First warranty experience with Northern Lite

insp1505 wrote:
Skipro3- If the thermometer got that hot from the direct sun then didn't the plexiglass get just as hot in the same direct sun regardless of air temp?

No. Not any more than glass gets hot shining the sun into your house onto a solid colored object. If the sun shines through a window into your house, the glass doesn't get any hotter than the outdoor air temperature, but the object the sun finally reflects off of does get hot as it absorbs the radiant energy of the sun.

insp1505 wrote:
I do understand objects become hotter in direct sunlight.

Not all objects. Just objects that absorb the sun's energy. Did you actually measure the temperature of the plastic skylight cover? The only thing known is the temperature of the thermometer in direct sunlight as it absorbed the sun. An infrared sensor would be able to measure the clear plastic I suppose, but even a probe taped to the cover is going to be influenced by the tape and the probe as they each absorb energy and get hot themselves, thereby tainting the actual temperature of the plastic.

insp1505 wrote:
That's really not the issue here though. The issue is that the heated object (the inner plexi-glass layer) wasn't allowed to cool or transfer heat off itself fast enough to avoid being damaged because I kept the shade closed which trapped the heat inside.

I find fault with that logic and here's why; if the sun's energy was able to transport through the clear plastic and heat up the object thermometer, then the foil reflected that same energy back through the plastic out into the atmosphere. Think about it; how could the energy that caused the air in there to heat up to those temps NOT instead be also reflected right back out the way they came in? Now, if the OUTSIDE of the clear plastic was hot, I'd say sure; the plastic absorbs energy from the sun, but that layer of plastic didn't heat up, it allowed the sun's energy to pass through to the inside where the foil reflected it and where the plastic, again, passed the sun's energy right back out through the plastic.

insp1505 wrote:
Only the inner layer of plexiglass warped because it had a superheated air mass between it and the outer plexiglass layer and also between it and the shade that didn't transfer the heat away efficiently enough to keep the inner layer of plexi-glass from becoming too hot and warping.

How can you say the air between the layers got hot at all? You didn't measure it. Again, the sun's energy transferred BOTH layers of plastic and heated that thermometer because it wasn't transparent. The rest of the sun's energy passed through the clear plastic and reflected off the foil and then right back out.

I could continue on with rebutting your arguments, but it would not serve any more purpose if the arguments I've already provided are disputed.

I retired from the electric company and I've spent a bit of time working on solar plants and exploiting sun energy. One last argument for my opinion; Dual pane windows in just about every house should convince you that sun's energy will pass through both layers of glass without slowing down it's heating effects when it's just atmosphere between the panes. The technology advanced with the discovery that either a vacuum or inert gases could insulate the sun's heat from getting through the air gap between the panes. With air, heat moves back and forth between panes of clear panel. Air is not trapped and super heated.

I don't know what caused your inner layer of plexiglass to crack. I do know there are way too many of these hatches out there that do not crack from suspected heat in a whole lot hotter climates than yours was exposed to. If your hypothesis was correct, there would be a lot more broken covers.

Please don't read anything more into my post and reply other than as a pleasant discussion while sitting around a campfire sharing a couple beers. I could be totally wrong, but I don't think so.

Cheers!!