What is the most efficient rooftop A/C?

[belfert]

Which rooftop A/C unit is considered the most efficient on power?

I'm considering three 13,500 units instead of two 15,000 units, but I need to run all three on a 7,500 watt generator.  I probably would have gone a little bigger on the generator, but I got a good deal on this one.

Briqn Elfert

[TomCat]

Hey Brian,

I don't know if my units are the most efficient model available, but I installed two Coleman Mach One, PS1, Power Savers rated at 12690 btu's each, that draw 9.6 amps of 120v each.
They make about as much noise as you'd figure they would, but really do an awesome job of cooling my coach in a hurry. The forward unit is far enough forward, that coupled with the drivers fan, works great as the drivers AC, in spite of the large greenhouse up front.
My genny is a 5.5kw propane Onan, but easily runs everything in my coach.

Jay
87 SaftLiner

[Nick Badame Refrig/ACC]

Brian,

Last April or May's FMCA Mag. had a comparison chart on roof tops.[ I'm not quite sure exactly which month, don't hold me to it!]

Mabe you have a copy saved? But they list all mfg's .specs.

Your 7,500 watt gen is probably border line for 3 roof's, Just concider that when a compressor starts up, it may draw as much as 3 times

it's normal amp draw for a brief moment! Do The AMP math. You would have to watch when you first turn them on, to stage them.

Also concider, the hotter is out the more amps they draw over the rating plate. [they usually rate compressors at 85 deg, F]

Hope This Helps!
Nick-

[FloridaCliff]

Brian,

Nick is correct on the 7500 being right at the edge for the three.

The Carriers I have(ducted) have a switch to set them up for a delayed start.

I think you can do three, but I would confirm that.

[Kristinsgrandpa]

  Also remember that for every 1000 feet of elevation above 500, deduct 3.5% of your kw rating and for every 10deg. above 80 (I think) deduct 1% of your kw rating.

Of course going thru the mountains it is usually cooler so it might not be as bad as it sounds.

Ed