10 important questions to ask before you install engines in your vessel.
You will find this information in the detailed specification of your engine. Alternatively, the supplier will provide you
with factory data prior delivery. JEC will be only too happy to help you select the right air supply fan. JEC has provided fans
for many types of engines and has additional data resources.
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JEC provides three standard sizes: 300, 400 and 500mm in diameter. The larger the diameter you can fit, the more efficient and less noisy will be the operation.
We recommend the largest air inlet possible in order to increase the efficiency of the fan combined with the reduction of
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Our fans operate from DC supply 24V nominal (the typical operating Voltage from alternators of 28V DC is ok) and are specifically designed for maximum performance at this Voltage.
The smallest fans in our range will require maximum current of 18A, typically around 12A. Our largest fans will take up to 50A.
Our fans employ brushless technology with powerful rare earth magnets, resulting in a reduction in size and hence the profile, which reduces drag of the system.
Typically, our brushless DC fans’ reduction in size is about 50% compared to that of single phase 240V AC/50Hz ones.
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Our air supply fans operate from DC Voltage 24V nominal (28V DC operational), eliminating the need to run an AC generator. This translates into saving fuel and maintenance costs.
For older DC systems operating from 12V DC, we can supply a 12 to 24V DC marine booster that is set to the optimal and stable operating Voltage.
The best place for the inlet is that part of the boat which has the least amount of sea spray. Our air supply fans are designed to withstand continuous sea spray and will operate without corrosion over many years. However, you need to limit the amount of salty particles entering your engine room for the protection of other equipment.
There are a number of various filtering systems that will protect the engine room from the salty sea spray. This is at the cost of air flow volume. The positioning of the air duct entry is vital to reduce the need for filtration. The air entry duct is best placed on the fly bridge facing the front of the vessel. This gives a natural air flow when anchored. The vessel will always face into the wind and will provide ample of air flow without the use of additional forced ventilation.
We can construct a custom made fan on request upon consultation with you. The advantage of our construction over the classical AC fans is that our DC fans are not bound by the 50 or 60Hz frequency. The only way AC fans can maximize their air volume is to change the pitch of the blades, if this is actually possible.
Our DC fans however, in addition to varying the pitch, can also vary the speed and can be fine tuned to achieve optimum performance and hence increased efficiency.
The fans also have soft start and can be ordered with manual or automatic speed control, based on a number of factors, i.e. engine room temperature combined with the speed of the engines.
The smaller the diameter of the inlet, the more noise will be generated. For any particular installation we can make a theoretical calculation of the expected noise.
The speed control on our fans virtually eliminates the bulk of the noise due to the fact that the vessel very rarely operates at full speed and therefore maximum fan speed. In that situation the noise of the waves and of the engines is greater than that of the fans. At normal operating conditions or trawling, fans without speed control can become very noisy.
AC single phase motors are not designed to operate much below the 50Hz frequency and often overheat or burn out.
A.-10 Should I install an air supply fan, or an air extraction fan, or both?
Using both, an inlet fan and an exhaust fan and controlling these correctly with different boat engine speeds is virtually impossible. It makes as much sense as using a propeller each end of a vessel. With appropriate exhaust ducting and outlets, a single inlet fan will perform perfectly.