Air Conditioner Question

[Houndie Dog]

Hi folks,
I was wondering if anyone knows how much amperage a new rooftop A/C draws?
We are going out this weekend and it is supposed to be very hot. I want to run both A/C's but the campground only has 30 amp service.

I know the quickest way to figure it out is if the breaker trips or not, but I just like to know the details of what I have to work with.

Thanks and hope everyone has a great holiday weeked............
Grant

[pjhansman]

Assuming you have at least 13,500 btu and more likely at least one 15,000 btu AC unit, you could draw as much as 15 amps per unit, and more at start up.

Combined with your converter, running both on a 30 amp circuit will be a challenge.

[Bob Landry]

The 13.5 will draw around 12A. a 15 around 14. It will be difficult to run both on 30A.

[hankaye]

Houndie Dog, Howdy;

Here's a suggestion, use the one in the bedroom. You can always throw an extra cover on but you can only remove but so many.
Cool air drops so will flow from bedroom to back end. if you have a fan use it to circulate the cooler air to the furthest corners.

only a suggestion ...

hankaye

[mikell]

460Get a couple of plug in volt meters and put one on each circut and don't get below about 105 volts. We lost an ac unit a couple of years ago because of a 95 volt circut. The plug in meters are less than $10 each

[Johnnyfry]

Remember that the Freon pressure is dependent on the outside ambient temp. That means that start up in hot weather (naturally just when you need it!) takes more juice under those conditions.

A 2 kW genset may start it just fine at 70 degrees but yak at 95 -- naturally, when you need it more.

John

[Bob Landry]

Remember that the Freon pressure is dependent on the outside ambient temp. That means that start up in hot weather (naturally just when you need it!) takes more juice under those conditions.

John

No, it's not. The refrigerant circuit is closed and can not be affected by ambient temperature. The current draw of the compressor will vary by one amp for every 10 degree change in ambient temp, but that does not affect pressures. That's how Dometic says to check to see if you are properly charged. The temperature that WILL affect pressures is inside ambient temp. In maintaining a delta of approx 20 degrees, the evaporator(suction side) pressure will vary with the return air temperature, but head pressure will remain relatively constant.

The compressor does draw LRA when starting, but that only occurs for a small fraction of a second and is not long enough in duration to enable you to measure it without a VOM with a hold function. Before the circuit breaker has time to sense this and trip, the compressor will sense the phase difference and the run capacitor takes over. Under normal conditions this will not cause difficulty in compressor start-up.

[Johnnyfry]

Sounds reasonable to me, I stand corrected.

John

[Houndie Dog]

Thanks for the replies..... We had a 109 heat index this weekend and it was very hot. Trying to get the most from the 30 amp service I had available this is what worked for me. I ran the refrigerator and water heater on LP instead of AC. I ran the 15000 BTU AC on medium and ran the 13000 BTU AC on low and the only problem I had was when the wife tried to heat up something in the microwave......tripped the breaker. After resetting the breaker and explaining to her the concept of load shedding, I had no further problems. Both AC's ran on 30A this way all weekend and kept the trailer cool. When it was dinnertime, I would just shut off the bedroom AC so we could cook. At night I woud reverse the settings running the bedroom on medium and the living room on low.

[Bob Landry]

That's a reasonable approach. A lot of people just don't understand 30A systems and energy management. And, you have to manage it. Fortunately, he ability to switch the high draw appliances to propane when needed makes that a lot easier. There are still people who try to run everything at once and then schedule service when they get home because the breaker kept tripping.