lostcoast Posted August 13, 2009 Share Posted August 13, 2009 We just bought a Nova Star that leaks at the rooftop ac installation. I thought I read somewhere that you could use vicor (vycor?) to reseal them in place of a rubber gasket....is this possible? Any other tips or tricks to resealing these? Also does anyone know what the construction of the roof for these rigs are? Im guessing plywood laminated to the glass but the roof is sagging at the ac (which is probably contributing to the issue) and Im hoping that I dont have a rot problem. The roof 'knocks' solid. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
Bodybagger Posted August 13, 2009 Share Posted August 13, 2009 I removed my AC and screwed down a curb made from a 1" thick, 14x14 inside by 18x18 outside piece of high density foam roof insulation. I applied Peal & Seal over it with a heat gun and rubber lap roller. THis was applied over a new Peal and Seal roof, and buffered 3inches to allow for sealing. I used 2 layers of camper shell weatherstripping as a gasket between the curb and the AC, and reinstalled the AC. Hasn't leaked a drop since. Quote Link to comment Share on other sites More sharing options...
gmichaelz Posted August 13, 2009 Share Posted August 13, 2009 We just bought a Nova Star that leaks at the rooftop ac installation. Any other tips or tricks to resealing these? It could be as simple as removing the inside garnish trim ceiling panel and tightening the three hold down bolts with a suitable socket, possibly 9/16 inch. These mounting bolts loosen due to compression of the rubber seal between the roof and the bottom of the AC unit, also vibration will loosen them more. Usually, but not always, the roof develops a sag from the weight of the roof top AC unit, so any moisture from rain, dew, washing, and of course the operation of the AC unit places condensate from humidity removed which will pool in this low spot / sump area and will find an entrance point into your ToyHome if these mounting bolts are even slightly loose. Quote Link to comment Share on other sites More sharing options...
Tom W Posted August 13, 2009 Share Posted August 13, 2009 Those bolts mentioned that hold down the AC on mine there screwed down all the way springs fully compressed doesn't look right to me but it doesn't leak even with the roof sag. Interested in Bodybaggers way of doing it and where the foam came from etc and probably can't use the original gasket?? Quote Link to comment Share on other sites More sharing options...
lostcoast Posted August 14, 2009 Author Share Posted August 14, 2009 (edited) Thanks guys, I took another look at my setup and found 1) two of the bolts that hold the ac down were loose, so I tightened them and 2) my unit is installed in a similar method to Bodybagger's except with plywood and some black tar looking sealant. Im hoping that tightening it down will work well enough for the rest of this summer (what little we have left) and then Ill rip the existing installation out and try the Bodybagger method. As Tom mentioned, Im interested in knowing more about the high density foam...what color is it? Blue? I know there are a handful of different kinds out there but Id rather not buy a sheet for something that I can find a scrap of. Also, how did you manage the corners? Since my roof is fiberglass, what do you guys think of glassing a dam in on top? Edited August 14, 2009 by lostcoast Quote Link to comment Share on other sites More sharing options...
turtle Posted August 14, 2009 Share Posted August 14, 2009 Since my roof is fiberglass, what do you guys think of glassing a dam in on top? I built up a riser out of wood which was covered with fiberglass when I cover the entire roof in fiberglass. This was for a power vent not AC unit but the idea is the same. Quote Link to comment Share on other sites More sharing options...
Bodybagger Posted August 15, 2009 Share Posted August 15, 2009 Anything will work. I used a high density foam insulation panel for flat rubber roofs because we install rubber roofs and I had a ton of that laying around. I cut an 18" square shape from a single sheet of insulation, then cut the 14" square shape out of the middle - it's one piece to maximize rigidity. The foam is just a spacer. The membrane you apply to it is what actually seals the water. So plywood would work. But I think a high density foam would work best because when the AC is screwed down, it will conform to bottom better. Maybe when I get enough free time on my hands to take the AC unit out of its hole, I can take some pictures of how I made the curb. But yeah, a 1" waterproof curb and you go from completely relying on a gasket to not really even needing one. Quote Link to comment Share on other sites More sharing options...
Maineah Posted August 15, 2009 Share Posted August 15, 2009 I have a plastic Nova Star also and my A/C was leaking slightly in a driving rain. At the time I was not sure it was the A/C but I had resealed every thing else it did not leak through the A/C but ran down the edge and across the top of the interior roof paneling and came out by the cabinets. Well some where along the line some wing nut had glued the A/C to the roof with silicon all the way around it I had to literally cut the thing from the roof with a special tool. There was a gasket under it maybe the original about 5/16 thick. My roof has a bow in it also but now the rain can run from under the A/C instead of sitting inside. I bought the gasket from an RV dealer it was about 1 1/2 thick and sticky on one side to keep it in place. Once it was compressed it probably sits up off the roof about 3/4 to 1" it comes with 2 pieces that fit on the rear of the A/C to make it level. If yours is fiberglass they put the top fiberglass piece over a plywood roof supported by 3/4" aluminum bows it is not glued. It rained here in Maine 10" in both June and July and it has not leaked a drop and is considerably quieter! The RV dealer told me the gasket should be fine for at least 5 years. Quote Link to comment Share on other sites More sharing options...
lostcoast Posted August 31, 2009 Author Share Posted August 31, 2009 I have a plastic Nova Star also and my A/C was leaking slightly in a driving rain. At the time I was not sure it was the A/C but I had resealed every thing else it did not leak through the A/C but ran down the edge and across the top of the interior roof paneling and came out by the cabinets. Well some where along the line some wing nut had glued the A/C to the roof with silicon all the way around it I had to literally cut the thing from the roof with a special tool. There was a gasket under it maybe the original about 5/16 thick. My roof has a bow in it also but now the rain can run from under the A/C instead of sitting inside. I bought the gasket from an RV dealer it was about 1 1/2 thick and sticky on one side to keep it in place. Once it was compressed it probably sits up off the roof about 3/4 to 1" it comes with 2 pieces that fit on the rear of the A/C to make it level. If yours is fiberglass they put the top fiberglass piece over a plywood roof supported by 3/4" aluminum bows it is not glued. It rained here in Maine 10" in both June and July and it has not leaked a drop and is considerably quieter! The RV dealer told me the gasket should be fine for at least 5 years. Yarp, mine is FRP Id say that the bow near the unit (in the center of the roof) is about 1/2" (maybe a little less but noticeable)....funny that there is a bow in the roof with the aluminum x-members. One of these days Im going to pull that ceiling off and redo 'er. Ill poke around and see if I can find a similar gasket - sounds like it might be a quicker fix (although regardless of what I do, Ill have to un-do the 'work' that the previous owner did.... Got to tackle this before it starts raining here in oregon (soon). Quote Link to comment Share on other sites More sharing options...
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