Running two AC's at a time.

[Old-Biscuit]

Originally Posted by HelG

Actually, no, I didn't ask. At that time, I was just happy to get out power system going again. On our first trip, we had complete power failure. The generator ran, but produced no power.
We had to have a mobile RV technician come in to fix it. The transfer switch was the culprit, the wires got disconnected. The breaker of the inverter was tripped (no idea how that came about!). Meanwhile he searched for the source of the complete breakdown, he mentioned that "bad wiring" to me. He was in a hurry as he had squeazed us into his schedule to help us out.

Only the 15k BTU unit is controlled by a Domenic thermostat, the second unit needs to be handled directly at the unit. Both have their own circuit breaker with only the Domenic controlled unit installed at the fuse/breaker box. The other has its fuse right at the unit.


I am not under the impression that those rigs have a power management built in from the get-go unless they have two ACs factory installed. Reading through your comments, I am inclined to have it installed. Not sure I trust my abilities enough to do it myself.

Originally Posted by Onyrlef

So if the breaker to the second a/c is at the unit , from where is it getting 120v? Sounds suspiciously to me it may be tied directly into the #10 shore power line, skirting the dist. panel . Were it run to the dist. panel, why would the breaker be at the unit?

HENCE the 'BAD WIRING' comment for RV Tec??


Need to find where the bedroom A/C Unit with CB at the unit is getting the 120VAC Power from????
Circuit Breaker for that A/C Unit should be AT the SOURCE, not at the UNIT
*CBs protect wiring NOT appliances

[MarCec]

Originally Posted by Onyrlef

Unfortunately, without running everything through a pms it's not going to happen on a 30 amp system. Magical thinking notwithstanding. Those in 30 amp rigs with the 2 a/c's and the pms with whom I've spoken all tell me they work flawlessly.

Until they don’t. We had a 99 Winnebago with two ACs that ran flawlessly for years. We were second owners, buying it in 2001. We kept it in top condition, fixing every issue immediately. Then one trip we ran them off the generator on the road but when we turned them off for refueling they wouldn’t restart. As it turned out the inverter or something was fried.

The previous owners wanted to run the AC from 30 amp and rewired it to by-pass the safety mechanism. Sorry… my husband isn’t here to help me explain in formal terms. Over the years we had replaced a couple of outlets that shorted out. We found out that it was just a matter of time before the motorhome could have caught on fire. We could rewire it for 30 amp or pay a little more to upgrade to 50. We opted for 50.

The safety mechanism factory installed would only allow running one while using shore power. You could use both when running the generator. Since we mostly travelled in the Pacific Northwest we were not continually using ACs while on shore power. For us it was a slow process of frying the wiring. Had we lived and traveled in hotter climates we probably would have had a fire.

If anyone plans on running both ACs on 30 amp shore power I would recommend making sure it was actually designed and wired for it. We could have burnt to the ground because someone removed a safety device.

[azlandman]

I installed softstarts in both of my original A/C units (99 National RV Tradewinds) and all works well on 30 amp.

[maybe I care]

Is it not possible to run the new softstartup . It could save you moola bypassing
a RV electrician and all but it's more then just a softstartup. It's not cheap but what is now days.

https://softstartup.com/rvlife/?utm_...-Smarts-Review

[ipgenie]

This won't apply to many others but I figured I'd post it as an option.

A few years ago I installed a Magnum Hybrid inverter, solar and lithium batteries in our 5th wheel. I also put soft starts on both air conditioners. To finish it off, I installed a load shedding switch on the electric water heater and microwave, giving the microwave permanent priority if both devices were on.

A couple of months ago we went to our annual week long swim camp with the kids. The site we had reserved had a shelter and 30A power. However, the breaker in the pedestal was broken and would not energize the outlet. They would not have an electrician available that week. We could have moved spots, but would have lost the use of the shelter so I turned the grid source down to 16 amps on the Magnum and plugged into the 20 amp outlet.

We ran both air conditioners, electric water heater, microwave, electric fireplace, crock pot, electric fridge, etc. just like we would have if connected to 50 amp power. Anytime the load was higher than 16 amps, the Magnum would draw the remaining load from the batteries and when it dropped below 16 amps, it would use the difference to charge the batteries back up. The 2kW solar array also charged the batteries through the day, carrying a good part of the load.

I watched things pretty close the first couple of days and the battery bank never dropped below 80% and was always topped up each morning by the time it got hot enough to switch on the air conditioners. AC voltage stayed in the low 120s and I was the only one who even knew that anything was out of the norm.

We dry camp most of the time and often run both ACs on our little Honda 2200 in combination with the Solar/Magnum/Lithium combo for a few hours during hot days. Unless we need AC we don't need the genny, we have more than enough solar and battery for our wants.

This is not something that really applies to the OP or to most RVs but I've been very happy with this system and it was a fun project to design and install. It's been running without issue for the past 7 years and when it comes time to move to the next RV I'll be doing something like this again.

[BoJango]

We owned a 1996 Winnebago at one time. We could only run one AC at a time on shore power. It was our choice as to which. Both AC units would run fine on the generator. However, I had the voltage regulator on the generator to burn out. This happened two times. It was very hot in Calvary, Georgia and the two ACs were running constantly. We no longer have a problem running two ACs in our Holiday Rambler Ambassador which is 50 amps.

[TomsBusyBees]

You could consider changing out your 30 amp service to a 50 amp service. then run the A/C's on separate legs. If you a generator, then you would also need to change out the ATS to a 50 amp. Instead of 10 gauge wire from shore power, you need to run 6/3 with ground. I just did mine, a 2017 SunSeeker 32' class c. An RV shop will cost you high dollars to do this, but if you know enough electrical, it's not a hard job. I spent right at $400 dollars for all the parts to change it from 30 to 50. The highest cost was my ATS, which was $200 from Amazon. Good luck!

[Tilted Kilt]

A 30-amp coach has 3,600 watts available. Check the wattage on the A/C labels. If you start each unit separately to avoid high inrush current, you should be fine if the combined wattage is less than 3600. What I have observed at campgrounds is that people will run and extension cord from the 120 Volt receptacle into the RV for other electrical needs while running their A/C units. It's all about knowing your loads and balancing them.

[NXR]

Coachmen offers for this particular unit two options: Either one 15k BTU AC or two 11k BTU ACs with power management.

You can install a soft start device on each roof unit and perform the power management manually. I installed two Micro-Air EasyStart soft start units on our two 15K roof units and I can easily run both at the same time on a 30 amp pedestal.

But we do shut one down when using the microwave or a coffee brewer and we switch the water heater from electric to propane. An electric water heater consumes more than 1/3rd of a 30 amp pedestal when it's actually heating water. We are able to keep the Norcold 1210 (450 watts) on electric, though.

Ray

[Johndale]

Originally Posted by NXR

You can install a soft start device on each roof unit and perform the power management manually. I installed two Micro-Air EasyStart soft start units on our two 15K roof units and I can easily run both at the same time on a 30 amp pedestal.



But we do shut one down when using the microwave or a coffee brewer and we switch the water heater from electric to propane. An electric water heater consumes more than 1/3rd of a 30 amp pedestal when it's actually heating water. We are able to keep the Norcold 1210 (450 watts) on electric, though.



Ray

I installed micro air soft start and there soft touch thermostat and yes you can run both ACs on your cord I have and no issues. Plus I made my inputs now to 60 amps since I have a Onan 5500 generator. I just added another 30 amp auto transfer switch and works great. I am bringing my old girl to 2023 upgrades. I am almost done with her and will post more on a new thread.

[firstaidman]

Originally Posted by azlandman

I installed softstarts in both of my original A/C units (99 National RV Tradewinds) and all works well on 30 amp.

Were able to run both at the same time on shore power before installing the Softstarts? I can only run both of mine at the same time on generator. I don't have softsarts.

[firstaidman]

Originally Posted by azlandman

I installed softstarts in both of my original A/C units (99 National RV Tradewinds) and all works well on 30 amp.

Were you able to run both at the same time on shore power before installing the Softstarts? I can only run both of mine at the same time on generator. I don't have softsarts on my 1988 Dolphin.

[Florida Rang]

You could wire the non factory a/c unit on a separate shore power cord . Then use it when you have shore power and not have to worry as much about using other appliances in the Motorhome. My friend does this and it works very good. On shore power he use the 20 amp receptacle on the the shore pedestal…