Improving A/C performance

[Stevemc]

Yes thanks for all the discussion and input everyone. It's an interesting discussion.

[SailorSam20500]

Well, just to chime in again. Once the unit is running and pulling in air, there may not be a bunch of difference. But if the unit is cycling on and off, the white cover should keep the hardware temps down. So there should be some benefit initially. FWIW, for my mothers S&B AC unit, based on a write-up in the local paper, I built a white structure over her unit. During the afternoon it was in full sunlight. It seemed to help her - electric bill dropped a bit.

[dalford]

Originally Posted by stevejahr

I think this comes under the "it all depends" category...

There are two processes happening in the rooftop A/C unit:

1. Air comes up from the RV and goes through the evaporator. This compartment could benefit from being in a cooler environment so as to not absorb heat. I have read of folks insulating this portion of the rooftop unit with reflectix type foil/bubble wrap.

2. Air is pulled in from ambient and goes through the condenser. The air passing through needs to absorb heat so there is some rationale that cooler air would be better. But since it is pulled in and moving I doubt that cover color really has much effect here. The mister jets would be more effective... I have seen kits to do this on home A/C lately. I have always wondered though if this would not add lots of corrosion and/or mineral deposits and thus shorten the lifespan of the condenser?

No air from outside is drawn into the RV....

[stevejahr]

Originally Posted by dalford

No air from outside is drawn into the RV....

Agreed. I was not saying that outside air was drawn into the RV, only drawn into the A/C unit on the roof to pass through the condenser and back out again. The A/C works as a heat pump and removes heat from the RV air passing through the evaporator and then must lost that heat to air passing through the condenser.

[silver]

I have a 40 foot motorhome with two 13500 A/Cs. Five years back I insulated the A/C covers as many have recommended and saw little difference in performance. Last year I painted just the top of the black covers white and the shower skylight white. I can now keep the coach comfortable with just one A/C in 95 degree heat when I can only get 30 amp service. I say painting the top of the covers white works.

[Stevemc]

This thread has been very helpful for me. I don't know much about how air conditioners work but I just know I like to be able to stay cool and I'm always concerned about the wear and tear when the A/C's run constantly to keep up. It's great to have so much knowledge that is available on the forum and so many folks willing to share it.

[Jay2504]

On our 2504s I put reflitx on the cold side of the roof a/c. I also put on a hard start capicator at the same time. I wondered the same thing about putting a black cover over something that I am trying to cool. I am going back up there and paint the top of the cover white,seems like a good way to make the roof unit a little cooler but from the ground it will still look black. I also agree that misting would help but could leave deposits on the condenser. I am a retired HVAC tech on Kenworth trucks, but that is a different ball game. On the inside I put reflitx covers on the front vent and in the shower sky light. That made a big difference. Keep in mind the a/c has always kept things cool in our camper. Based on the size camper that I have I could see how people with bigger units could have trouble. Jay

[pt1655]

Lots of great posts on this subject. Being retired and my wife is not, I have the time to think of lots of projects to do to our trailer. I just got done painting our black refer vents (top and side) & A/C covers white and hope it makes a difference here in Arizona. It wasn't much work; the prep time took more than the painting.
Who else has a fun project I can try?!!
Happy Camping!!

[Retired JSO]

The new units have very little performance increase from the shroud being white against black. All new units separate the cool from the hot exposed temperatures by molding the internal unit in styrofoam thus using a thermal unit between the condenser and evaporator. Outside vs inside temperature is the killer with our units. Now shading the entire camper is a different horse race.