Visit our Popular Forums

richinny · 09-17-2008, 02:28 PM

ok, this post might give a trail tomore data.

http://www.airforums.com/forums/show...7&postcount=11

mistral blue · 09-17-2008, 02:35 PM

FWIW, I took delivery of a gently used Honda 3000 w/wheels last year for about $1G total. New low profile 15K Dometic AC this year. Big frig. No microwave. No electric coffee maker. No TV. No hair dryers. No furnace. No solar. Plenty of lights. Stereo runs constantly. Laptop. iPhone. AGMs.

The issues I have are the weight, the size and the fuel. I wish it was lighter, smaller and could run off of propane. But for the price I paid, I am VERY happy with this unit.

Hope this helps.

TinLoaf · 09-17-2008, 02:38 PM

I can only speak for myself here. My 13,500 btu DuoTherm Penguin heat pump takes 12.4 amps for the compressor and 3.5 amps for the fan motor totalling 15.9 amps of the 16.7 amps that the Yamaha 2400 is rated for. That leaves less than 1 amp of overhead which quickly disappears with elevation.

I assumed that a 15,000 btu unit would use more power, but the 15k Penguin heat pump takes 12.0 for the compressor and 3.3 for the fan totalling 15.3 amps - that's less than the 13,500 btu unit.

I think the key here is the surge at startup. It takes a lot of amps to get that compressor started and the Yamaha 2400 does the trick for me.

richinny · 09-17-2008, 03:02 PM

http://www.cumminsonan.com/www/pdf/rv/f-1362.pdf
note the comments next to the microwave on page 2!

http://www.powermate.com/generators/...ide_update.pdf

Honda Power Equipment - GENERATOR WATTAGE CALCULATOR

Generator Sizing Chart - Yamaha Motor Corporation, USA

How to Select a Generator for an RV - Wattage estimator

mustang · 09-17-2008, 03:13 PM

I found some info from 2 different A/C Installation manuels. I am not much on electricity so maybe this will shed some light on things.

It says the heat strip uses 12.7 amps or 1530 watts at 120 volts. This is on all units a BTU rateings

It says the 7100 and 11000 BTU units use 2.5 KW for A/C

It says 13500 to 15000 units use 3.5 KW for A/C

You would add the watts for heatstrip it looks like.

I am not sure of KW to convertion so feel free to give input I guess.

If I was better with my computer I would scan this page however, If it came with mine then we should all have the same Info.

It also says 12 AWG copper up to 24 ft and a 20 amp timedelay fuse or HACR Circuit Breaker

Fine print mentions High alltitude power loss and poor maint ect for generator.
Have at it guys

mustang · 09-17-2008, 03:18 PM

Those are some good links Richinny

I wonder how to convert KW to watts??

TinLoaf · 09-17-2008, 03:25 PM

1 kilowatt (KW) = 1,000 watts.

I think your manual is suggesting that you need 3,500 watts to cover the surge to get the compressor started. That's a bit on the high side. Once running it takes much less.

mustang · 09-17-2008, 03:31 PM

It seems to be a bit off from the generator companies say is required. I will try to scan this and post it. I have the same info from my old penguin unit as my new Duo Therm. I fried my penguin at a state park from low power. That is what the R/V dealer said.

I was lucky he had a used one that was to small for a trailer and had to upgrade so he gave me a deal on this 13500 unit

mustang · 09-17-2008, 04:07 PM

http://www.airforums.com/forums/atta...1&d=1221689195

I think I uploaded it. Yup well thats as good as I can get it. Hope this helps.

This is out of my DuoTherm 579 590 595 roof top A/C manual
Penguin is the same.

Wayne&Sam · 09-17-2008, 04:27 PM

I've had good luck with my Yamaha 2400. It runs the AC fine but you need to remember to set the refrigerator to LP not auto. On auto it will use 110 volts to run and that will overload the 2400.
Using lights and other 12v stuff won't bother it.

mustang · 09-17-2008, 07:03 PM

I am curious. Has anyone tried a volt meter (the 1 that plugs in to there socket) While the A/C is on. I guess you would know then. If it drops below 110 then your A/C will work but you will cook the compressor.

thecatsandi · 09-18-2008, 09:17 PM

Quote:

Originally Posted by mustang

I am curious. Has anyone tried a volt meter (the 1 that plugs in to there socket) While the A/C is on. I guess you would know then. If it drops below 110 then your A/C will work but you will cook the compressor.

Yes I have. At times it dropped out below 100. Probably what led to the early demise of my old unit.
I asked the tech what the spec are for my new on adn the looked it up an it is 106-130 volts. The last campground I was in the voltage did drop to 106. This one is holding well around 115-120. Even with everyone's AC running.

mustang · 09-19-2008, 07:51 AM

Well then there you have it. Low voltage is not a good thing, it is a compressor killer.

I called Dometic just to make sure and they reccomend a 20 amp time delay circuit for there units 13.5 to biggest.

utee94 · 09-19-2008, 08:08 AM

Still not sure why you'd see steady state voltage sag in a generator if it's running at its Rated capacity which has a good safety margin below Max capacity?

Facilities at a campground are definitely another matter.

flitzwhopper · 09-19-2008, 08:18 AM

I have a Honda 2000. Worth every penny. It will barely run the AC on the twink. I'll get a Honda 3000 when I can afford the change. For me, weighing a bit more is an asset. While a man can pick the 2000 up and run off with it - after cutting the chain off, that would more difficult with a 3000 secured in the bed of my TV. I don't usually remove the Honda 2000 from the bed of the TV so leaving a 3000 in the TV wouldn't be a problem. Getting it in and out with a ramp isn't a problem.

one man's opinion

mustang · 09-19-2008, 10:09 AM

Once again I think , and the figures show 4000 watt is pretty much the smallest gen set if you want to run anything else with your A/C unit. Including the heat strip. "It is what it is"

utee94 · 09-19-2008, 10:55 AM

I don't believe the heat strip and compressor run at the same time, so the power consumption should not be additive. It's an either/or situation. The fan will run in both cases.

I understand that there are people who say a 4K unit is the smallest you should go, just as there are people who say that you should not pull any Airstream over 16' with anything less than an F350 Diesel Dually.

But I just don't see it in the numbers.

If the concern is the steady state running voltage for the sake of your compressor's health, then a spike at startup should not affect that issue. So in other words, if for example a Yamaha 2400W system can withstand the startup spike in current/power consumption, then when it comes to steady state running power, the maximum that my 15K BTU A/C unit pulls down is spec'd at 1.6KW. This is comfortably below the rated wattage of 2KW for this compressor, and FAR below the peak supply power of 2.4KW. So if the compressor can withstand the startup event, then it should not endanger the compressor beyond that, even with some lights running. I would say that if you want to run a microwave and/or hair dryer, then you should either turn off the A/C or get a bigger generator. But everything I'm looking at is telling me that if a 2.4KW genny can withstand that peak current at A/C startup, then it should be able to power the A/C at a steady state without much trouble.

Unless of course these generators are experiencing voltage sag when running only at their rated power, which is well below the peak power. If that is true, then I could certainly see the potential to damage the compressor even when running at rated capacity. But also, if that is true, then I have to question the overall quality of the generator as well? I don't see any reason why a high-quality genset should experience voltage sag when running only at its rated power capability.

purman · 09-19-2008, 10:58 AM

wish I could get a generator that big but weight is an issue for me.... I don't have a separate truck to tow with... (and put it in) Well I do but it's a '75 dodge with a 440 which would be great but with 2 kids and a wife it won't work...

So the Honda 2000i is 20 lbs lighter than the Yamaha 2400 Is that extra 400 gonna make that big of a difference?????????? like i said I am not really looking to run my A/C just everything else and charge the batteries...

utee94 · 09-19-2008, 11:05 AM

Quote:

Originally Posted by purman

wish I could get a generator that big but weight is an issue for me.... I don't have a separate truck to tow with... (and put it in) Well I do but it's a '75 dodge with a 440 which would be great but with 2 kids and a wife it won't work...

So the Honda 2000i is 20 lbs lighter than the Yamaha 2400 Is that extra 400 gonna make that big of a difference?????????? like i said I am not really looking to run my A/C just everything else and charge the batteries...

I would think the 2000 would be fine for running your other systems and charging the battery, just not the A/C. And I believe others on this thread have said as much already if I was reading correctly.

The A/C is definitely the largest current draw in the whole trailer, by a large margin.

And I really do appreciate everyone's input-- I'm not trying to be obstinate, I really am looking for real-world experiences from people who can provide anecdotal evidence.

I think it's really easy for a manufacturer to state that you need to use a 4KW or 5KW genny in order to run their A/C. That gives them a HUGE error margin and absolves them from a lot of potential responsibility for their product.

But I'm looking for the real numbers, and right now, it just doesn't look like a 4KW or 5KW genny is really necessary. But I will readily admit that I am not a Power Engineer, so there could certainly be something I'm missing.

mustang · 09-19-2008, 12:29 PM

Heres real numbers.and facts.

"I Burned up my A/C Unit"

Cause = LOW voltage

I was lucky and found 1 cheap from a guy at the camper place. It came on a unit, and it was the wrong size.

I gave him $150.00 for it. I learned my leasson.

I only have real life experience on this issue. When you here people saying
"It barely runs my A/C BAD BAD

If a generator company says there unit 2000 watts will run an A/C get it in writeing and make sure they guarrentee it with replacment.

I bought a voltage meter and a circuit analizer, When I go to campgrounds I have them in a socket 24/7. If someone is running an old frige on your power line before the pole and the motor is putting voltage threw the ground, that can burn up circuit boards in any appliance that has them and is running.

I have nothing to prove, I got my gen set. I have a safe margin for error.

I posted requirements from 2 different A/C units, so it would be clear, My numbers where not grabbed out of the sky.

If you need only 500 or 1000 watts I reccomend an inverter. They are silent, Small, and can stay plugged in to ciggerette lighter. No oil to change or mix.

Good luck with your choice.