I am trying to size the smallest emergency generator for hurricane
season(s) here in Florida.
Smaller size means less fuel, less weight, less noise.
I will start the A/C and keep it running and then flip the breaker for
the refrigerator.
I believe that 6.5 hp 3500-4000 watts would do it.
Do you have any experience with a small emergency generator?

I have a 4kw generator that easily supports a gas furnace, refrigerator and
lighting. I'm certain it would not carry my central air conditioning.
I don't know what size you need to start your window a/c. Compressors start
hard.
Better mpg, smaller size, less noise are claims made by the newer inverter
based units that can slow down under light load.

I have a generator slightly larger than the one you are looking at.
The only thing I have used it for is for job-site tools (compressor,
drill, saw), so I have not taxed the capacity.
I do have a 5000 BTU A/C unit -- it draws about 10 Amps steady-state,
but I don't know what the startup current is.
Between your refrigerator, and small A/C unit, that's about 20-25 Amps.
The 33 Amps capacity of the generator-in-question should be
sufficient. If you can't start the A/C with another load, then I would
do as you suggest and start the A/C by itself, before applying more
load.
Here's to hoping you never have to use it.
Tom

The problem is the refrigerator. Last years I tried to run one in my truck
with self made inverter. The thing worked perfectly for all tests but on the
road it failed again and again.
The reason therefore is, that startup current of refrigerators depend
strongly from temperature outside. The higher the temperature, the more
important is the refrigerator and the higher the pressure of the cooling
substance. Higher hydraulic pressure needs high motor torque resulting in
extremly high startup current.
From the same reason, service technicians are not happy about hot summers.
Most refrigerators and mainly air conditions are dimensioned for
temperatures up to 35 degree celcius. In my truck I easily had 50 degree and
more. This makes the startup current so high, that the motor protection
breaker blows out and the cooling in critical situation fails.
Assume all, the generator should be able to supply 6-8 times more capacity
without dropping the voltage for secure startup of cooling devices. If the
voltage drops 10% at startup, the theoretically available torque of async
motors drops much more (up to 50%). A solution could be refrigerators
working with frequency inverter what can start with a F/U ramp but I did no
tests with those expensive devices. I tackeled to buildt one myself but this
is difficult since the compressor motors are hermetically closed due to
noise reasons.

5000 BTU air conditioner (running on 120VAC) will draw about 30~35 amps
starting current for about 0.2 to 0.4 seconds, then draw 6~8 amps
running current.
Refrigerator start up current is about 600% of running current for 0.2
to 0.4 seconds. Therefore, if your refrigerator really draws 11.6 amps
of running current, then start-up current will be about 70 amps.
Worst case will be when both A/C and refrigerator starts at same time,
total start up current will be about 100 amps and cause the 4000 watt
generator's output voltage sag and either A/C or refrigerator (or both)
not to start.
Since a typical 4000 watt generator has split phase output (120/240V),
only 2000 watt is available for 120V, it would be safe to move upto
something like a 7000 watt generator (then each 120V output will be
rated at about 30 amps or 3500 watts, and one 120V phase could power
the A/C and the other 120V phase could power the refrigerator).

5000 BTU air conditioner (running on 120VAC) will draw about 30~35 amps
starting current for about 0.2 to 0.4 seconds, then draw 6~8 amps
running current.
Refrigerator start up current is about 600% of running current for 0.2
to 0.4 seconds. Therefore, if your refrigerator really draws 11.6 amps
of running current, then start-up current will be about 70 amps.
Worst case will be when both A/C and refrigerator starts at same time,
total start up current will be about 100 amps and cause the 4000 watt
generator's output voltage sag and either A/C or refrigerator (or both)
not to start.
Since a typical 4000 watt generator has split phase output (120/240V),
only 2000 watt is available for 120V, it would be safe to move upto
something like a 7000 watt generator (then each 120V output will be
rated at about 30 amps or 3500 watts, and one 120V phase could power
the A/C and the other 120V phase could power the refrigerator).

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