Lowest power 5K AC? (Both a question and a candidate)

[khigh]

Anyone else researched this? I've been searching things like "highest SEER 5000 BTU air conditioner" and "lowest wattage" and lowest startup amps" and that kind of thing, and it seems like I've hit the same air conditioner a whole bunch of times.

This isn't any kind of endorsement. I'm actually looking to see if anyone has seen better numbers on a 5K Window unit or either positive or negative experience with this one.

Frigidaire FRA054XT7 - http://www.frigidaire.com/Air-Condition ... FRA054XT7/

It pulls 4.5 amps/465 Watts and has something called "Low Voltage Start-Up", but what I can't find is what that exact number is. I'm not too concerned about running it - I'd just like to avoid a big generator surge in the middle of the night - even with an inverter generator. It's got a SEER of 10.7 which is only one of two I've seen in the double digits. I forgot the name of the other one, but it was like $500.

I wish I could find the specs on that low startup. That sounds intriguing.

I know the mini splits are more economical and I wouldn't be opposed to it, but I haven't seen one that small. Basically I've seen them around 9K pulling the same power as a 5K window unit, but the 5K is already overkill, so it doesn't really buy me anything if it's using the same amount of energy - I'd have to pay more and plumb it. I'd definitely look at going that route if I ever go 20 foot plus. Conversely if someone is aware of a 3-5K mini split, I'd love to see it assuming it trounces the window unit numbers. The 2.K external units formerly known as "Petcool" are shockingly inefficient, too - I was surprised - the one I looked at drew more than the above unit while giving half the cooling.

[OverTheTopCargoTrailer]

[khigh]

That's encouraging that both of us came up with the same unit presumably researching the exact same goals. My background is in engineering (as yours could be too) and you're an experienced builder, so that's bordering on a statistic.

I have no shortage of power (to run a 5K A/C by itself) using a Champion 2000/1700 inverter generator.

My goal is noise reduction. I've found that when regulations don't prohibit overnight use, fellow campers in a primitive setting don't mind a low level sound-managed drone - it's the kickdown that they hate, which I'm trying to avoid/minimize and why I'm so curious about the specifics of the "low power startup" Have you quantified those numbers with a meter of any kind?

Ultimately it would be nice to run it off an inverter, and my engineering math is a bit rusty, but it would take at least 4 batteries, which isn't in my initial building plan.

[norcal2]

For noise reduction you can build a sound box that you can set the gen in or on top or around that can can take apart break down and store..they are not to hard to put together if noise is your concern and soundmat is pretty cheap..just a thought.ive seen a lot of them around noise concern areas.

[khigh]

For noise reduction you can build a sound box that you can set the gen in or on top or around that can can take apart break down and store..they are not to hard to put together if noise is your concern and soundmat is pretty cheap..just a thought.ive seen a lot of them around noise concern areas.

I'm all over the noise reduction.

For one, I'm building a four sided (three sides and a top) enclosure out of 2" foam board I can erect on site with some sort of system of Velcro straps. I point the open side away from camp and leave that end open so I don't have any air/heat problems. Sound prefers to travel in a straight direction, so I point that end (with the exhaust)away from camp.

Secondly I put it at least 50 feet into the woods. Sound drops 6db for every doubling of distance. Since generators are rated at 23 feet, I double the distance there and lose 6db. That's with a 12GA cord. I may invest in a 10GA cord to double again from 50 to 100 and lose another 6. Now I'm at like 38db without the enclosure, even, plus except for startup I'm running at 1/4 capacity at night which is the idle speed.

Lastly, since it would only be an issue with primitive, I get as close to the treeline as possible and take it as far into the trees as possible (chained, of course). See #1 - any obstructions break up the sound.

I'm positive you won't even hear the generator over the AC itself. I'm looking forward to seeing what it sounds like even without the AC once I get the enclosure built. You can literally stand toe to toe over it and have a normal conversation, so it's not a huge challenge to begin with.

[Glenlivet]

I have the very inverter generator and a 5200 BTU window shaker, the specs of which I don't know. In steady cooling operation the A/C makes the generator operate in econo in the second step, but the initial startup surge is large enough that when the generator is in econ and cold and the A/C has not been run that day, the startup surge will most often stall the generator. However, once the generator is warmed up and the A/C has operated for 10 minutes then the A/C's cycling between fan only and fan with compressor barely makes the generator change cadence. If you make sure it's revved up on first startup (or is thoroughly warmed up) then if fellow campers don't mind the Champion inverter generator in its lower steps then they oughtn't mind it with that A/C running.

http://youtu.be/GTYvY162eyc

[OverTheTopCargoTrailer]

Ok looks like your all set

[khigh]

I have the very inverter generator and a 5200 BTU window shaker, the specs of which I don't know. In steady cooling operation the A/C makes the generator operate in econo in the second step, but the initial startup surge is large enough that when the generator is in econ and cold and the A/C has not been run that day, the startup surge will most often stall the generator. However, once the generator is warmed up and the A/C has operated for 10 minutes then the A/C's cycling between fan only and fan with compressor barely makes the generator change cadence. If you make sure it's revved up on first startup (or is thoroughly warmed up) then if fellow campers don't mind the Champion inverter generator in its lower steps then they oughtn't mind it with that A/C running.

http://youtu.be/GTYvY162eyc

Holy smokes, is that your video?

I kind of thought the math was there to run the AC and the microwave at the same time but dismissed it due to real world losses. I had just assumed I'd turn off the AC for the two minutes or whatever I microwaved something.

Good to see a good report on the Champion! Thanks for sharing.

[khigh]

As a mater of fact it did not start with my Magium 1000 PSW - rated 1700 max
Don't really know why not ?

There are the Running Load Amps and the surge amps you have to contend with for mains power and generator power, but there's a third figure called Locked Rotor Amps in air conditioning that comes into play with power inverters. It's a huge figure - one example I found was 28.2 amps, but it's so momentary ("a fraction of a second") that mains power and generators don't have time to react to it but that inverters, and possibly just some inverters (?) will crap themselves over it.

It kind of gets into mumbo jumbo at that point (or maybe before) - or smoke and mirrors, with the takeaway "You need a really big inverter, a lot of batteries, and huge cable".

[warnmar10]

...
, with the takeaway "You need a really big inverter, a lot of batteries, and huge cable".

Or a compressor start capacitor and PTCR.

About the most concise explanation of LRA I've seen:

The current drawn by an induction motor is a function of the rotor speed. The applied voltage creates a rotating magnetic field. When the rotor is rotating at the same speed as this magnetic field, the input current is minimum.

When the rotor is stopped, the input current is a maximum. This is because the turning rotor produces a back EMF that reduces the input current. If the rotor is not turning, there is no back EMF, and the input current is the highest. This is refered to as the "locked rotor current" because it is the same current that would be drawn if the rotor were locked in place so it can't turn.

When a motor is first started, the rotor is stopped, so it draws the locked rotor current. The motor quickly starts turning, and the rotor current decreases. The current keeps droping until the rotor gets up to full speed. At that point the current is at minimum. (Full speed is slightly less than the speed of the rotating magnetic field, and depends on how much torque the motor must produce to turn the load).

http://forums.mikeholt.com/showthread.p ... post560036

[khigh]

Or a compressor start capacitor and PTCR.

That's true, too.

That's a part of my initial questioning on this unit with the "low power starting" to see if it had a hard start capacitor built in, or if it could be added, added to, replaced, beefed up, etc.

I have a feeling it's probably a little bitty one.

I'm looking forward to getting the unit and hopefully not tearing it up before I use it.

[warnmar10]

That's true, too.

That's a part of my initial questioning on this unit with the "low power starting" to see if it had a hard start capacitor built in, or if it could be added, added to, replaced, beefed up, etc.

I have a feeling it's probably a little bitty one.

I'm looking forward to getting the unit and hopefully not tearing it up before I use it.

My only experience is with my EU2000i and either a 5,000 or 8,000 btu window a/c. The Honda runs either of them effortlessly. If you're using a modern a/c unit with electronic control, the control won't allow it to short cycle. That is, once the thermistor is satisfied and the compressor shuts off, the control won't allow the compressor to attempt a restart for several minutes. This allows time for the low side and high side pressures to approach equilibrium such that the compressor isn't trying to start against head pressure.

With correctly sized start components a compressor will start against full head pressure, at least when connected to utility power it will. With electronic controls AND a start circuit you should be golden in most any circumstance.

[khigh]

Oh I'm well beyond worried about running it. That's my same generator shown above powering a window unit and microwave at the same time.

I'm into a mix of theory and wondering what it would take to run it on an inverter now.

[abqlloyd]

Speaking from much experience, most people don't use large enough wire to take full advantage of their inverter's true rated capacity. They incorrectly assume it's the inverter. A 2000 watt inverter, especially a pure sine inverter, will power a small AC unit if it's properly wired.

In commercial RV's I've seen 8g wire running 12 feet to the battery box. The fuse is not the proper type and the wire is way undersized. All that happens is the fuse pops or the load won't run. The users then assume the inverter isn't enough.

[GuitarPhotog]

Few people are equipped to provide the 165+ Amps that an inverter that size requires at full load. Whether it be battery capacity, wire size, or circuit breaker size.

A/C units require considerably higher power when starting, because of motor startup requirements. It's not unusual for a 450W 5K air conditioning unit to require 8-12 A (1000-1450 W) at startup. Such requirements don't usually stall a generator, but can easily "bottom out" an inverter.

<Chas>