Removing rooftop A/C unit - covering the hole?

[K8MEJ]

My next project is installing a Pioneer 12K BTU, 120volt mini-split in my 2018 Grand Design Imagine 2800BH. I am going to remove the rooftop A/C unit so that I can install additional solar panels. But this isn't a question about solar, batteries, wiring, mounting, etc.

I have a white TPO roof. Do I simply frame in the opening, cover with plywood, and then glue down some TPO and then use Eternabond tape around the edges to seal it against the original roof? My roof is crowned, so trying to match the curve and flex the plywood with only a 14" piece is not going to be easy. Maybe I should use a couple of layers of luan plywood instead and flex each one individually?

I have no ideas for what to do with the opening inside the trailer. I don't want to put a vent in the hole because I already have plenty. I'm not worried about how the roof looks, but I do care how it looks inside.

My question for those who have removed their rooftop A/C is what did you do to cover over the 14" x 14" hole left behind?

Thanks in advance.

 

[Boondock Saint]

I removed both skylights. The RV place used plywood which was larger, then screwed into the box that was left. They used some roofing fabric and eternabond. I hate it.

If I were you, I would cut a piece of plywood to the 14" x "14 (measure twice cut once) and use bracketing all around on the underside of the board to the frame making a reasonably flush surface. You're lucky because the AC actually HAS a box to join to whereas my skylights did not.

On the top use some flashing glued down, and cover with roofing material and eternabond. You can prob get free scraps from a local RV place.

On the underside, I would fill with mainly styrofoam board and the expanding foam insulation to fill the cracks and hold into place.

If you secure the wires that were going to the AC you could reuse them to provide additional lighting or a ceiling fan etc.

Good luck on your project!

 

[K8MEJ]

I just thought of another idea. There is a company that makes Lexan skylight covers. I could get a trim kit for a Maxxair fan for the inside or maybe purchase a trim kit for a 14x14 skylight for the inside and then use the company I found to make a 2" high dome for the outside. I think I have enough clearance with my Unistrut _ Ecoworthy tilt mounts to install a panel over the skylight. I'll measure to make sure, but this might be the easy solution. And if I use colorless Lexan, it'll give me a little ambient light during the day even with the panel over top.

 

[RogerD]

You can heat weld the seams of TPO.

While those that do it professionally use expensive heat guns. Pretty sure a cheap one with the proper fitting will work fine.

 

[Zwy]

You can heat weld the seams of TPO.

While those that do it professionally use expensive heat guns. Pretty sure a cheap one with the proper fitting will work fine.

I didn't know it could be done, thanks.

 

[RogerD]

I didn't know it could be done, thanks.

It's pretty cool. I learned about it from watching videos by RV Roof Install YT channel.

https://www.youtube.com/c/RVROOFINSTALL/videos

 

[HRTKD]

How about putting a remote controlled .50 cal turret in place of the A/C?

As you suggested, making a curve with Luan to match the roof profile would be the way to go. Trying to match interior patterns is difficult. Maybe put in an audio speaker?

 

[Son_of_Scotland]

If you haven't done this yet, there is such a thing as bending ply. Comes two ways one, bends along the lenth and the other the width of a sheet of plywood. I have some and could send you a piece.

 

[eXodus]

Put in a low Profile Side vent Fan. Like the Dometic EZ-Breeze.

I'm currently installing one to go over it with the panels- needs only about 4.5 inches of clearances - the panel itself provides 1.5 inches + 3 inches from the mounting hardware.

I think they are discontinued - but you might find one somewhere local. I picked up two at campingworld. The design is like made for underneath panels. Flat top and not moving parts outside.

 

[featherlite]

The RV maintenance man I follow on youtube hates Eterna Bond tape because the outer film is not UV resistant. Consequently, when subsequent maintenance is required (which is inevitable) the tape must be removed, which removal is relatively time consuming. Nothing can be applied over the top of the rotted tape.

His preferred method is to use self leveling Dicor. When the Dicor seal eventually needs maintenance, simply clean the affected area with a rag and cleaning solution, then apply new Dicor over the old Dicor.

 

[Zwy]

A friend of mine always says the "good stuff" either stinks like hell and/or is hard to get off.

I believe that is true. Dicor now makes a tape just like the single sided Eternabond. Imitation is the simplest form of flattery. If you want to protect the outer fabric, simply paint it. It is UV light that breaks that fabric down over time.

As for Eternabond double sided tape, without the fabric on the one side, it is used by RV manufacturers at the factory instead of butyl. It works very well in this application. I used the double sided on my TC solar mounting, it works perfect but is a pain to get off your hands.

 

[HRTKD]

Eternabond is a heck of a lot easier/quicker to install in the field than Dicor Lap Sealant.

 

[12VoltInstalls]

Henry Solar White Elastomeric Roof Costing over everything is what I’d do.

 

[richard cabesa]

I just thought of another idea. There is a company that makes Lexan skylight covers. I could get a trim kit for a Maxxair fan for the inside or maybe purchase a trim kit for a 14x14 skylight for the inside and then use the company I found to make a 2" high dome for the outside. I think I have enough clearance with my Unistrut _ Ecoworthy tilt mounts to install a panel over the skylight. I'll measure to make sure, but this might be the easy solution. And if I use colorless Lexan, it'll give me a little ambient light during the day even with the panel over top.

I would definitely turn it into a skylight or a vent.. You can never have enough air movement when it gets hot.
Covering a skylight with a solar panel was actually a plus in my rig. The skylight over my shower absolutely made the entire RV miserable from the solar gain in the small bath with the minimal window ventilation. I put a panel over the top of it and now I have nice soft natural light without the heat gain. You are not in there to look at the stars.

I am going to do a split AC soon so I'll have that hole to cover as well. I had not seen the Dometic side vent mentioned in this thread but I think that will be my answer to that hole. That and another to replace my existing giant Fantastic fan and I could gain 200 watts of solar to help power the split unit.

Thanks eXodus for that fan suggestion

 

[corn18]

I would definitely turn it into a skylight or a vent.. You can never have enough air movement when it gets hot.
Covering a skylight with a solar panel was actually a plus in my rig. The skylight over my shower absolutely made the entire RV miserable from the solar gain in the small bath with the minimal window ventilation. I put a panel over the top of it and now I have nice soft natural light without the heat gain. You are not in there to look at the stars.

I am going to do a split AC soon so I'll have that hole to cover as well. I had not seen the Dometic side vent mentioned in this thread but I think that will be my answer to that hole. That and another to replace my existing giant Fantastic fan and I could gain 200 watts of solar to help power the split unit.

Thanks eXodus for that fan suggestion

Hmmm, never thought to mount my panel over the shower skylight. I did paint it with white plastidip and that helped a lot. But I was looking at my panels and I could just slide the one panel that is forward of the skylight aft on the unistrut and cover the skylight. Might add that to the todo list.

 

[backwoods]

The RV maintenance man I follow on youtube hates Eterna Bond tape because the outer film is not UV resistant. Consequently, when subsequent maintenance is required (which is inevitable) the tape must be removed, which removal is relatively time consuming. Nothing can be applied over the top of the rotted tape.

His preferred method is to use self leveling Dicor. When the Dicor seal eventually needs maintenance, simply clean the affected area with a rag and cleaning solution, then apply new Dicor over the old Dicor.

I hope this isn't the same guy who used silicone to fix a slideout, because they hate eternabond tape.
I hate silicone.


EternaBond® also offers high-grade UV-light protection and is engineered to flexibly bond to the surface to prevent shrinking and cracking in roofs and seams, which are exposed to repeated environmental stress.

 

[12VoltInstalls]

I hate silicone.

As well you should.

Silicone is like a crunchy taco: a practical joke nobody figured out. Let’s put something soft and runny in a hard crumbly thing and try get people to eat it.
Silicone caulking has one application: holding glass or glass frames to metal, stone, or plastic (think fiberglass boat). Lexel is a much better choice than silicone but often isn’t as good as other products in many applications. It’s acidic, doesn’t stick to wet, and isn’t very long-adhering.

 

[richard cabesa]

Put in a low Profile Side vent Fan. Like the Dometic EZ-Breeze.

I'm currently installing one to go over it with the panels- needs only about 4.5 inches of clearances - the panel itself provides 1.5 inches + 3 inches from the mounting hardware.

I think they are discontinued - but you might find one somewhere local. I picked up two at campingworld. The design is like made for underneath panels. Flat top and not moving parts outside.

So it seems this powered vent is discontinued from Dometic. Be careful if you look these up on eBay and Amazon. Many of them describe them as a fan, and show it, but they also say non powered.

camping world has the side opening exterior portion for $27. I can’t imagine that it would not be comparable with their interior 14x14 fan units. I’m throwing $55 at it to find out.

im taking off tomorrow for over a month. Will let you all know after I return

 

[eXodus]

here what I did because of the Vent- was able to mount 2x 435 panels.

 

[eXodus]

The vent is underneath the rear of the two panels. The front one slightly angled up. So creating a flat tent. Or "solar hump"

Solar "Hump" for aerodynamics for Class A RV

I'm currently fitting large 435W on my RV. (82x 40 inches) My idea is to fit the long edge (82 inches) across the roof and create a kind of spoiler hump in the front of the RV. (Primary use - is to clear above the vent) This is recently done in Bus design and I saw it on some newer Class C...

diysolarforum.com

The whole contraption is not more then 5 inches tall in the middle and about 6 inches at the side (curved RV roof)