Aluminum Fridge Vent

The fridge vent shroud has been an unexpected 3-day delay. But once it’s installed I will be a lot happier with it than with the plastic. I’ve always been rather nervous about making a microwave shelf above the fridge, since the plastic vent was exposed and could be damaged.

When I took the partitions away from both sides of the fridge, I could see the the plastic shroud was not only cracked and leaking CO into the living space, but it as aligned not quite right and was taller than necessary.

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I decided to replace it with aluminum. The first task was to bend some channel to fit the shell curve (I wanted a tight seal against the shell). Each one was done separately. The result was very different; as much as 3/4″ difference along the curve. What this meant was that the shape of the inner skin of the new shroud would determine the construction, not the shape against the shell, since that varied so much. Sort of like building from the inside out, rather than the outisde in.

The end pieces were easy to cut–their outer edge matched the formed channel and the inside was measured from the top of the fridge and then the shape was just geometric, per the dotted lines you can see on the end of the plastic shroud in the comparison photo. Bending the inner skin was a
challenge–the plastic mallet leaves small indentations along the crease, but not terrible. Getting the curve right without using a radiused form was just plain luck.

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The final design objective was to reduce the total space used by the shroud and perhaps get an additional shelf above the microwave. Stand by to see if I was successful…

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By the way, all the joints are sealed with Vulkem to ensure no fridge combustion gas is vented into the interior of the trailer.

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I need am outlet for the microwave shelf (above the fridge) and space there is tight, so I will put it in the chimney shroud. Sheet metal isn’t all that stiff, so the recepticle box needs to be braced to prevent oil canning or permanently bending the surface if the plug is hard to insert/remove.

Since the chimney needs to be air tight, the flanges of the brackets also provide surface for the Vulkem to seal the box into the skin. One of the brackets was bent so that it would pick up the existing rivet pattern along the edge.

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I looked for a wall plate to match the skin, but the steel plates are too small and the decorator plates are either the wrong color or coated with thick lacquer, which looks bad up next to the bare aluminum. So I thought I’d try my hand at making one. It took about an hour. All that was required was a hard wood block with two edges shaped to form the edges of the plate, a couple clamps, and
a mallet. To prevent multiple little ding marks on the edges, a long piece of 3/4″ wood should be used against the slightly exposed edge of the plate. The mallet can be used directly on the corners to “shrink” them a little and form the rounded connection between the adjacent edges.

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Not perfect, but I like it better than what is commercially available.

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Jus a quick look at the beginnings of the fridge and pantry installation. More shelves will be appearing on the aft side of the fridge.

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Two significant new things, here. First, the vent is insulated. This turned out to be non-trivial, since any failure of the glue (spray-on contact cement) would result in a huge repair project. So I added some mechanical insurance. The insulation is 3/4″ foil-faced foam.

Second, I plan on installing a three-fan panel at the bottom of the chimney, powered by a small solar cell. These fans are very low power. The small switch is a SPDT/center off model that will allow me to switch between off, one fan, and three fans. I don’t think this many fans are required, but in order to provide plenty of open cross section for air flow when the fans aren’t operating, two fan diameters didn’t seem like enough.

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