What size generator do I need?

[RPT2015]

I spoke with Dometic about the AC Unit and they told me I needed a 4400W Generator to run 2001 Duo-Therm 13,500 AC .
That seems to be contrary to what I have seen others write regarding what they use to run a similar unit.

I was hoping a 2800-3000 watt would do the trick.

Any suggestions?

Thanks RPT

[Motor7]

Here are the specs on the 13,500 a/c unit:

FEATURES

B57915

B59516
Nominal capacity, BTU/hr.:
13,500
15,000
Installation type:
Non-ducted or Ducted

Electrical rating:
115V AC, 60 Hz, 1Ph
115V AC, 60 Hz, 1Ph
Compressor-rated load amps:
12.4
13.2
Fan motor-rated load amps:
2.7
2.7
SCFM, high-speed max./min.:
300/350
300/350
Heater amps/watts @ 120V AC:
13.7/1,530
13.7/1,530
Refrigerant 410A (oz.):
16
22

AC circuit protection:
(User Supplied) 20 amp time delay fuse or 20 HCAR circuit breaker Installed weight, lbs.:
72
74
Minimum generator size - 1 unit:
3.5 KW
3.5 KW
Minimum generator size - 2 units:
5.0 KW
5.0 KW
Thermostat/Control options:
ADB or Thermostat
ADB or Thermostat

I went through the same thing 7years ago and after the sticker shock of quiet portable 3600 watt gennys I decided to try a Boliy Pro:
Amazon.com: Boliy PRO3600SI QBlue RV Pro 3700 Pull Start Generator: Automotive

My buddy liked mine so much he also bough one & both have done the job very well for less than half the price of a honda or yamaha. I quickly found out that they do not like ethanol, so always run a ethanol killer in the fuel and run the carb dry(it has a fuel shut off valve) before storage.

[Gary RVRoamer]

For just one, or a pair of them?

Basically you need about 12-13 amps (about 1600 watts) to run each one, but near double that to handle the brief compressor start-up load, which pretty much doubles the amps for a second or two. You need a generator that can handle that brief high-load moment. So what you want is a the capacity for a sustained 1600w (per a/c) but a surge or peak capacity that doubles that.

[Ray,IN]

Originally Posted by Motor7

Here are the specs on the 13,500 a/c unit:

FEATURES

B57915

B59516
Nominal capacity, BTU/hr.:
13,500
15,000
Installation type:
Non-ducted or Ducted

Electrical rating:
115V AC, 60 Hz, 1Ph
115V AC, 60 Hz, 1Ph
Compressor-rated load amps:
12.4
13.2
Fan motor-rated load amps:
2.7
2.7
SCFM, high-speed max./min.:
300/350
300/350
Heater amps/watts @ 120V AC:
13.7/1,530
13.7/1,530
Refrigerant 410A (oz.):
16
22

AC circuit protection:
(User Supplied) 20 amp time delay fuse or 20 HCAR circuit breaker Installed weight, lbs.:
72
74
Minimum generator size - 1 unit:
3.5 KW
3.5 KW
Minimum generator size - 2 units:
5.0 KW
5.0 KW
Thermostat/Control options:
ADB or Thermostat
ADB or Thermostat

I went through the same thing 7years ago and after the sticker shock of quiet portable 3600 watt gennys I decided to try a Boliy Pro:
Amazon.com: Boliy PRO3600SI QBlue RV Pro 3700 Pull Start Generator: Automotive

My buddy liked mine so much he also bough one & both have done the job very well for less than half the price of a honda or yamaha. I quickly found out that they do not like ethanol, so always run a ethanol killer in the fuel and run the carb dry(it has a fuel shut off valve) before storage.

To the OP; read the Boliy specs. It produces more wattage than a Honda 3000 and only weighs 78#.
I really like my Boliy PRO 3600IS too. Immediately after purchase I experimented with our 40' 5er W/ both a 13.5 and 15.5K heat pump on the roof. It started and ran either in economy-mode. It would run one,and start the other-and run it too (eco off), without tripping the internal breaker.
Of course I'd never do that while camping, but good to know.

[Nunyadamn]

I have a 15k AC and use the Champion 3100w unit - bought from Costco. I had the 2000i Honda and it could not turn it on.

[nothermark]

FWIW without reading the specs on the other units. The problem with units like the Honda is that the Inverter cannot handle the peak starting load so it shuts off instantly. Real AC generators may momentarily sag the voltage and slow the rotation but then even out as everything comes up to speed. The sag and slow should not hurt the motor in the AC but could give you problems with other electronics with inadequate power supplies. You might not want to run them directly off the generator. OTOH you can also feed the generator to the converter to keep your battery bank charged and run your electronics off an inverter connected to the battery bank. That effectively gives you a constantly clean power source for the electronics.

[marcham]

For what it's worth, my Mach 3 plus 13500btu AC draws 9A max. In order for my Champion 3100 to start it while in economy mode I had to install a hard start capacitor. It seems your AC would draw about 16 Amps, plus any other load in the trailer. Inverter generators don't have very large surge capacity so you usually have to get one sized larger than your needs or turn the Eco mode off.

[Motor7]

My only knock against the Champion is the noise level....they are loud. My Boliy is very quiet even when running in non-economy mode. They also make one with electric start for $30 more:
Amazon.com: Boliy PRO3600SIE QBlue RV Pro 3700 Electric-Start Generator: Automotive

[vsheetz]

Originally Posted by Motor7

My only knock against the Champion is the noise level....they are loud. My Boliy is very quiet even when running in non-economy mode. They also make one with electric start for $30 more:
Amazon.com: Boliy PRO3600SIE QBlue RV Pro 3700 Electric-Start Generator: Automotive

I have the Champion 2800/3100 from Costco. It is very quiet. I think you may be thinking of a differing Champion model.

http://m.costco.com/Champion-2,800W-...00139466.html#

[Motor7]

Originally Posted by vsheetz

I have the Champion 2800/3100 from Costco. It is very quiet. I think you may be thinking of a differing Champion model.

http://m.costco.com/Champion-2,800W-...00139466.html#

Ah yes, I was thinking of the yellow one in the metal cage that are sold more as construction site gennys.

I am really surprised that the Champion will run a 13.5 amp a/c unit, since start-up amperage is very close to 3kw it's max...$800 is a great price then!

[shiggs68]

There are two important factors when considering the size required to run an Air Conditioner, not want others have done.

First, the surge requirement to start the compressor and second the steady state voltage level. In both cases, any reduction from normal will severely effect the life of your Air Conditioner. That's why Dometic suggested at least 4400 watts.

Yes, they will run at a lower size, but the compressor is straining and creating more heat to do its job.

[Gary RVRoamer]

The compressor "strains" only if the supplied voltage is low, i.e. less than the 120v in the a/c spec.

[Nunyadamn]

FYI - the Champion 2800/3100 is extremely close to as loud as a honda 2000i at idle in eco mode, and slightly quieter when not in eco mode. I did the test before I sold my honda.