Fan Replacement on Seafrost Refrigertion

[lancelot9898]

I'm replacing a fan on the Seafrost 12 volt refrigeration air cooled system. The fan I purchased is a Noctua NF-F12 model containing 4 wires(a black, blue, yellow and green wire) The fan being replaced has just two wires(a red and black wire). Which of the 4 wires from this new fan go to the + and - posts? I assume the black is the negative so is it the blue, green or yellow wire to the +? Or does it matter? Could more than one wire go to the + post providing more rpm? Thanks for any input.

[Suijin]

Yellow is positive, black is neg.

Remember that fan has a front and a back, so install it in the right direction. If it runs backwards after installation, just switch the wires.

[Richard Kollmann]

Condenser Fan Replacement

It is important that pleasure boat refrigeration units are equipped with fan forced air cooled condensers in order to maintain proper refrigerant pressure regardless of ambient seasonal air temperature changes. Danfoss BD 200 Btu up to 800 Btu compressors are mostly used to power two to ten cubic foot boat refrigerators.

There are several things to consider when replacing a small 12 volt refrigeration condenser fan:
• Correctly designed refrigeration units incorporate a safety pressure device to stop compressor from destroying itself when condenser cooling is less than desirable. Instead of a pressure or thermo switch Danfoss uses an electrical circuit to measure condenser fan performance. If fans amperage exceeds 500 milliamps (1/2 amp) compressor will be prevented from running by a safety override in control module.
• New BD35 and BD50 Danfoss compressors with standard control modules will operate on 12 or 24 volts while condenser fan will remain powered by12 volts.
• Danfoss BD condenser fans are brushless 12 volt DC two wire are approximant 4-5/8 inch square most and one inch thick.
• These fans are referred to as Muffin axial compact fans available in air flow volumes from 30 cfm .17 amps per hour to 130 cfm .6 amps per hour.
• Condenser cooling fans are monitored and operated from a private electrical circuit connected to Danfoss Module terminals small + and F. If amperage in fan circuit exceeds ½ amp compressor will not run. Supplemental cooling fans are sometimes required to remove refrigeration process compartment heat, to add extra load to the fan circuit a relay is required.
• Selecting condenser cooling Fan’s airflow Cfm is important. Most refrigerator manufactures design for installations where standard day air temperatures are 70 degrees F. Mobile refrigeration like those sold to be used on pleasure boats generally are sold with 30 Cfm to 50 Cfm condenser fans.
• Location of condensing unit and climate temperature conditions may dictate fans with higher Cfm capacity to achieve better performance. Disadvantage of higher capacity fans is increased noise.
• Because condenser fans run from 8 to 12 hours a day in warm climates service life is important. Four inch Muffin fans are available from many sources from $12 to $60. In a live aboard boat it is believed that muffin fans with ball bearing on armature rotor will extend the brass bushing bearings units life by two years.

[lancelot9898]

Thanks Richard for the explanation. I think this fan is rated at around 70cfm, but really unsure if maybe there are additional speeds associated with it considering the blue wire. I'm pretty sure it will operate with just the yellow and black wire and hopefully the air flow will be sufficient.

[svHyLyte]

We have an older SeaFrost refrigeration unit for our freezer that was installed by the prior ("original") owner of our boat. Unlike our FrigoBoat unit (for the separate refrigerator), the fan on the Seafrost unit pulls air through the cooling coils rather than pushes/blows it through. While the cooling coils are a few inches from an intake vent in the side of the cabinet where the unit is mounted, the opposing side of the cabinet only has a louvered door where, presumably, the air drawn through the cooling coils would be vented. While this arrangement worked, it was not particularly efficient. In an effort to improve things, this past winter I added a second "muffin" fan to the back side of the exhaust louvers that is connected to the power for the fan on the SeaFrost. When that fan is powered up, the fan on the exhaust louvers also activates, blowing air out of the compartment.

While the power draw of the dual fan arrangement is greater, the additional fan has dramatically improved the performance of the freezer, allowing us to achieve much lower freezer temps; or, the same freezer temps but with reduced operating time per cycle.

FWIW...

[lancelot9898]

Thanks Hylyte and everyone. I installed the seafrost about 9 years ago and it was a self contained unit. The original fan pushed the air through the coils and installing the new fan, I kept the air flow the same direction. This new fan has a higher cfm than the original and for the last 30 minutes it is providing good flow so adding another fan in series will not be necessary. Appreciate all the input.

[Typhoon]

Originally Posted by lancelot9898

I'm replacing a fan on the Seafrost 12 volt refrigeration air cooled system. The fan I purchased is a Noctua NF-F12 model containing 4 wires(a black, blue, yellow and green wire) The fan being replaced has just two wires(a red and black wire). Which of the 4 wires from this new fan go to the + and - posts? I assume the black is the negative so is it the blue, green or yellow wire to the +? Or does it matter? Could more than one wire go to the + post providing more rpm? Thanks for any input.

These are excellent fans , we use a pair of industrial grade Noctua fans in all our systems .

They are not inexpensive, but are rated for 150000 Hrs , and worth every penny .

Regards John.