Pardon my greenness. I am 100% a newbie when it comes to RV’ing. I have a 33 ft class C, 30 amp, that has a single AC unit. The fan in the bedroom is pre-wired for a second unit, so it should be easy to install, I live in Arizona so the second unit would be nice to have. Obviously, the issue is power, or more specifically startup power. I have been working with the math and 30amps is enough to run 2 AC units once you get past that huge initial startup draw. In doing some reading it would appear it should work just fine using products like easystart or softstart. I guess my question is, why are RV AC manufactures not including easystart/software capabilities directly into the unit? Or, are there actually units out there that does this and I can’t find them? It would seem like this would be a no brainier especially with the RV power limitation?

Because it costs money and generally they aren't needed. A 30 amp outlet is plenty to start a single air/con and a 50amp outlet is plenty to start 2 air/con units (or even 3 units).It's really only when you try to use an undersized generator or overload a 30amp outlet, where these units really become useful.Also running 2 air/con units is pretty marginal on a 30amp outlet. Keep in mind, 30amps is the nominal rating. Continuous output is limited to 80% or 24amps. You see a lot of burnt up 30amp plugs from people who think they have 30amps, so they are going to use 30 amps.

Strador wrote:Pardon my greenness. I am 100% a newbie when it comes to RV’ing. I have a 33 ft class C, 30 amp, that has a single AC unit. The fan in the bedroom is pre-wired for a second unit, so it should be easy to install, I live in Arizona so the second unit would be nice to have. Obviously, the issue is power, or more specifically startup power. I have been working with the math and 30amps is enough to run 2 AC units once you get past that huge initial startup draw. In doing some reading it would appear it should work just fine using products like easystart or softstart. I guess my question is, why are RV AC manufactures not including easystart/software capabilities directly into the unit? Or, are there actually units out there that does this and I can’t find them? It would seem like this would be a no brainier especially with the RV power limitation?I have a 50 amp fifth wheel so I think it is different, but my understanding in the 30 amp motorhomes is they run on one thermostat (mine has two separate thermostats). When one thermostat controls both, then I think it ensures that they do not try to start at the same time, which is how you can get away with 30 amps for two units. As stated, keep an eye on the voltage and make sure you do not run too much. Tripping the breaker is not a big deal, you can just reset it, but if the voltage drops too low bad things happen to the AC units.

Strador wrote: I have been working with the math and 30amps is enough to run 2 AC units once you get past that huge initial startup draw.That's one of those 'looks good on paper' things, but in reality you're likely to burn up your plug.

Two typical RV AC units draw enough current that by NEC it's not code allowed. Max draw from a "dedicated" device is limited to about 80% of max rated current. So on a 30A circuit your allowed 24A from dedicated devices. Max draw for many AC units is 13.5A or more so running two violates that. For that reason RV's with Two AC units on a 30A system come from the factory with a switch allowing one or the other AC unit to operate, but not both.Now there are some newer units that draw around 11A, so in theory you'd be OK, but not much else running. Next issue is starting current with one unit already running.Without easy start, you'd need the breaker to handle a short term 50A load or so. Not likely happen w/o the breaker trippingfor a DIY install on a 30A unit, the easy start would definetly help. On my install with easy start, max current draw on startup is down around 20A, so the question is, with one unit running and drawing 13A, could the breaker handle a 20A several second surge? Maybe, if nothing else was onOverall, IMHO NEC code requirements and common sense lead me to say I personally wouldn't try to run two AC units on a 30A system even with easy start. I'd convert the trailer to 50A. But then, many of the places we go are limited to 30A service, so I'd still be stuck, and when dry camping, same thing.I just turn the AC unit on when temps hit about 74 and let it run. It will keep my trailer comfortable. If I wait till temps are in the upper 70's inside, the AC can't bring the temp down, it's able to hold a temp but not bring it down in a reasonable time.

EasyStart type devices are great. Other options include selecting a lower BTU unit, or even wiring it separate from the rest of the RV so that it's on its own power plug.

Easystart functionality built into RV AC units?

2oldman
Explorer II
Jul 20, 2020
Strador wrote:
I have been working with the math and 30amps is enough to run 2 AC units once you get past that huge initial startup draw.
That's one of those 'looks good on paper' things, but in reality you're likely to burn up your plug.
Neil_Citro
Explorer
Jul 20, 2020
Strador wrote:
Pardon my greenness. I am 100% a newbie when it comes to RV’ing. I have a 33 ft class C, 30 amp, that has a single AC unit. The fan in the bedroom is pre-wired for a second unit, so it should be easy to install, I live in Arizona so the second unit would be nice to have.

Obviously, the issue is power, or more specifically startup power. I have been working with the math and 30amps is enough to run 2 AC units once you get past that huge initial startup draw. In doing some reading it would appear it should work just fine using products like easystart or softstart.

I guess my question is, why are RV AC manufactures not including easystart/software capabilities directly into the unit? Or, are there actually units out there that does this and I can’t find them? It would seem like this would be a no brainier especially with the RV power limitation?

I have a 50 amp fifth wheel so I think it is different, but my understanding in the 30 amp motorhomes is they run on one thermostat (mine has two separate thermostats). When one thermostat controls both, then I think it ensures that they do not try to start at the same time, which is how you can get away with 30 amps for two units. As stated, keep an eye on the voltage and make sure you do not run too much. Tripping the breaker is not a big deal, you can just reset it, but if the voltage drops too low bad things happen to the AC units.
valhalla360
Navigator
Jul 20, 2020
Because it costs money and generally they aren't needed. A 30 amp outlet is plenty to start a single air/con and a 50amp outlet is plenty to start 2 air/con units (or even 3 units).

It's really only when you try to use an undersized generator or overload a 30amp outlet, where these units really become useful.

Also running 2 air/con units is pretty marginal on a 30amp outlet. Keep in mind, 30amps is the nominal rating. Continuous output is limited to 80% or 24amps. You see a lot of burnt up 30amp plugs from people who think they have 30amps, so they are going to use 30 amps.

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