Can't Make Up My Mind on an AC Unit

[SilverMiette]

So I'm pretty indecisive at times and this is one of them - I need someone to decide for me, or at least push me one way or the other. I'm redoing a 1964 Sovereign. I painted the tongue and bumper dark gray, have black glossy rims with VTS cones and chose the smoked vent covers, including the astrodome from Inland RV. So I have that dark gray/black thing going.

The decision I have to make is the air conditioner. I really want low profile because a big box on top just looks off to me. I also want it in black - a white unit would seem like it doesn't fit the theme. But I also don't want to pay an arm and a leg (but I could). Looks like I can get a Dometic Brisk in black. Or I can get a Coleman low profile in black for roughly double the cost of the Brisk. I didn't see a black Dometic Penguin II but a white one is about in the middle of the two, maybe closer towards the Coleman.

So, which one? Is the Coleman worth the extra? Do the Brisks really dominate up there with the extra 5 inches over the Coleman? It's really about aesthetics at this point.... and noise level. The quieter the better obviously.

Any help is appreciated. Am I the only one with this aesthetic indecisiveness with the AC? I've read the technical indecisiveness posts but haven't found an appearance based discussion.

[J. Morgan]

Why not buy the one you want and have the cover painted with automotive paint?

[J. Morgan]

I would have been forever finding a red air conditioner...

[truckasaurus]

How about buying the low profile unit and taking for a vinyl wrap? Probably very cheap, removable when you decide to and you could most likely get it in silver, grey, black or maybe even mirror foil look….

[Protagonist]

Originally Posted by J. Morgan

Why not buy the one you want and have the cover painted with automotive paint?

That is an excellent idea for anybody, even those who want a white one. Painting the shroud slows down the inevitable UV degradation of the plastic, and will make the AC shroud last longer.

[idroba]

Since no one will ever be up close to the shroud, even painting it with Krylon paint for plastics should work just fine. I have had excellent results with that paint. A lot cheaper than having an auto paint put on it.

[Minno]

We bought a Penguin in white and painted it gray with Krylon paint. That was 2 years ago, and the paint has held up just fine.

Chris

[kmaggard]

Do yourself a huge favor and get one that is thermostat controlled. Then you do not have to listen to a fan blowing all night! Manufacturers have been slow at picking up this idea but they are finally catching on.

[jdalrymple]

I know a lot of folks like the black color, but I always wonder how much cooling power this costs when one is parked in full sun.

Even a 15K BTU unit is only limited to reduce temps by less than 30 degrees, so if the area compressor is working in is 75 degrees warmer because of a black enclosure, how much cooling power is one giving up?


Regards,


JD

[idroba]

Originally Posted by jdalrymple

I know a lot of folks like the black color, but I always wonder how much cooling power this costs when one is parked in full sun.

Even a 15K BTU unit is only limited to reduce temps by less than 30 degrees, so if the area compressor is working in is 75 degrees warmer because of a black enclosure, how much cooling power is one giving up?
Regards,
JD

The higher temp you mentioned would not be sustained as soon as the fan turns on. The heat would be blown out almost immediately and the temperature of air through the exterior coils would drop to ambient outside air temp. The surface area of the shroud that is available for the sun to work on and increase heat is minimal in comparison to the volume of the air passed through the unit.

Bottom line, the shroud color will make no cooling difference on any rooftop AC unit.

[Siegmann]

I always thought a darker shroud would make a difference, but Idroba's argument seems sound. Anyone else have an opinion or experience on this issue?

[Protagonist]

Originally Posted by Siegmann

I always thought a darker shroud would make a difference, but Idroba's argument seems sound. Anyone else have an opinion or experience on this issue?

The shade cast by the shroud is more important for lowering the temperature of the coils than is the color of the shroud for raising the temperature of the coils. Considering how many openings there are in the shroud for ventilation, heat won't build up in the shroud anyway, unless it's a completely windless day.

[jdalrymple]

I understand the theory you are applying, but still wonder about true application.

Space under a black sunscreen is warmer than space under a light color, even with a fan moving air.

It would be interesting to see real data.


Regards,

JD

[ROBERTSUNRUS]

Hi, buy the air conditioner of your choice and buy a life time shroud in black or white from Icon-Direct. Also, too many times, people say you should buy this type/size air conditioner because of where you live; That's fine if you only camp in your back yard. We travel and our trailer needs to work where ever we go with it.

[idroba]

Originally Posted by jdalrymple

I understand the theory you are applying, but still wonder about true application.

Space under a black sunscreen is warmer than space under a light color, even with a fan moving air.

It would be interesting to see real data.


Regards,

JD

There are many assumptions that have to be made to do the calculations. Those such as volume of air moved through the condenser, the area exposed to sun, the max heat from the sun, the conduction and reflectivity of the plastic and so on. I made some of the assumptions and the worst case numbers I can come up with show less than a 1 degree effective temperature difference would be generated by a light vs dark cover. That is if it was 100 F outside a black cover would cause the air moving through the system to be 101 vs a white cover. My numbers all err on the conservative side, that is making it as bad as I can come up with. I would be very surprised if you could measure any difference in the field using expensive temperature measuring devices.

And without going into a college level course on heat transfer, I will not defend my answer with my assumptions and math calculations....LOL. I can only say "trust me" and duck.

[SilverMiette]

Thanks for the info so far. How bout the size... anyone regret spending more on low profile vs. standard height?

Sent from my Nexus 4 using Airstream Forums mobile app

[Siegmann]

Going back to the question of a black shroud. It seems like the biggest impact could be during the initial use of the day. I'm thinking that the +/- 100 lbs of refer up on the roof would get hotter under a black shroud. When you first start it up you have to cool down many of the parts-- the starting temperature of the refrigerant, copper coils, fan motor, fan blades, steel structure, etc. And on a moderate temperature day, where the unit cycles off 10-15 minutes at a time, wouldn't it have to do it all over again? Too bad I tossed my old cracked shroud when I got a new one. Could have painted it black and done some real world testing!

[J. Morgan]

The only part where accumulated heat will matter at all is the condenser.

Being that the condenser is made to effectively discharge heat as quickly and efficiently as possible.....

Well I say authoritatively that the difference between a black cover and a white cover is essentially nil.

Incidentally, on well designed units the condenser sits just inside the shroud. Air enters the unit with virtually no contact with the shroud, making the temperature of the shroud 99.99 percent moot.

I suppose some heat might be captured in the unit and radiate into the interior, this would be minimal, and I doubt that this would would influence cabin temperature a fraction as much as a closed window.

[jdalrymple]

Originally Posted by idroba

There are many assumptions that have to be made to do the calculations. Those such as volume of air moved through the condenser, the area exposed to sun, the max heat from the sun, the conduction and reflectivity of the plastic and so on. I made some of the assumptions and the worst case numbers I can come up with show less than a 1 degree effective temperature difference would be generated by a light vs dark cover. That is if it was 100 F outside a black cover would cause the air moving through the system to be 101 vs a white cover. My numbers all err on the conservative side, that is making it as bad as I can come up with. I would be very surprised if you could measure any difference in the field using expensive temperature measuring devices.

And without going into a college level course on heat transfer, I will not defend my answer with my assumptions and math calculations....LOL. I can only say "trust me" and duck.

I too ran some numbers on the subject, and came up with a bit more heat production than you mention. But, I concede that it may not make as much difference as I might have thought.


Lots of folks go to college to study all manor of subjects. It makes for a more well rounded world.

Regards,

JD

[perryg114]

If you have to paint the shroud black leave the top of it white. The operation of the unit probably won't care what color the shroud is but when it sits 99% of the time, that extra heat will age the electrical components. The sun can put out as much as 1400 W of heat per square meter. If you paint the top of the cover black, most of that heat will go into heating that AC unit and the components inside. Most of which are made of plastic of some sort. The fan motor bearings will most likely dry up with constant heat. Capacitors will fail sooner. The shroud itself may become brittle and crack from the heat. Or in some cases it might melt if it is made from thermoplastic.

Perry