2nd time failure on Onan 5.5 LP

[crussian]

Hello all - I have a 345RS Oakmont. I had a 5.5 Onan genny installed (dealer recommended size). Twice, i have fired it up and let it run for 5 mins or so, then turned on the front air, waited for it to cycle, blow cold air. Waited, emptied refridgerator, came back, front air still running, went to back bedroom, turned on air. Heard it come on, cycled to blow cold air, and left to do another cleanup duty. Anout 20 minutes later i came back, genny was running and both air conditioners were shut down.

Only other 110V running was fridge. Was i sold a bad bill of goods saying the 5.5 would power the whole coach?

Thanks in advance.

C&J

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[crussian]

Also need to add that one 30 amp breaker was thrown.

C&J

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[richheck]

The Onan 5.5 is capable of supplying power to a total of three AC units in the Landmark 365 coaches as long as the generator is the model with two 30 amp breaker circuits. There is a model of the Onan 5.5 series that has one 30 amp and one 25 amp breaker circuit.

You should not be having issues with the Onan 5.5 if your coach is wired correctly. Now comes the fun part in figuring if you have wiring issues. My first impression is for some reason both of your AC units are on the same circuit, where each should be on its own.

Sometimes owners forget that they have their water heaters on the 110 circuit in addition to the fridge.

 

[danemayer]

Hi Crussian,

Most likely you just have too much stuff on 1 power leg. There are 2 hot legs coming off the generator, each supplying up to the number of amps for the respective circuit breaker on the front of the generator. So if you tripped a 30 amp breaker on the generator, the stuff on that leg may have been pulling more than 30 amps.

You may have to take a look at your main circuit breaker panel to determine how things are wired. For example, if both A/C units are on the same power leg, you'll likely have a problem and will need to rearrange. As mentioned, the electric element on the water heater pulls a lot of power. The Power Converter that runs the 12V DC lights and keeps the battery charged is a hidden load that usually draws only a few amps, but I'm told the larger units can peak over 15 amps at times.

On many circuit breaker panels, looking from left to right, you'll find two 50 amp breakers tied together - incoming power. Each of those supplies power to 1/2 of the other breakers in an alternating sequence. So it may go 50 (L1), 50 (L2), 15 (L1), 15 (L2), 20 (L1), 20 (L2), etc. Other boxes will have the 50s in the center and L1 circuits on the left, L2 circuits on the right.

Take a look at your breakers to see what's on each power leg.

As for how much you can run, we've run our Landmark on the generator many times and have used both air conditioners, the water heater, and everything else without any issues. But we've probably been running right on the edge of what the generator can do.

 

[crussian]

Will check breaker panel. Hopefully will all be labeled. Thanks.

C&J

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[carl.swoyer]

Set you ac's 2 degrees apart. This will keep the units​ from cycling on at the same time. Also if your hot water tank is on electric put it to LP or off.

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[carl.swoyer]

I also changed the 20 amp breakers to a 30 amp breaker. So my 5500 Onan generator runs quietly with two 30 amp breakers.

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[porthole]

Onan rep at the rally answered the why some 30/30 and some 30/20

IIRC, the 30/20 was for older smaller motor homes that were hard wired. His answer if you have that version - swap out the breaker

 

[Jim.Allison]

I have a BC3650RL, and my 5.5 can run everything on my coach. Never had a problem. You have an undiscovered issue, that has nothing to do with the size of your Onan unit. 30a per leg is a lot of amps to work with.

I'm thinking that you are entering the coach and inadvertently firing up everything, the fridge, the water heater is cold so both elements light up, the charger/converter is trying to charge the batts, and you want it to be cool so you switch on both A/Cs. so when you fire up the whole system, you are throwing everything at the generator at the same time.

Use LP for the water heater and fridge, it's more efficient.

 

[avvidclif]

Onan rep at the rally answered the why some 30/30 and some 30/20

IIRC, the 30/20 was for older smaller motor homes that were hard wired. His answer if you have that version - swap out the breaker

????? I thought all Onan RV Generators were hard wired, never seen one with a plug. Mine came with 2 30's.

 

[porthole]

????? I thought all Onan RV Generators were hard wired, never seen one with a plug. Mine came with 2 30's.

Maybe someone that was sitting in the front of the room could hear his description better, but the old motor coach thing seemed to be the gist of it.

The good news down the road is they have fuel injected inverter gas genny coming in about two years.