A/C question

[kingdaddy]

My Monty has 2nd A/C with the front bedroom unit also ducted. When the unit thermostat calls for cooling, do both units come on or only when high demand calls for it? The question came up when trying to decide what my needs would be for a generator to run the A/C. If both units come on, seems like the typical size gen. wouldn't handle it?
Anyone have experience with this?

[DAR]

we have a 5500 watt generator and we have not had any trouble running both ac's with the generator. I have never checked the ac's to see if one is a 13500 btu unit I am pretty sure it is though, if you had 2 15000 btu units you might need the 6500 watt generator like some folks with the newer Monty's have.

[WeBeFulltime]

On our 2012 3585SA that has 2 factory installed A/C units each one is controlled independently using one thermostat with 2 zones. You can select to have 1 or both on and select the temperature you want in each zone. The main units sensor is in the thermostat and there should be a sensor somewhere in the bedroom ceiling that is connected to the secondary A/C.

[1retired06]

Ours is also independently thermostat controlled.

[DQDick]

Since we use two Honda generators, if we are on generator we shut one AC down and close the dump on the other one and let it cool the whole rig. Works well in most temps I want to camp in. If it's going to be in the 100's we'll find a plug in somewhere.

[kingdaddy]

Hmmm...I think I will play around with the thermostat and see if there are two zones, that may allow either just one or both units to run.
Gotta dig out the paperwork and do some more research too. Thinking of getting a Yamaha 3000i gen. but would only run the 13,500 unit if I can do that.

[dieselguy]

I'd bet you have something in your A/C contols that separates the operation of the front air from the rear air. I've never seen a dual air unit that does not. If they were to ever come on together ... it would draw a boat load of amps. Although you state that both are ducted ... are the contols to your front air on the ceiling grill itself?? When you say "typical size" generator ... you'll need a 5K plus unit to support both A/C's and other small load devices most always on.

[mhs4771]

We had a 2010 Montana 2955RL that had the dual zone T-stat which allowed us to control each AC independently using the single T'stat.
We have dual 15K ACs in our SOB and our 5500 Onan will run them both without a problem.

[kingdaddy]

Ours has a pretty decent thermostat (Dometic) so I need to look at it closer for the feature mentioned about dual zones and running either one or both.
My goal would be to operate just one when using the generator, not sure if they are both 15k or if one is a 13.5?
There are no controls on the front unit at all, it is flush to the ceiling with no outlets (our first Monty had the optional 13.5 with local controls and outlets).
Once we move back in (our house is in escrow, no "new" house yet!) I will finally have some time to look into these things...

[rohrmann]

If you select zone 1, you have heat or A/C options, and this is the main A/C only. Go to zone 2, and this will be the second A/C only. You can have zone 1 off and zone 2 on, both on, or reverse having zone 1 on and zone 2 off. You have full control over which A/C runs.

[kingdaddy]

Thanks Bob! That is very helpful... any idea whether they would typically use 15k A/C for both? Seems like they would use a 13.5 up front but from the ground they both look the same?
I'm thinking at some point I would kinda like to change the front unit to a new, low profile unit.

[rohrmann]

Ours, as optioned from the factory, has a 15K main A/C and a 13.5K second A/C above the bedroom. Yes, from the ground, they look pretty close in size. We had our bedroom A/C replaced within the first year under warranty, and wish we could have had it replaced with a low profile unit, but don't think they were available back then. I don't think you will gain much, only 1.5K, by changing the front unit out if it's still working.

[kingdaddy]

I would stay with the 13.5 up front but just possibly change to a newer low profile, possibly more efficient unit? From what I understand, a Yamaha or Honda 3,000 watt gen. should be able to handle the starting and running load, but would have to be careful with adding more load (e.g. microwave, washer/dryer etc.)
As always, the research continues...thanks for the input!