Adding a 3rd AC Unit

[JCat]

I have 2 AC's on my RV currently and I spend a lot of time in the Southwest where it can get to 110 120. 2 AC's won't cut it so I have decided to add a 3rd unit.

I welcome your experience and comments on my plan.

I will mount the 3rd unit where my kitchen vent is located.
Run a wire to my current thermostat for control
Run AC power from the unit to the rear of my RV, in the closet area where my washing machine used to be. I will add a breaker in line, and connect to the 120v outlet in the closet.

I will also run another AC line from that closet out to my electrical bay, so I can connect the 3rd unit directly to a 30 Amp shore power seperate from the rest of the RV, which would be connected to the 50 amp service.

I hope to accomplish the following:
When going down the road with the genny on I can run both front AC units and the 3rd will be plugged into the washer circuit.

When parked I can run all 3 units with the 3rd unit plugged into 30 amp at the pedestal and the rest of the RV to the 50 amp. This way I won't overload the RV's electrical system.

In the end I will have 3 15000 BTU Dometic units that I can run off shore power, and 2 15,000 btu units i cn run off genny power (7500 w Onan).

Have I thought of everything ?

[JCat]

You are correct tropical.

The cord will connect to a 20 amp breaker before it connects to the 30a power at the pedestal.

[tropical36]

JCat wrote:
Update: Had the AC guy out and talked to Customer Service at Mandalay.
The washer wiring gauge will not handle the AC as it is a 15a circuit.
The EMS in the RV will not be able to balance the load and would require an upgrade (per Mandalay) even if I add a 20A breaker and circuit.

I will add the AC, and run a wire on the roof down to a 20A breaker box and then a cord to the 30A pedestal connection.

So I will have the AC working only when parked.

I doubt very seriously if a running A/C draws close to 15amps and the starting current won't hurt or trip the breaker with it's built in power curve. As for your EMS, what does it know except for when you exceed the set current draw and it will then shed whatever loads you tell it to. I have mine to shed the air and only the air. In addition, I've installed a dual power adapter for the rear air, that I can unplug and re-plug into a separate outlet on the pedestal, so you could do that and wire your third one straight in to the breaker box if you can get to it and many have run extra AC wires inside the AC vents. They stay nice and cool in there, as well. Whatever you might do, be sure and put some breaker or fuse protection out front somewhere, unless you're going to use a min. of #12awg and will only be plugging into a 20amp outlet on the pedestal. You could even make yourself up a portable breaker box when plugging into any outside source, where you're not fully protected downrange and for the size wire that you're using.

[JCat]

Update: Had the AC guy out and talked to Customer Service at Mandalay.
The washer wiring gauge will not handle the AC as it is a 15a circuit.
The EMS in the RV will not be able to balance the load and would require an upgrade (per Mandalay) even if I add a 20A breaker and circuit.

I will add the AC, and run a wire on the roof down to a 20A breaker box and then a cord to the 30A pedestal connection.

So I will have the AC working only when parked.

[holstein13]

Executive wrote:
I run all three of my 15,000 Units off 50amps with no problems. You should be able to also. IMO, you're over thinking this. Keep it simple and enjoy your coach..Dennis

I agree. I also run all three of my 15,000 units off of 50 amps with no problems. Of course I used to trip the breaker when the A/Cs were running and I added the washer, dryer and dishwasher on top of the electric water heater elements and the battery charger. Then the wife would cook dinner on our induction range.

Since then, I adjusted the power management software to shed certain loads in case I go over 40 amps.

If you don't have a load management system, maybe the separate breaker is a good idea.

[Executive45]

I run all three of my 15,000 Units off 50amps with no problems. You should be able to also. IMO, you're over thinking this. Keep it simple and enjoy your coach..Dennis

[Busskipper]

JCat wrote:
I have 2 AC's on my RV currently and I spend a lot of time in the Southwest where it can get to 110 120. 2 AC's won't cut it so I have decided to add a 3rd unit.

I welcome your experience and comments on my plan.

I will mount the 3rd unit where my kitchen vent is located.
Run a wire to my current thermostat for control
Run AC power from the unit to the rear of my RV, in the closet area where my washing machine used to be. I will add a breaker in line, and connect to the 120v outlet in the closet.

I will also run another AC line from that closet out to my electrical bay, so I can connect the 3rd unit directly to a 30 Amp shore power seperate from the rest of the RV, which would be connected to the 50 amp service.

I hope to accomplish the following:
When going down the road with the genny on I can run both front AC units and the 3rd will be plugged into the washer circuit.

When parked I can run all 3 units with the 3rd unit plugged into 30 amp at the pedestal and the rest of the RV to the 50 amp. This way I won't overload the RV's electrical system.

In the end I will have 3 15000 BTU Dometic units that I can run off shore power, and 2 15,000 btu units i cn run off genny power (7500 w Onan).

Have I thought of everything ?

Just a thought -- Have you looked at an LG Mini Split System? Depending on size and location this might be an interesting option.

Just a thought.

BOL,

[tropical36]

holstein13 wrote:
I like the idea of the separate 30 amp plug for when you are parked. You are far less likely to trip the breaker that way. I did a similar install with my old gasser and it worked out great. I agree that you don't need 30 amps however. 20 amps would work fine.

That's fine, but did you in fact run #10awg (30amp) wire or maybe something smaller like #12awg (20amp) or #14 (15amp) wire.
If not the #10 and considering the enclosed run to the A/C unit, I would most certainly be using a breaker of the proper value and you shouldn't be having any tripping problems, anyway.

[holstein13]

I like the idea of the separate 30 amp plug for when you are parked. You are far less likely to trip the breaker that way. I did a similar install with my old gasser and it worked out great. I agree that you don't need 30 amps however. 20 amps would work fine.

[John_S_]

I can run my fridge and three AC units on with just my 50 amo shore cord. If you wanted to put a second line in to be able to run two ACs on 30 amps that is different but I have never tripped the pedestal except at Disney and that was just the charger alone. The pedestal was bad.

[tropical36]

lunch surfer wrote:
I did a similar install in my kitchen vent opening. instead of tying into exist thermostat I bought a self contained 15k btu Coleman AC with heat pump. I hard wired it to back and in electrical bay I installed a 30amp breaker and box with plug to run to camp ground pedestal. Only thing I cannot do is run it while on road but have not needed it yet. The 3rd AC is a great adder It has reduced our heater use and keep us cool in the hot Texas summers.

ctc

I just gotta ask as to the why of the 30amp breaker and if you indeed used #10awg wiring for this? Because if anything smaller, like #12 maybe, then this wiring isn't properly protected. Even if you used the #10 for possible voltage drops or for whatever other reason, you should have still used a 20amp breaker.

[67Cutlass]

JCat wrote:
Good feedback.
The reason I wanted to add a seperate line to connect the 3rd AC unit to a 30 amp when parked using shorepower, is because I did not want to overload the coach circuits.
Last year I had 2 roof ac's and 1 portable ac running, along with fridge, and other items,(no hairdryer or oven, just normal stuff) and the

50 amp protection box

tripped and shut off all power to the RV.
So I think I was drawing to many amps and it shut down.
With the 3rd AC going to the 30 amp connection I remove the amps this unit draws through the coach circuits.

Make sense ?

:h
As usual I'm confuse. Are you referring to the 50 amp outlet on the outside power pedestal or do you have some type of EMS?

If you have an EMS it could have shut down because of a low voltage condition which is very common at parks durning summer months. Also if you power your third AC off of the pedestal you would not have it protected and could easily damage it from low voltage.

Your 50 amp circuit should handle all three ACs without problems. I've only encountered one problem when using all three of our ACs running. We had the clothes dryer on, TV on, surround sound on and convection oven on at the same time without issue. Then my wife plugged in her curling iron. Our progressive EMS shutdown everything because of low voltage.

If you don't have an EMS I highly suggest you get one.

[dougrainer]

Remember, 50 amp service IS 100 AMPS of service. Each 15k at 100 degrees ambient will draw 15 to 16 amps each. We sold Mandalay(Texas where it gets 100 to 105), and 2 15k AC units should cool your RV with no problem. IF you are going into temps above 105, then the 3rd unit will do great. The Genset is rated at 63 amps total draw. IF you have the Intellitec EMS system, that 63 amps will kick out the EMS parameters if you go over that 63 amps when the Genset is running. The Intellitec KNOWS what the Genset amp supply is. Have you had your existing AC's checked for correct output? Doug

[Rick_Jay]

JCat,

Yes, it makes sense. I guess. But on a 50A connection I would think you should easily be able to run 2 ACs, microwave, water heater, refrigerator, etc. without tripping the breaker. Perhaps that pedestal had a "weak" breaker. Or, perhaps the park had "low voltage" and the AC units were drawing more current than normal to compensate. Remember that a properly operating "50A" connection can supply 50 amp on EACH leg, for a total of up to 100 amps.

We've never had a problem in our rig and I would think that a third AC should be no problem, as long as the loads are properly balanced in your breaker panel.

That said, it certainly doesn't hurt to have the separate shore power cord, as it might be able to help in situations such as you encountered.

Good Luck,

~Rick

[JCat]

Good feedback.
The reason I wanted to add a seperate line to connect the 3rd AC unit to a 30 amp when parked using shorepower, is because I did not want to overload the coach circuits.
Last year I had 2 roof ac's and 1 portable ac running, along with fridge, and other items,(no hairdryer or oven, just normal stuff) and the 50 amp protection box tripped and shut off all power to the RV.
So I think I was drawing to many amps and it shut down.
With the 3rd AC going to the 30 amp connection I remove the amps this unit draws through the coach circuits.

Make sense ?