Ventilation fridge area (or your solar panel inverter at home) 2024 04 04
The refrigerator in our boat is built into a cupboard in the salon. Because the salon gets quite warm on sunny days, I want to ventilate the fridge 's cupboard from below with colder air from the tank room just below the fridge.
During the Summer and daytime the air below the fridge is kept relatively cool by the (in this area) non-insulated ships hull. There's also an open connection with the air outside, via the engine room's air intake.
The movement of the air is done by two 12V computer fans with a diameter of 12 cm. They are connected in series, each at 6 V, so they run more quietly and produce less noise.
To prevent the entire floor from becoming a sounding board, I sawed 2 square holes of 13 x 13 cm in the floor and placed the fans, clear from the wood. They are mounted in the corners in rubber forks. (cut from sheet rubber)
To make it possible to start the 12 V fans, with only 6V, I placed a capacitor parallel (one for each fan).
The position of the openings in the floor, is at the back of the refrigerator, halfway underneath the cooling rack.
Because the fans are only needed in warm conditions, I switch them via a temperature-controlled relay which is set to 25° during the summer and 20° at cooler times when I want to use the produced heat to help warm the cabin.
Sensor and relays
The temperature controlled relay can be adjusted/set with the 3 black push buttons. (From left to right: SET, + and -) The temperature sensor is connected at the top right with a small plug.
It is important that the power supply voltage doesn't exceed 12 V. Because this happens while charging the batteries, I use a DC-DC converter that keeps the voltage at 12V. (You can also use a smaller stabilizer like a 7812, but the converter was already present)
The circuit board with the relay, is (insulated) mounted on an aluminum bracket above the refrigerator. It can be read and adjusted/set there. The power is supplied by the DC-DC converter. This power supply is powered from the 12V connection on the back of the refrigerator and turned on / off with the switch on the aluminum bracket. The refrigerator itself is switched on/off at a switchboard (3.3) next to the steering position.
The temperature sensor is placed high in the refrigerator room (see photo)
Before placing the display, consider if you also want to use its red glow to help you find your way at night (to prevent spoiling your night vision.)
This diagram below shows the switching method.
Result: We are happy with this setup and the sound is not disturbing.
If you are considering a similar setup, it may be worthwhile to verify first that the air you are going to direct to your salon space smells clean enough. We keep our engine compartment and bilges clean and dry. However, my experience has taught me that this is not always the case in other boats.
The setup above can be simplified by using only one fan.
Cooling a solar panel inverter at home.
Our solar panel inverter at home is build in tight and doesn't have it's own fan. The charging will switch off when it gets too warm.
Cooling the inverter with an external fan when the temperature rises above 30 degrees increases our energy production.
In this case we use the same type of relay with a single fan, powered by a 6 volt adapter.
Note: Cold weather improves the output of the solar panels and will cause your inverter to produce more heath. So the extra cooling of the inverter may be needed during cold weather as well.
Jeroen Droogh
bootprojecten@gmail.com