Community Forums

TAZ · 04-02-2012, 09:52 PM

Has anyone tried one of these to run two AC unitson one 30 amp circiut?

http://www.parallaxpower.com/ALS%2020/ALS%2020.pdf

I am not sure if the shed load would ever run the second ac or if only one would run at a time.

LVJ58 · 04-02-2012, 11:22 PM

Our coach has 2 Dometic BriskAir units and we've run both on 30amps. When both are running, we shut off our electric power to water heater, coffee maker and don't use microwave. However we leave refrigerator running on AC.

You can probably check the specifications of the type you have to find out what the start and run amperage draw is and that will give you a better idea as to whether you can run both safely on 30amps without tripping a circuit breaker.

Good luck

jlfbatonrg · 04-02-2012, 11:26 PM

We run our 2 Colemans on 30 amps whenever we have to. together on full cooling they draw 23 amps.

Jim

Mr_D · 04-03-2012, 12:11 AM

We regularly run our two Penguin heat pumps on 30 amps with out much problem, that is till your wife tries to run the microwave at the same time!

TAZ · 04-03-2012, 05:25 AM

I was thinking about adding a hard star capacitor to each unit to lessen the startup load. My fear is tripping thenbreaker if the both start at the same time. I don't want to come back from a walk to find our lab in 100+deg coach

Thanks for the input.

sc3283 · 04-03-2012, 06:41 AM

Both my 13.5k Dometics run fine on 30 amp service. Each pulls just under 12 amps when comp on/fan high speed

Gary RVRoamer · 04-03-2012, 06:43 AM

You may already have hard start capacitors in the a/c - many, if not most, of them do.

Do you have an energy mgmt system (EMS) that will shed loads if over 30A? They work quite well and rarely ever let a breaker trip.

However, odds are the EMS will prevent the 2nd a/c from starting its compressor much of the time, so only the fans will run until the 1st cycles its compressor off. The compressor start load tends to push the total amperage over 30 long enough to trigger the load shedding. On my coach, the 2nd a/c will get its compressor running only about 1 of 4 tries, but if it does, they run fine together at a total of about 27 amps. To do that, I have to set fridge and water heater to propane mode.

Wizard · 04-03-2012, 06:43 AM

Not sure about your coach but on our previous Winnebago Brave, it had 2 different size AC units, the rear was smaller so it would draw less amps and could run both on 30 amps. We also would turn off the water heater and not use the microwave although the EMS would turn off on unit if I did turn on one of those.

clyon51 · 04-03-2012, 08:02 AM

Taz, that device seems to do, in part, what my EMS does. Don't see any reason it wouldn't work for your app.

Like I and others do to run both ACs, we do need to reduce other loads to keep both ACs running.

What appeals more to me, even with EMS, is to tap into the 20A circuit from the gennie (which generally only feeds the rear AC). You run a 20A cord to the pedistal along with your 30A. Now you have a full 30A for the coach, and a dedicated 20A for the rear AC.

wa8yxm · 04-03-2012, 09:15 AM

From the manual the ALS 20 will let one or the other run off a 20 amp branch but never both.. A true EMS system that also monitors the water heater, refrigerator, microwave and such and sheds loads as needed, ,, Would be a much better choice,

Generally.. I find Parallex products...lacking in ability, this one is no exception.

Now, that said.. I have, on 2 occasions (Well 2 locaitons) ran both A/C's on one 30 amp. NOTHING else, (Well the converter and some small electronics) my two Carrier V's (origial motors) drew 27 amps, the exact limit for a 30 amp breaker.

I have since replaced one blower motor.. I am not sure but I think it might draw just a touch less power. (perhaps 26.5 amps for the pair)

I do not have an EMS though. I do that myself.

TAZ · 04-03-2012, 08:18 PM

Thanks everyone. I do not have an ems and i am thinking abiut a second 20 amp line. A couple of my favorite campgrounds have the 20 amp on a common circiut with the 30 amp. Just an extra breaker off the 30 amp feed. So I am looking on how to run off of 30 amps max. I dont fave a read ac but the rig is wired and plummed for a second ducted unit. With the big windshield poinred south in the summer it does cook. The one unit struggles.

This summer I plan to add the second unit as well as electric heat element for the fall.