Roof Top A/C question?

[billg27]

For the van and Sprinter drivers who have installed roof top a/c, what have you noticed for fuel economy loss? Would the unit be more aero dynamic mounted toward the front of the roof or farther back toward the rear of the roof? Thanks!

 

[guido4475]

For the van and Sprinter drivers who have installed roof top a/c, what have you noticed for fuel economy loss? Would the unit be more aero dynamic mounted toward the front of the roof or farther back toward the rear of the roof? Thanks!

Absolutely no MPG change with my 15,000 btu Heng's brand ( Manufacturer of Dometic) rooftop a/c unit on the roof.I put mine in the first 4 ft of the roof so if I have the last 8 ft occupied by a load over the weekend, etc, I can drop the curtain at the 4 ft mark inside, and have the bed behind the seats, side to side, and still use it while loaded, instead of cooling the freight if it was further back.My roll-up door played a part in this as well. It weights 82 pounds, by the way.

 

[kg]

Installed a Coleman 9200 btu favoring the rear half of the van. Wondered myself what the milage downside would be. It seems that there is little if any difference.


Stay safe
kg

 

[westmicher]

If you must have a roof mounted air conditioner, it should be as close to the front as reasonably possible. If you've ever seen wind tunnel smoke trails over a vehicle, the windshield clearly redirects the airflow primarily over the vehicle, increasing air pressure over the top of a tall van more than you can imagine! However, it takes a few feet for most of the redirected air to flow back to the roof surface, creating a bit of a bubble of relatively lower air pressure near the front of the van roof... where you should place a rooftop air, if you must.

In our experience, we now know the roof is the worst place to install things that obstruct airflow... we believe decreasing MPG up to 6-7%, depending on size & placement.

 

[xiggi]

I have a high profile ac unit on a sprinter close to the front. I did see a drop of about 1/2 mpg but at the same time installed a vent fan with a taller weather cover, a tv antenna and also a rear rack with generator. So not only did I increase height I increased constant weight to the van.