Generators and air conditioning

We have to possibility of Tropical Storm Ernesto paying us a visit in the next week or so. Due to medical reasons, my wife doesn't function real well without air conditioning. Being that it's August in Houston and we're looking at a heat index of 100+ degrees most days, we really don't want to be without the lovely cooling breezes of an air conditioner if there is a power outage due to the storm damage. I'm considering investing in a portable gas-powered generator to run a small window unit air conditioner to keep one room cool for my wife.

I'm familiar with the concept of the power requirements and the extra surge voltage needed when the compressor kicks on, but I was wondering if anyone here has run a window unit off a generator and what their experiences were. Thanks!

It is certainly possible to work a window A/C unit from a generator, but you will need a relatively large generator.

Determine the power requirements of the A/C unit, should be on the data plate or in the instruction book.
You will need a generator of least twice this power.

If the A/C unit uses 1KW which is about the smallest likely size then you need at least a 2KW generator.

If the A/C unit uses 3KW which is about the largest you will get in a window type, then you need at least a 6KW generator, which is about the biggest that is considered to be portable.

Dont forget a battery operated fan as backup, not to be compared with proper air conditioning but better than nothing if the generator or the air conditioner breaks.

If money permits consider a spare generator in case of failure.
A spare A/C unit might be worth considering but is arguably less important.
After a bad storm you should be able to buy an A/C unit if needed, but generators are likely to be sold out.

there is a neat electronic meter called a "Kill A Watt" by Intratec that can directly read volts, amps, watts, frequency and kWh.. to determine your actual current uasge

if you have natural gas available, I would suggest a conversion unit from someone like US Carburetion to save on gasoline cost

the research I've been doing on the inverter generators places the Honda EU2000i at the top of the list... the advantages are better fuel efficiency as they don't have to run at maximum rpm on standby, low weight, low noise, but they are pricey...from about $900 delivered on the internet...but they seem to be highly recommended by those with medical conditions

many of the lower end units have engines powered by known manufacturers... Honda, Yamaha etc, and generator heads from China, not that it is a bad thing..

the last modification I made to the ceiling fan thread works very well for a backup

Prepare your site carefully. You need to run the generator outside and away from structures and combustibles, with the exhaust not coming towards your house and particularly not towards the air conditioner. Portable generators shouldn't be run in the rain, so if you don't have a car port or similar way to keep rain off without containing the exhaust, consider putting up a canopy where you want to run the generator.

Use an appropriately rated (heavy) extension cord to get the power to the load. Use the shortest extension cord that will work for your application.

Along with the battery-powered fan, consider filling a large cooler with ice. A fan, a cold drink, and an ice pack on the forehead and the back of the neck can work wonders.

For the same investment, you could move over to a motel 6 ( some distance away) for the duration.

Got a Honda EU2000 I,seems to be a fine machine.

Have a Honda 3K inverter and it runs two 5K btu window units, fridge, and chest freezer without any problems.

I've run a 5000 BTU AC off my Kipor 2000W inverter-based generator set for full power. But the generator would occasionally trip-out trying to start a 6500 BTU AC.

There's a video on Youtube of a guy starting and running a 5000BTU AC off a 900W Harbor Freight generator, but I have strong concerns about the reliability of that setup.

Rule of thumb is that an air conditioner draws 2.5X the power during start-up as when running. I calculate 3X to allow a safety margin. Meters are not always a reliable indicator of surge power requirements because they don't update the display fast enough and don't have a peak load function.

As for emissions, always run the generator outside with the exhaust facing away from the house. Keep windows, doors and vents (including the fresh air intake on your AC) closed in the close vicinity of the generator. Putting the generator on the opposite side of the house from your AC unit is not necessary, and in hot weather you're more likely to want those windows in other parts of the house open for breezes.

I agree with the power and safety concerns of the above entries. I have a 5000 watt Coleman and it has worked great.

The lube oil needs to be changed about every 30hrs but check your owner's manual for the manufacturer's recommendations.

I usually get 8 hrs of power from each 5 gallon tank of gas. I also use StaBil in my stored gasoline.

I use synthetic oil in mine

Thanks for the info everybody. We dodged the bullet this time but next time I'll have some insight.

One more note about air conditioning. This was recommended once and it works for me.

Get an air conditioner that is actually a little too small for the room to be cooled. That will let the temperature rise a bit, but the unit will be running more nearly continuosly, which will dehumidify better. 78 degrees and drier is more comfortable than 70 degrees and humid. YMMV.

Depending on the humidity where you live, a swamp cooler might be an alternate solution. They work great here in arrid Colorado. But since you mentioned "tropical storm", something tells me that "arrid" does not describe your location! Swamp coolers are cheaper than air conditioning, need much less power, but really crank the humidy up as they cool you. I would not use one through the air conditioning/heating ductwork in my house because of the mold possibilities. But a standalone portable one, for emergency use, sure!

Anything can cool "UP TO" 500 square feet. Including the fan I made by folding up a sheet of paper. It's more likely that my little hand fan will only cool 0.5 square feet, but by definition, that is still "up to" 500 square feet! Marketing ploy from the A/C manufacturers, that's all.

i have two window units that only use about 500 watts each. no problem running both at the same time on my little honda EU2000i gen, but instead i run them on a small solar system (1000 watts of PV panels fed into 12V DC L16 batteries, then converted to 120V AC via invertor). each is enough to make an average size room livable in extreme heat.

How much space do 1000 watts of panels require? I know nothing about solar, but this sounds intriguing.

4 panels of {250 watts each} weighs total combined 200 lbs,would be 160 inches by 66 inches of space

http://www.solarworld-usa.com/system-designers/~/media/Global/PDFs/datasheets/sunmodule-solar-panel-250-mono-ds.pdf

thnx IzzyJG99. been using this system for years to run the house. rarely is the back-up generator needed. while it takes careful consideration to what electrical items you can use and for how long, we have everything we need, including laptops, modems, printers, satellite 'net and tv, a 52" flatscreen sony, full size stereo, power tools, et al...

spuds is correct. today it would only take four 250w panels and slightly less space than ours.

i have eight 120W panels that take up 8x8 square feet on the mount. here's a pix:

Thanks for that. Puts it into perspective.

BTW, you live in a most awesome place! I am so jeolous!!!

I tell ya,panels are major BEAUTIFUL IMO.

These are classics,real beauties in person.

Picked up a pile of these recently,somewhere around 1000 watts....with the federal tax credit came in at 83 cents/watt.

Be aware that MOST modern PV installations are grid tied and contary to popular belief do NOT give any protection whatsoever against power cuts.

What is needed is a system like that described above, in which the PV modules charge batteries, that via an inverter are used to power A/C or other loads.