame made of (also colored) 3 mm acrylic glass frame, which can also be attached with assembly adhesive, while the cover of the MaxxFan can be glued on with silicone.

Why not with glue too? Because silicone can be easily removed if necessary and you have plenty of access to cabling or MAXXFAN as such.

Replacing the roof hatches

Replacing the old roof hatch is relatively easy. The most difficult thing is to completely remove the often used Sikaflex adhesive on the roof. The inner part can be dismantled by loosening just four screws.

I personally prefer the installation with transparent silicone, as it is just as tight but easier to remove. After about three quarters of an hour, remove any excess silicone from the roof membrane using a spatula held parallel to the roof at an angle of about 45°. The “sharp” side of the spatula is used to “cut off” the silicone on the edge of the roof hatch surround. This is how you avoid silicone smearing on the roof.

As a rule, the roof hatch is installed with the end, which is raised when open, facing backwards. However, if there is a lack of space, the roof hatch can also be installed across the direction of travel. However, the hatch should then only be slightly open when driving in the rain to prevent rain from getting in.

Power supply for the MAXXFAN roof hatches

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The supply line can, for example, be routed from one roof hatch to the next through a hole in the roof insulation made with an approximately 50 cm long 12 mm formwork drill. With a little imagination and research, you can find a way to get 12V in almost any position.

Voltage stabilization

Unfortunately, since Maxxfan has not installed any voltage stabilization to protect the electronics from overvoltage (as can occur when charging via an alternator), it acknowledges that it has failed in its service, i.e. it has died. If this happens during the warranty period, you can complain and exchange the new electronics for the defective one (see below). But it is better to take precautions by having one DC/DC converter 12/12V which takes over the task of overvoltage protection.
Please note: the DCDC converter should not be able to supply less than 5 A load, as the fan has a current consumption of 2.7 A at full load.

Replacing the electronics

First, the ventilation grille must be released by unlocking the four rotating retaining lugs. Then unscrew the four Phillips screws that hold the entire lower part to the upper part. The electronics are also attached with smaller Phillips screws. Before these are loosened, the cable connectors must be separated. Now the small Phillips screws can be loosened, the electronics can be removed and exchanged for the spare part.