Running both roof A/C units

[On a Mission]

Only one ac runs on generator, if you are hooked up to 220 then both run, I was hooked up to shore power ac running put generator on and pop breakers, now AC only works on shore power,?

[dros_d]

Why not close the back off when you are travelling? I just shut the doors to the back.
the rear AC is not going to help the temp at the front of the coach much.
Your generator should be supplying power to both AC units.
Your gen should be putting out 220 volts, 110 volts on each leg of your power panel
Check your power panel for tripped breakers
Your transfer switch flips the power input from shore to gen.
sometimes they get fried and only one leg is engaged.
Now, not all coaches are set up the same way, and sometimes a prev owner will change things, so without seeing your coach...
My coach is a 05 Seabreeze with a 2000 watt inverter, best guess yours will be similar

[On a Mission]

So a mh can run two 10,000 btu on generator? I've been told only will ruin both when hooked up to 220 that's all the second wire is for? I'm going to test my generator Power maybe it's only putting out 120 I didn't know they put 220 out.
99 National rv 7372 Freightliner Trade Wind 300 HP Cat, I'm just learning my way around her.

[lkmaurice]

Thanks for everyone's input / suggestions. So far as I can determine at this moment is 1) the circuit breakers are fine and 2) as far as I can determine is there is a transfer switch ( noted in electrical diagrams in the gen set literature) yet I have had no luck determining where it is located. I doubt that there would any difference from a 2005 from my 2004 as to its location. Unless there added info I am going to the dealership seeking their solution. Thanks again everyone.

[On a Mission]

Dros,
Yep I have 220 coming from generator well 2 legs I'm at dixon lake no generator so I'm going to see if they are both hot, if so why is it not coming thru The transfer box to the coach beaker box. Only shore power comes to breaker box?



Help me get one ac to work on generator id be a grateful.
Can I just jump the wires straight to breaker box in coach?

[On a Mission]

Sorry for jumping on your post but Im just trying to get out fixed. Best luck to you..

[BFlinn181]

lkmaurice when you plug in to shore power you should hear the transfer switch click as it switches from generator (usually default) to shore power. You said the A/C didn't work on generator. Did you out wait the built in delay? There's a delay in the transfer switch to allow generator to get up to speed and stable. Then the A/C units will typically have a delay to allow fan to start before the compressor kicks in. Also the A/C delay allows pressure to equalize in the A/C if it had just been turned off before re-starting.

On a Mission, how big is your generator? If it is not sized to run both A/C at once, they often will have a feature to alternate A/C's to provide cooling front and back.

Remember Amps = Watts / Volts. Watts = Volts X Amps. You can look at the markings on your electrical items and do the math.

A 13,500 BTU A/C will use about 14/5 - 15 Amps. But on start up, it will briefly draw much more. That's also why inverters usually list two wattages, max and normal.

While it is technically correct to say that 50 amp service is 240 volts, you will seldom see an RV use that voltage unless it is a newer all electric coach. 50 amp RV wiring has 2 'legs' of 120 volt, 50 amp power, one common neutral for both legs, and a ground. A connection from either leg to neutral will give 120 v with 50 amp capacity. The only way to see 240 v is to connect the two legs together. Since the legs are in opposite phases, as the voltage goes up on one leg, it goes down on the other, thus never overloading the neutral with 240 volts. IF EVERYTHING IS WIRED AS IT SHOULD BE.

A 50 Amp service yields 12,000 watts of power (2 X 120 X 50) A 30 amp service only yields 3,600 watts (120 X 30)

[dros_d]

If you have 220 coming from your gen you need to check your power panel
it has 2 legs also. with your gen running, are you getting power on both legs?
usually.. a panel will look like
50/50 15 15 20 20 15 ...
with th 50/50 being the main breaker( its a double breaker)
after that, it flip flops from leg1 to leg 2
so above 15 on leg 1
next 15 breaker is leg 2
first 20 leg 1....
its easy to check, flip a breaker on each leg and see if an appliance on that breaker is working
try it on shore power first and take note, then with the gen, should get the same result
You have a 7.5 kw gen, each ac is on a 20 amp breaker, 20 X 110 = 2200 watts each
mine is a 5.5 kw gen and can run both ac units on gen so you should be fine, given simlar ac units
plus startup surge so dont fire up both ac´s at the same time
I am not aware of any way to trick your ac´s into nowing the diff between shore power and gen so.. but I haven´t seen every rv out there either

[On a Mission]

120 all beakers work so the ac comes on. the generator 120 comes to the box that metal box does not click into place so no 120 thou it so nothing 120 works. I only have one hot wire the red one the black nothing.

[Mr_D]

Originally Posted by dros_d

If you have 220 coming from your gen you need to check your power panel
it has 2 legs also. with your gen running, are you getting power on both legs?

Very few generators will output 240 volts. Usually it's like our 8KW unit which has two 30 amp breakers and output is 120 volts on each leg.

[On a Mission]

Ok sun up I'll check that 30 amp breaker, you know what I'll go do it now kids sleeping it's cool out thank you everyone every post has helped me God Bless.

[SteveInPEI]

Originally Posted by BFlinn181

....
Remember Amps = Watts / Volts. Watts = Volts X Amps. You can look at the markings on your electrical items and do the math.

A 13,500 BTU A/C will use about 14/5 - 15 Amps. But on start up, it will briefly draw much more. That's also why inverters usually list two wattages, max and normal.
...
A 50 Amp service yields 12,000 watts of power (2 X 120 X 50) A 30 amp service only yields 3,600 watts (120 X 30)

1,000 BTU/hr = 0.293 kw
10,000 BTU/hr = 2.93 kw

@120v x 24 amps = 2.93 kw

For one A/C Unit .... IF it was putting out full load ..... But

http://home.howstuffworks.com/ac5.htm
"The energy efficiency rating (EER) of an air conditioner is its Btu rating over its wattage. As an example, if a 10,000-Btu air conditioner consumes 1,200 watts, its EER is 8.3 (10,000 Btu/1,200 watts). Obviously, you would like the EER to be as high as possible, but normally a higher EER is accompanied by a higher price."

And ...

http://www.busconversions.com/bbs/in...?topic=20751.0. :
"A typical 13000 btu AC will draw 18 to 20 amps starting, and around 12 amps running on 120 VAC. That is 2160 - 2400 watts starting, and 1440 watts running. Assume no more than 85% efficiency (inverter loss and MSW incompatability), so you would be drawing call it 1700 watts whenever the AC is on, or 142 amps at nominal 12 volts. Assume no more than 50% state of charge draw-down on your batteries, 24 hours of use would require 6,816 amp hours of rated battery capacity. That's around 27 typical 8D batteries. At 150 lbs per battery that's two tons of batteries. There is a reason no one runs air conditioners from batteries..."

This page says

http://www.hayesequipment.com/honda_...tage_guide.htm :

"Motorhome 5th Wheel and Camp Trailer Roof Top Air Conditioners
Watts Required for start up. &. Average wattage once running
7000 btu rv air conditioner 1700 600
10,000 btu rv air conditioner 2000 700
13,500 btu rv air conditioner 2750 1250
15,000 btu rv air conditioner 3500 1500"

(1,000 w = 1kw )

So ... That would suggest for 10,000 btuh unit -- 2000w/2930w = 68% of max draw on startup and EER = 10,000/700 = 14.3

If you are blowing breakers ....one suggestion is to start up one AC unit and then the other in about 10-15 minutes. ( turn off stat on one first )
That way the startup surge power draw is levelled off on the one ( 2000w ---> 700w ). And the gen can handle the other startup .... Maybe

Good luck !

[SteveInPEI]

Update search ...

ONAN gas generators Specs : http://www.cumminsonan.com/rv/products/gasoline
ONAN diesel generators Specs : http://www.cumminsonan.com/rv/products/diesel
Only the two largest diesel gens put out 240 V it seems.
See this link for all unit specs ... Some historic :
Recreational Vehicle Generator Set Specification Sheets and Service Diagrams. : http://www.cumminsonan.com/rv/support/literature/

GENERAC Specs : PDF : http://www.generac.com/Brochures/0179570SBY.pdf
Says 5.5 kw and up have 240 V output. (Or 120V) ..... Quiet pact and prime pact models.
Both gas and diesel.
See more here on each model ...links to diesel. ... http://www.generac.com/RV/Gasoline/Gasoline/

THESE ARE NEW UNITS.

YMMV

Cheers
sd

[On a Mission]

Realy a fuse switch, working with a 2 &4 year old just can't think right, I'm glad I opened & got into look 2 switches & one blown it was the leg running front ac, thank you for helping.