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Ask Dave: Can I run both roof AC units on 5200 Onan?

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses running two AC units.

Dear Dave,
I have a 30-amp control box with a 30-amp transfer switch. I installed a soft starter on the existing AC unit and plan on installing another AC; and I installed a 5200 Onan to handle the power. I had planned on upgrading my control panel and transfer switch to 50 amp, but the new control panel is 3″ higher and won’t fit. I read your article about running the generator to power one AC unit. Are you depending on the 30-amp breaker on the generator? Do you see any other options here? I plan on installing another soft starter on the second AC too. —Roger

Dear Roger,
Are you sure your generator is a 5200 and not a 5500? Either way, typically the Onan 5500 would have a main 30-amp circuit that would power the distribution center and a second 30-amp circuit breaker that would go directly to the back roof air conditioner. Some of the older models and 4000 models would have a 30-amp main and 20-amp secondary, but it was still enough to power both roof air conditioners.

There would be a switch inside labeled AC Front/Back if the unit had two roof air conditioners. You would direct the switch to the front to run the living room roof air conditioner when plugged into shoreline power through the distribution center, and to the back to run the bedroom air conditioner off 30-amp shoreline power through the distribution center. To run both, place the switch to the front which brings power from the distribution center and starts the generator. Your Automatic Transfer Switch (ATS) senses power from the generator and switches to allow power from the main 30-amp circuit of the generator to the distribution center and the second circuit to power the back roof air.

SoftStartRV

With that said, there have been several reviews, articles, and tests done on running two roof air conditioners on a 30-amp circuit using the SoftStartRV™ product such as this article from RVtravel.com featuring a video from electrical expert Mike Sokol here.

And here is an article about the SoftStartRV written by Mike Sokol, as well.

One thing to keep in mind. The SoftStartRV product just limits the initial start-up amps of a roof air conditioner. It does not lower the operating amps, which is important to know so you can calculate the amp draw from other appliances being used in your rig.

Energy management is important in an RV

In our homes, we turn on appliances, crank the heat or AC, and plug in all types of gadgets without concerns about the power needed. In an RV, energy management is important and a better understanding of components is important.

I would recommend contacting Progressive Dynamics or Parallax Power Supply to see if they have a 50-amp configuration that will work in your space. You probably have an all-in-one unit now with the distribution center and the converter together. They have models with a separate converter that might work, as I doubt you want to run the generator all the time when needing both roof air conditioners. The distribution panel is compact and the converter can be placed underneath cabinetry or in a storage compartment.

Read more from Dave here

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Jesse Crouse
6 months ago

My 1998 Bounder had a load management system that shed one A/C when the other wanted to start and allowed both to run after the start up draw was done. It had an Onan 5500 genny and 30 amp service.

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