Fridge Flush-fit Lower Vent Plug Install

February 05, 2020, 12:50:17 am

Here's how I did ours.

The opening:

1) First, you'll want to remove the fridge for inside access.

2) Remove original lower vent cover.

3) Remove the white elastomeric sealant from the opening, including any sealant on the interior wall. The rough opening should be about 28-3/4" W x 14" H.

4) Build a router fence with inside dimensions of 34.75"W x 19.75"W. I used straight 1x4 lumber; Make sure the corners are all 90 Deg. to insure the cut opening will be square, and the screws are not protruding through the back side) Note: Inside dimensions assume a plug, 30"W x 15"H, the size as the original vent cover, a 6" router base, and a first cut using a 1-1/4" router bit. (See pic #1) Also, cut 4 pieces of 1x4 to 24" , each with 2 holes, to span the vertical rough opening and fence, plus 4 lengths of all thread with 8 nuts and flat washers, to be used to clamp the fence to the exterior wall.

5) Make sure the exterior wall and fence are clean, so as to avoid scratching the exterior. Roughly center the fence around the rough opening on the exterior wall and lightly clamp it to the wall with the 4 24" pieces of 1x4 and hardware. Space the 1x4 clamps with the center-most sides about 3-1/4" from the horizontal fence center-line, to allow the router to cut to the center of the fence on the horizontal cuts. Mark the locations of the clamps on the horizontal part of the fence, top and bottom, and put a screw in the top, just far enough in to hold the clamp in position. (Don't screw into the wall of your coach!!!)

6) Precisely center the fence up/down, left right: If there's no graphics on the original vent, center it on the original rough opening. If you have graphics (decals or color change on the original vent cover) center to where the color change stops, assuming the vent cover was installed when the graphics/paint were applied and the color change didn't go under the vent cover. (Doing this should have the first cut, which is the recess for the cover face and gasket, to the edge of the graphics, minimizing any paint or color cut-in of the existing graphics) Make the fence level with the metal beltline above the bay doors, check the fence for square (all corners 90 Deg).

7) Clamp and prep: Tighten one of the 1x4 clamps tight. (About as tight as you can without breaking the wood clamps) Remove the other clamp. Use blue painters tape protect the exterior surface exposed within the fence. Do not overlap the tape. (See Pic #2) Go inside the coach and mask-off the inside of the opening. Be particular with the inside masking, as you are about to make a lot of debris. Note: Interior masking will have to be partially removed/replaced when moving the clamps in step 8. It's also a good idea to vacuum the area before removal of the masking.

8) Cut opening for flush plug: Wear protective gear! Eye and breathing protection as a minimum. (For details, see pic #3)
First cut: Using a 1-1/4" carbide mortise cutter, set to .220" depth of cut, follow the inside of the fence on the side without a clamp. (Half of top, one side, half of bottom. Install and tighten the clamp removed in Step 7. Only after the second clamp has been tightened, loosen and remove the opposite clamp. The fence must not be allowed to move. Finish the first cut on the opposite side. The first cut should be 30"W x 15"H, and is where the plug face and outer seal will fit into..
Second cut: Using a 3/8" carbide cutter, set to .7" depth of cut, follow the inside of the fence on the side without a clamp. Install and tighten the clamp removed prior to finishing the first cut. Only after the second clamp has been tightened, loosen and remove the opposite clamp. Finish the second cut on the opposite side. The second cut should be 29-1/8"W x 14-1/8"H, and is where the plug sub face will fit into. While making the cuts, you might run into a few staples. I did. Take your time, it shouldn't be a problem.

9) Vacuum the area, remove all masking, remove the clamps and fence. Replace interior masking.

10) Corner radii: Use painters tape to mask off the exterior wall around the first cut. Leave a 3/64" reveal of the exterior surface. Using sand paper, gently make a .03" radius on the transition for the first cut to exterior surface. (This eliminates the sharp edge, reduces the chance of chipping, and just looks a whole lot better)
Using sand paper, gently make a .06" radius on the transition for the first cut to the second cut. This transition is on the outer layer of rigid foam and it won't take much to get the radius. (See pic #4) Vacuum the area and remove interior masking.

11) Install interior seal flange: Cut 1/8" x 1-1/2" 6061 aluminum bar into 2 pieces 13" long, and 2 pieces 30-3/4" long. Drill 7/32" mounting holes, 3/8" from outer edge, and attach to interior wall, centered around the rough opening, with #10 x 1" screws. This will leave about a 1/2" reveal, as seen from the outside, to attach the inner seal. (See pic #5)

12) Seal the raw opening: Mask off the interior by taping to the aluminum flange installed in step 11. Mask off only the edge of the exterior FRP body sheet exposed in step 8, "first cut. Brush paint all exposed wood and foam with 2 thin coats of elastomeric roof coating. (See pic #6) It will be easier to remove the masking tape immediately after each coat, and re apply tape for the second coat. When the elastomeric is dry, apply a 1/8" or smaller bead of urethane sealant to the aluminum flange/rough opening interface, leaving 3/8" of aluminum exposed for placement of the interior seal.

13) Paint the exposed raw edge of the exterior FRP: Consult your painter for this step. Our coach has "po-boy" full body paint... Except for the nose cap, below the windshield, the graphics were painted directly to the gelcoat, and then the whole coach was shot with clear. I treated our rough opening the same as I would for full body color coat. That is to say, there was a line around the vent opening where the original vent masked off the body from the clear coat. I centered the fence off of than line, and the first cut came right to it. I carefully masked off the clear coat to only reveal the raw edge of the FRP, and then gave it a few coats of white. After removing the mask, I wet sanded the masking line with #1000 and, after a light polish, it looks pretty darn good.

Continued in the next post.
Greg

Re: Fridge Flush-fit Lower Vent Plug Install

Reply #1 – February 05, 2020, 12:51:30 am

The Plug:

14) Make the sub-face: Cut a piece of flat, sanded, 1/2" plywood to a minimum of 29-1/16"W x 14-1/16"W. Round the 4 corners to a 1/4" radius. Fit the sub-face into the opening made in Step 8, Second Cut. If needed, sand the edges to achieve .020"-.030" clearance on all four sides. (Total vertical/horizontal clearance of .040"-.060") The fit of the sub-face in the second cut will be used to laterally locate the plug in the opening. Remove the sub-face and rout/sand a .06" radius on the edge face that will be facing in.

15) Make the spacer: Using top quality dimensional lumber, cut 2 pieces of 3/4"x 1-1/2" to 28-3/8". Cut 2 pieces of 2"x 2" to 12-1/8". Rip, and/or, plane all four pieces to 1.125". Assemble the pieces, using glue and screws, to make a rectangle with outside dimensions of 28-3/8"W x 13-5/8"H x 1.125" Thick. Round the 4 outside corners to about 1/8" radius. Rout/sand a 1/16" radius on the 4 sides facing the interior. This should give about 3/16" clearance on all 4 sides in the original rough opening. (This clearance is not critical, so long as it's more than the clearance achieved in Step 14.

16) Attach sub-face and spacer: If the fence was centered on the original rough opening, in Step 6, center the outer side of the spacer on the inner side of the sub-face. If the fence was centered on the graphics, place the spacer, and then the sub-face, into the opening. Center the spacer in the opening and determine where it should be, relative to the sub-face. Mark the position. Using glue, and screws, attach the outside of the spacer to the inside of the sub-face, Screws should be driven from the outside of the sub-face, and counter sunk flush or slightly below, the outer surface of the sub-face. Do not place any screws near the center of the ends, since they'll interfere with with the holes for the latching system.

17) Cut Inner and Outer Face: Using .060" FRP, (I used ".090 FRP" from Lowes, that is actually around .075", and sanded the textured side to achieve .060" thickness) cut 1 piece to 30"W x 15"H for the outer face, and 1 piece to 28-1/4"W x 13-1/2" for the inner face. Round the corners and break all the edges on the inner piece.

18) Bond the outer face to the sub-face: Center the outside of the sub-face on the outer face. Mark, or put stops, on the outer face to repeat the alignment. Apply a bonding agent to the outer sub-face and bring the outer face to it, properly aligned. Clamp the assembly. (I used 3M 760 UV for the bond, and spread it out with a putty knife. This was a PITA, so consider something else). When the bond is cured, run a 1/8" bead of paint-able urethane sealant around the interface.

19) Fit the outer face to the opening created in Step 8, First Cut: Place the plug into the opening, center it left/right, and allow gravity to locate the up/down position. Note the amount of material to be removed from the edges oversized FRP outer face that will allow it to fit inside the first cut opening. Remove that material by sanding. Check the fit again and sand more material to achieve a uniform 3/64"- 1/16" clearance on all 4 sides. One you're satisfied with the clearance, sand a 1/32" radius on all of the inside and outside edges of the FRP outer face.

20) Insulate, and attach the inner face: Cut a piece of 1" rigid foam board to fit snugly into the cavity created by the spacer and push it in. Apply urethane sealant to the inside facing side of the spacer, center the FRP inside face on the spacer and clamp. Remove any squeeze-out. (See Pic #3)

21) Prep plug for, and fit locks: The way I did this will be impractical for most, but I'll give a suggestion for an alternate. A cam lock similar to this, McMaster-Carr that mounts in a 3/4" through hole would probably work, provided the mounting holes were counter bored, from the inside, to a depth that allows securing the mounting nut.

22) Prep and Paint: Consult your painter for this step. I would paint the entire plug the base body color, install the inner seal, locks, install the plug, mask the lock faces, and paint the graphics on the plug before installing the outer seal. Your painter may have a better method.

23) Install seals: The seal material I used is McMaster #93085k66. (See Pic #4) You'll need about 18'. Install to the inner seal flange and the face of the first cut. (See Pic #5)

Finished plug, sans paint (See Pic #6)

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