Hein & Kim's 94 Excella

[Hein]

making progress on the roof....

First photo. Skylight resealed with Flexseal liquid and ready for cover to be added which I plan to attach to the flange with this tape. Interior trim is very fragile due to UV exposure so may replace that. Found one here.



Next photo. I removed the rear Fantastic Fan vent which was old and tired. It had been installed with pop rivets. I ground off the adhesive and rivet heads with a flapper pad on an angle grinder. Once those were gone, I was able to use a putty knife to peel off the old sealant around the flange and then pop the vent loose. Then I ground the rivet bodies flush and cleaned off the old flange sealant. Removal was not as bad as I thought it would be and definitely due for a re-do. Looks like I have some more adhesive to remove...



Plan is to frame out the hole with some expanded PVC strips before installing the new vent. We will CNC those pieces and I'll glue them in with window weld adhesive. The aluminum roof needs better support around the vent hole.

Other hole is for the AC. Latest plan is to install a new Dometic Penguin high capacity unit with drain cups plumbed into the original drain line. I peeled up the smiley face caulk with putty knife and 3M adhesive remover.



Next photo is of the fridge vent with large hole for the solar panel wiring and smaller hole for some other accessory that is no longer present. I'll run a new cable to a roof junction box for solar panels and then seal up this area as well.



More progress coming up.
All the best,
Hein

[dbj216]

You are doing great work on those roof penetrations for vents, skylights, and air conditioners. Getting down to base aluminum is the way to go.

David

[Hein]

Thank you for the encouragement, David. Glad to hear I am on the right track.

The 19x19 front skylight dome is back in place. Photo below shows the seal ready. I ended up using this butyl tape to attach the dome. Before installing it I gently placed some strips of insulation along the sides to fill in the airspace. A few more pieces broke off the interior bezel but decided to leave it alone for now. It is removed from the inside so can deal with it later. Would be cool to have some LED up lighting around the perimeter in there...



Next photo shows Ventline cover with new weather strip and ready to be reinstalled. I put a dab of sealant on each of the metal ears that support the dome and then gently reinstalled the screws.



More work needs to be done on the hole in the rear before the new Maxxair Deluxe vent can be installed. The edges of the hole are pretty ragged with no support from below. The Airstream frame runs fairly close to the rear edge. I found that profile to be flat in the center for 12" and then curve downward 3/8" were the fore/aft frame rails run. So I used that geometry to CNC two bulkhead strips that I will glue in along the front and rear of the opening to bridge the gap between inner and outer skins. Then two more strips along the side to accomplish the same. Photos below shows one of the bulkhead strips while I test the fit. Plan is to bond them in with Windoweld urethane adhesive. I also plan to CNC an adapter for the top that will absorb the curvature of the roof and provide a flat surface for the vent flange. More photos and messy gluing coming up.






All the best,
Hein

[Hein]

I have started gluing in the framing strips and an adapter for the new rear vent. The strips are to frame out the hole between inner and outer skins. The adapter frame is CNC machined to conform to (and preserve) the curvature of the roof and provide a flat rectangular surface for the vent flange on top.





I have also removed the white plastic AS style vent cover located towards the front of the trailer and found another layer of roughly cut plastic presumably for added insulation/condensation control. I am CNC'ing a new inner panel that fits a little better and will also be used to attach the vent cover. Here's a photo of the parts as removed.



Thanks for following along. More progress coming up.
All the best,
Hein

[Hein]

Yea! One vent is back to being weather tight.



Below is a photo of the 6mm thick plastic insulation plate that I made on the CNC. It is positioned upside-down while I install the weather strip seal. The brass things are headed/knurled threaded inserts pressed in from this side of the plate.

Assembled, the metal tabs that lift the cover upward come up through the slots and end up between the cover and the plate. Six #8-32 screws go through the cap, then the metal lift tabs and into the plate with inserts. Holds it all together.

I had to slightly unbend and re-bend the metal lift tabs to get them through the slots. I also added sheet metal screws at the four corners of the cover to secure it to the plate as well. It feels much sturdier than the way it was.

[Hein]

A few more photos from today's accomplishments. Finished gluing in the framing strips and vent adapter. Should be ready to install and seal up the new vent tomorrow.


Earlier, I pulled out the fiberglass insulation around the vent hole and replaced it with 3M Thinsulate. It's 1.75" thick so fits pretty well in the space.


Below. View of roof cavity around vent showing insulation installed prior to the gluing in the framing strips. Headliner is falling down on the inside so will have to deal with that.


Also stuck down a solar junction box with VB tape and ran a 10 gauge duplex wire down to behind the fridge. Not going to install panels now but will be ready when I have time. Just need to focus on buttoning up the roof so the trailer can go back outside.


Last hole to cover is the AC and have pretty much decided to install a Dometic Penguin so hope to get those components ordered tomorrow. Will need the AC itself, Air Distribution Box, Condensate drain kit, and will probably go for a heat strip.

All the best,
Hein

[cballard]

Looks great! Good work!

[Hein]

Thanks for the encouraging words. -And without further adieu, the Maxxfan Deluxe is installed!





As can be seen from the side view, my CNC'd vent adapter preserves the roof curvature and prevents the problem shown in the photo below. The installation of the old vent created a flat low spot in front of 14x14 hole. This is caused by forcing the roof metal flat with the vent flange. Water will pool right up against the seal instead of running off the roof. Not an ideal situation.



Should be good now so on to the AC install...
All the best,
Hein

[cballard]

So low profile, too! Is that lower than a normal unit?

[dbj216]

It is great the way you maintained the curvature of the roof and installed the "flat" MaxAir fan. Maybe you could make these CNC'd curved supports for 14" roof penetrations and sell them for $100 a set or something.

You mention the CNC mill you might have in your shop. Can you describe it. I spent my entire career in machining and remember the first NC tape machines and then the fancy computer numerical controlled machines. They were a great productivity improver. Programming an arc tool path isn't the easiest.

David

[Hein]

Originally Posted by cballard

So low profile, too! Is that lower than a normal unit?

It is a nice looking low profile vent but be aware that it is closed in the photo. This model doesn't need a cowl to keep rain from getting in when open. I'll post a photo of it open but still need to connect the wiring, install the interior bezel and mount the remote holder on the wall somewhere. Oh, and fix the falling headliner.

Originally Posted by dbj216

It is great the way you maintained the curvature of the roof and installed the "flat" MaxAir fan. Maybe you could make these CNC'd curved supports for 14" roof penetrations and sell them for $100 a set or something.David

Thank you for the compliment and business suggestion. We in fact already produce these adapters for a variety of vans. And will produce them for the Airstream trailers as well.

We've made enough already that I have a pretty good stack of 13.5" x 13.5" 3/4" thick squares (result of cutting the 14x14 hole) that have come in handy around the Airstream as parking pads and jack pads. They are waterproof and plenty sturdy on mostly flat surfaces. We are using them to help level the trailer before lowering the jacks. Just seems better to have most of the load on the axles and only use the jacks to stabilize.

Originally Posted by dbj216

You mention the CNC mill you might have in your shop. Can you describe it. I spent my entire career in machining and remember the first NC tape machines and then the fancy computer numerical controlled machines. They were a great productivity improver. Programming an arc tool path isn't the easiest. David

We just upgraded to a new machine last year. We use Pro/Engineer, Creo, and Solidworks parametric CAD software for 3D design and programming. We've come a long way from the early days of CNC. Our new machine:



Got the trailer back outside and have been remounting the rock guard hinges so can get the rock guards back on. They needed a little TLC and I waxed the tinted plastic.



Funky thing was that the hinges were screwed through the window frame on the right side of the trailer and through the body on the left. The latter had holes stripped out so decided to remount those with screws through the window frame as well. I backed the hinges with VHB tape and built up an extra layer to fill in the height difference between the window frame and the trailer body. Photos tell the story.

Right side hinges mounted to window frame. Just remounted these with VHB tape and new screws.


Left side hinges were through body and holes were stripped.


Remounted those to window frame with VHB and screws same as the RH side.


Ready for screws.

Forgot to take a photo with the screws installed.

All for now. Dometic Penguin air conditioner came in so ready to start that install and will be machining a few parts to make that fit nicely.

All the best,
Hein

[Hein]

I cut a larger adapter plate for the Penguin air conditioner. Not 100% sure this is a good idea but will probably just go with it.

The benefit, I believe, is in getting the AC seal above the roof and away from possible standing or flowing water. I will seal the perimeter of the plate to the roof and it will be accessible for maintenance. The adapter plate also absorbs the curvature of the roof and better supports and distributes the weight of the AC. So it stays sitting level.

Need to decide on the best strategy for bonding it to the roof. Should I go permanent with an adhesive or use butyl tape to make it removable should that need arise? I could run some screws through the plate into the aluminum skin and/or structure. I thought of vacuum bagging it to the skin in some way but probably not practical. Definitely willing to consider other ideas and opinions. Rain is coming so need to get this done.



All the best,
Hein

[Hein]

Here (photo below) is what I ended up with. A smaller front adapter around the 14x14 hole and a spacer/load strip for the support blocks on the on the rear corners of the air conditioner pan (see last photo). The adapter and load strip span out across the trailer frame structure so the AC's weight is carried by that instead of bearing only on the floppy skin. Also keeps the AC level because the elevation of the adapter and spacer is the same.



multiple beads of Windoweld adhesive.


photo below. Underside of Dometic Penguin showing seal and location of support blocks. I actually moved the front blocks to more logical locations based on the application.


Hope to get the air conditioner on the roof in the next day or so.
All the best,
Hein

[blkmagikca]

What are you doing to drain the condensate? There should be some kind of tray that attaches to the tube that drains the condensate at the front of the road side wheel (at least that what I have on my 1987 Excella).

[Hein]

Originally Posted by blkmagikca

What are you doing to drain the condensate? There should be some kind of tray that attaches to the tube that drains the condensate at the front of the road side wheel (at least that what I have on my 1987 Excella).

I ordered the 3107688.016 condensate drain kit from Dometic. Started to install it but the fit of the drain hose where it goes through each side of the seal gasket is not great so need to redo that a bit. I could actually make the drain pans part of the adapter so that might be a solution.

The previous AC unit (not original) was draining onto the roof but I saw the internal drain line when I removed it. I appears clear.

All the best,
Hein

[Hein]

Nice weather is continuing so finished up prepping the adapter and spacer/load strip for the AC. I'll post some photos of the drain pad mod & install later.

First photo. Adapter and spacer/load strip bonded to roof with 3M windoweld adhesive. Shortly after this photo I added an aluminum strip to cover the top of the shim to make it more rigid. Sort of a sandwich composite made up of the AS roof metal, the CNC'd expanded PVC spacer (core) and then the top skin of aluminum attached with a VHB tape. I think it will support the rear of the new AC nicely. It feels sturdy especially out by the ends where the AC support blocks will rest.


Another photo (below) after I coated the top, sides and onto roof with Flexseal liquid. I didn't coat where the seal gasket will end up because I plan to bond that to the roof with a layer VHB tape as well.
Still to do: Install heat strip in AC; Rework drain pans & install and plumb those on the AC. Then place AC on roof, install interior frame and 4 clamp bolts, connect wiring and install ADB.
All the best,
Hein

[Hein]

Worked on the drain cups today. The kit comes with an additional seal gasket which is added to the existing one after running the drain tube through. This is needed because of the position of drain tube port on the cups. The additional seal and spacer blocks raise the AC over 1". I didn't want to do that for cosmetics and a concern that the AC could sort of teeter on the added foam as the trailer was moving.

I cut down the cups (essentially removing the flanges) and also cut off the hose nipples. Then drilled out the port so I could press fit in a 3/8" ID poly hose. No nipple. This is a gravity, no pressure drain line so should seal fine. I also added some notches along the ridge of the cups to allow for overflow should the primary drain become clogged.

First photo is of cut down drain cup with VHB tape on edge to mount it to the bottom of the AC pan. Didn't think to take a photo of it before I removed the flange and nipple. I started cutting with a band saw and this is what was left. Soap dish.



Photo below. Drain cups and plumbing installed on air conditioner. The tubing is centered vertically on the existing seal so another seal foam layer is not needed. The poly tubing is more rigid so less likely to collapse (when the seal is compressed) than the vinyl tubing supplied with the kit. Holes in seal were bored with a step drill with 1/2" max diameter. I'll inject a little sealant around the tubes before installing the AC on the roof. I want that to cure with the seal compressed. To hold the cups mechanically, I drilled holes in the bottom and screwed them into the AC pan. The kit also uses self drilling screws (through the flanges) to mount the cups. I sealed the heads against the cups. They are #8x1.25 stainless screws.


Heat strip is installed so pretty much ready to heave the Penguin up on the roof, clamp it down, connect the drain tube and 120V wires.
All the best,
Hein

[Hein]

Overlooked a detail. Even with the cups cut down. They were going to rest on the roof when the seal was compressed. So needed to shim the seal and support pads after all. But only by 3/8" on the seal and 1/4" on the pads. Also took time to spray the cups with some black bed-liner spray to match the bottom half of the AC. The existing seal foam is 2# density minicell so used some 3/8" sheet to make a one piece gasket. Used a slightly harder EVA foam for the pad spacers. Glued on with 3M 90 spray spread out with a foam brush.



We lifted the AC up on the roof upside down and onto a moving blanket draped over the awning side. Then flipped it over and moved it into place. Pretty easy.

So onto the inside to install the ADB. First problem was the Airstream internal drain tube comes out where the 120V connection box is located. So needed to move that over. More on that plumbing later. In the process discovered that spaces next to air conditioner structure are uninsulated. So poked some 3M Thinsulate through some existing holes and distributed it in the space.

UN-insulated space. That's the condensate drain tube.


Poking in strips of Thinsulate SM600L (white fluffy stuff to right of photo)


So the AC is sitting in place on the roof but still need to clamp it down, connect the condensate drain, connect the power and install the ADB. Rain is forecast so good to have all the roof work done.

All the best,
Hein

[dbj216]

I find myself making "adjustments" all the time. Our projects don't exactly have a set of drawings and developmental prototypes like Airstream might have.

Very nice adjustment to the drain cups, and to the uninsulated area noted.

You will be ready for some rain.

David

[Hein]

Thank you for the reply, The the rain and even some small hail (no damage) has arrived.

Indeed there was another adjustment needed on the forward OEM Airstream vent where I added the CNC'd plate for insulation. The new seal I used at the time was too short so there was a unsealed gap towards the front. I have since installed a thicker foam seal. Found I could more easily remove the cap by removing the screen and then 4 screws on the slider blocks that allow the vent to open vertically. Below are some photos of the work done.

First photo. Vent cap off and supplies ready. Also shows the inserts in the plate that are used to hold the cap and metal lift tabs. (see earlier post)


Below, Lightly sanded the perimeter and brushed on some 3M 90 spray to prime the plate so the weather strip would stick better.


Below. Cap all done and ready to re-install on the trailer.


Finally done crawling around on the roof and somehow managed to get the air conditioner installed on the last possible day before the rain started. I didn't get it clamped down right away but it still was sitting level enough to keep water out. Some photos:


Side view below. Maybe the unit will run a little more efficiently (cooler) because our adapter and spacer allow for better airflow underneath.


Interior view below. New ADB (air distribution box) inside almost covered everywhere the old unit did. Using the adapter plate on the roof, I was able to position the AC a little forward of the old location so the new ADB would cover more of the ceiling upholstery. The push pins are a solution to drooping headliner in this vintage of AS. At first we thought they were OEM. They look vintage (and laborious to install) but I may need to do more of those in a few spots. Can anybody point me to where to get more of these?


A Couple more photos taken before installing ADB.

Below. Stuffing strips of insulation past the 120V wiring with one of the AC clamp bolts. Multiple (15 -20) strips are inserted and then distributed in the space.


More insulation stuffing and photo shows how drain plumbing was routed.


Below is one more photo of the Maxxair vent in open position. This model doesn't need a rain cap.


Next up...
One of the stove controls was jammed and not turning off completely so need to replace a valve.

All the best,
Hein