Although a thread was started on this subject, it really belonged in this section. I am going to describe and attach pics showing how I totally FIXED the noisy fan issue and actually improved airflow at the same time.
Using SilenX fans (
www.silenx.com), I created a new refrig cooling unit that utilizes 2 of the 120MM 11DBA fans. I purchased mine directly from SilenX for $55.75 including shipping. These fans are large volume, high efficiency fans with quiet blade technology. They also come with silicone mounts to further isolate any noise produced.
My goal was to eliminate BOTH inside AND outside noise as both were major issues with my '02 Bambi (shared with all recent models lacking roof ventilation for the refrig).
In designing my new cooling system, I made a significant change from the original design in that originally, the fan mounted vertically and PULLED air thru only the center 4" of the refrig condensor. The design of the outside door greatly restricted the airflow exhaust plus it forced the air downward where it could be immediately pulled back into the lower louvers of the vent and circulated back thru the condensor (ie a hot air short circuit). In my new design, the fans are mounted BELOW the condensor and PUSH air thru almost 9" of the condensor. I also eliminated the potential for the hot air short circuit by blocking the section of the upper access door residing below the fans (ie incoming air NOW is pulled from the lower door which is about a foot lower). All of this will be clearer in the pics.
As I was installing 2 fans, I also added the ability to run them either in series or parallel (electrically speaking). Running in series, they run quieter while still moving significant amounts of air. In parallel, I have max cooling and very acceptable low amounts of noise.
Results...FAR better than anticipated. Even when running full speed (ie in parallel), the fans are virtually silent. You have to put your ear DIRECTLY against the upper door louvers to even hear anything. In series mode (half speed), there is simply ZERO noise...PERIOD. Inside, running full speed in parallel mode, you can barely hear a slight noise, BUT it is MUCH quieter than even the Magnetek converter fan. In series mode, NOTHING inside or out.
Okay for the details. I purchase aluminum angle stock, aluminum bar stock and aluminum sheet stock at Home Depot.
Using the aluminum angle stock, I made two brackets that actually hold the fans. I cut away the section of the aluminum that would otherwise have blocked a section of airflow on both fans. Using the included silicone mounts, I mounted each bracket to the fans. As the two brackets are NOT attached to each other and the silicone mounts are very flexible, I also made small brackets that mount on the top of the fans as well as the side aluminum brackets. This provides rigidity at the expense of some of the noise isolation capability of the silicone mounts (minor).
Using the aluminum bar stock, I cut a length the width of the upper door opening and riveted it to the fan assembly backets already constructed. This acts to support the front edge of the fan assembly. I also cut another section of bar stock and bent it to form a support going vertically from the backside of the fan bracket thru 2 bends such that it arrives at the same plane as the solid bar attached previously, but several inches lower. This bracket acts as the rear support for the fans. The fans do NOT touch the refrig at ANY point as this could allow noise to transmit thru the refrig to the inside of the trailer.
The final additions were some baffles to direct the airflow more precisely. The new fans, being slight wider than the condensor above needed a small baffle to ensure that all the airflow was THRU the condensor and NOT creating a air barrier to escaping hot exhaust air from the condensor. You can see this baffle located in the center section of the horizontal mounting bar. I also added another baffle at the top of the refrig cabinet as the original baffle left a dead air space that trapped hot air above the upper louvers of the access door. I made a baffle that extended from the top edge of the upper door to an area just above the rearmost portion of the condensor and then angled it downward to where it was 1/2" or so above the top of the refrig. This pretty much mirrored what A/S installed, but mine eliminated the dead air issue. I left the original top baffle in place. You can see this baffle in a follow on email as I already have the max 5 attachments on this post.
BTW, the curvature seen in the pics is a artifact of my wide angle lens
After removing all the original fan hardware, I installed the new assembly as shown in the attached pic.
david
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