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Old 09-15-2013, 01:45 PM   #1
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Looking to run three A/C units off of the generator

Title pretty much says it all, but let me try to make things a little more clear.

2008 National Pacifica 40'. Came with the Basement A/C 2 stage unit. It has never kept the coach cold during the 90+ degree temps. Throw in Texas 100+ heat and we would sweet off the pounds with vigor.

Solution was to have a 15K Coleman roof A/C unit mounted in place of the Fantastic Vent. The power cord was run down an interior wall to the basement. From here we have two choice as to where to power it up. While on the road we plug in to the outlet that was intended for the in coach vac system (the in coach vac system does have it's own 115v breaker in the panel box) if desired to use it. However, we have to remember to set the power switch in the rear power selection to 30 amp. Not this does not set the coach power level to 30 amp, it only keeps both stages/compressors from coming on with the basement A/C unit. We were told that the generator may be up to run all three A/C systems, however that the initial power up of the compressors would most likely be too much and trip the generator breakers or worse case burn the system up.

When we are plugged into shore power, I plug the 50 amp cord in, set the switch box to 50 amp to be able to power both basement compressors. I then via an extension cord plug the roof air unit in to the camp ground power 20 amp out let and run all three A/C compressors.

OK, now after all that ground laying work and explanations here is my question. I was looking on Ebay and came across a "RV Hard start up kit"
RV Coleman Dometic Duo Therm Air Conditioner Hard Start Kit Tips Instructions | eBay
If I were to install this on the roof unit, do you think that the generator would be able to run, start and cycle all three a/c compressors with out creating a problem.

I would like to say yes, it would work, but then to be honest I have no idea or electrical smarts to back this up in theory. Only positive hopes of it doing so.

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Old 09-15-2013, 03:07 PM   #2
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No mention of the gen set size , unless I missed it , that's been known to happen.
3 compressors I'd say 10,000 watt required.

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Old 09-15-2013, 03:31 PM   #3
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Yes, I knew I had forgotten to add something. Onan diesel 8,000KW, 66.7Amp
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Old 09-15-2013, 03:40 PM   #4
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it might work, but you couldn't run anything else. if that 15,000 btu unit is not ducted, it will blow a larger volume of air
Ernie Ekberg, Prevost Liberty XL Classic
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Old 09-15-2013, 03:54 PM   #5
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The 15K unit is installed in the center kitchen just ahead of the hallway to the bed and bath room and is non ducted. And yes it does blow a great amount of air. Of course when on the road I am running the larger side of the basement air, the 15K ceiling air and dash air, which does a pretty good job. I guess I am just looking for more than what I may really need.

It sure wouldn't be worth going for a new larger 10K generator as far as cost goes. Thought that maybe my finding a way to lessen the start up amp draw combined with a staggered start of the units things may work out.
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Old 09-15-2013, 03:58 PM   #6
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As a side note, I did have my residential A/C guy take a look at the basement air system. His suggestion was that I may be able to improve the performance while on the road by fabrication of a small air scoop along the grills of the air intake on the side of the motor home. His theory is that while at highway speed the air is being stream lined down the side of the coach, and there for not being allow to take in enough fresh air to the system.
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Old 09-16-2013, 07:15 AM   #7
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I have the same gen and basement air. I added a 15000 top unit and wired it in to the washer dryer circuit. You can run all of it off of gen (or at least I do). The only condition is do not try to run top a/c and washer dryer breaker will pop at bedroom panel.
I think the problem with the basement air traveling is that the air intake for it is in the very back of the bedroom and it sucks hot engine air in. As the motor is right next to it . An a/c can only lower intake air temp down a limited amount. All the insulation that is around the top of the engine can only help so much as that thing back there make a LOT of heat.
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Old 09-16-2013, 09:39 AM   #8
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I have a 2008 Pacifica w/basement air, I installed a 13,500 roof top unit, (cut new hole) did not want to give up vent in kitchen area. I wired to the block heater circuit. I have run all 3 on shore power w/out any problems. I do not run the basement air while on the road since installing the roof top unit (due to the engine heat). I have ran all 3 w/the gen just to check the system out.
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Old 09-16-2013, 04:42 PM   #9
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You should be OK with your 8K watt genny. You may need to manage the power some such as staggering the the start-up of the AC units as they draw significantly more power on start up than running watts. You may also have to avoid using a convection microwave oven (if you have one) or hair dryer etc. Smaller items such as TV's etc draw little load. Also did you buy an energy efficient 15K BTU unit? If so you're that much better off. Stay cool!

2007 Allegro Bus 42 QRP, 400 ISL now 2017 LTV Serenity on a 2016 Sprinter chassis
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