It seems like a good metric when it’s just an academic discussion; but once she hears what a portable generator actually sounds like (i.e., you can’t sleep inside the house while it’s running), the metric will promptly change to noise.
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Honda may be considered the best, but they don’t have an exclusive lock on quiet inverter generators.
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Agree. I wasn’t endorsing Honda - only pointing out that the metric may change from cost to noise.
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Propane will provide more power than natural gas but not as much as gasoline. Compared to gasoline you’ll get 80-85% of the rated power where as natural gas will be 70-75% of the rated power. Assuming the generator was designed for gasoline.
As to whether one is more efficient than the other, I’m not sure. If we’re talking dollars to watt hours then my guess is natural gas or gasoline would win. Lots of things to factor in here.
Maybe @ESmith has a spreadsheet for this? 
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This. Lower cost portable generators can be extremely loud. Neighbor happiness might be a factor too depending on where you live. A neighbor would be in the right to call the police about noise from most generators. In Irving the ordinance is 50 dB at the property line at night which is not a lot of noise. Some of the portable generators are 80+ dB so you’d need a lot of space for that (or friendly neighbors, or no neighbors).
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Runtimes for gasoline are easy to come by; less so for propane or natural gas.
So I’m some sort of masochist and have compiled another list of generally >3k running watts inverter generators here. TL;DR is that propane is less efficient than gasoline, but a 20lb propane tank might have appreciably more energy than the generator’s gas tank thus propane can potentially offer more runtime … and there are tanks larger
than 20lb available.
The efficiency is pretty bad regardless. In the previous version of the spreadsheet, none of them so much as broke 9 kWh/gal using published specs; gasoline containing something like 33 kWh/gallon that’s <27% efficient. Propane might be more efficient from a thermal perspective, but I would bet it’s markedly less cost-efficient since gasoline (liquid, relatively easy to store and transport) is sold in huge quantities relative to propane (gas, much harder to store and transport).
Or an overbuilt enclosure that seriously dampens the noise.
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A couple of things here…
It is generally a defense to prosecution that one broke a law, ordinance, whatever, to the extent necessary to deal with an emergency. The state of Texas considers generators “essential” with respect to price gouging laws during an emergency, thus it is fair to assume that the state considers running a generator a necessity during said emergency. Your mileage may vary in front of a judge, which leads to…
Consider buying a generator with enough power to share with your closest or most whiny neighbor. Build a portable breaker box that limits how much current they can draw and forces them to stay within that budget. I haven’t done the research but I suspect a 15 Amp breaker (~1800 W) would power their fridge and furnace motor, though probably not both of them starting at the same time. Maybe even a TV too.
The same in Plano.
My theory on this sort of thing is let someone else be the test case and/or argue with the gendarmerie suddenly appearing on their property at an inopportune time.
My parents, who live on ~8 acres with the nearest adjacent residence several hundred feet and terrain and/or dens foiliage between them could make due with an open-frame generator and a shelter to attenuate the noise that they have to suffer. Distance buys you a good deal of passive attenuation thanks to inverse-square.
For most of us living in places with noise ordinances, an inherently quiet generator is probably more useful - while it may exceed 50dB it’s not likely to really draw notice. It’s also easy enough to start up ~monthly to keep the carb un-gummed and thus you’re probably more likely to keep it ready for an emergency.
As a compromise, an open-frame generator may open up budget for a well-engineered noise abatement strategy.
Sharing is sage advice no matter that the power budget. If nothing else USB power to keep devices charged will buy goodwill.
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I have a 3300 watt generator that I run dry every time I use it (2-3 times per year in the last few years). Anyone got any thoughts on whether that’s a sound thing to do? I’ve never had trouble starting it after refueling many months later.
For what you are describing, you have two routes.
- buy a shit gasoline generator, some jerry cans, and a bunch of extension cords. I wouldn’t buy less than 5kW.
You’re router and your fridge won’t really use all that much. I thought that the air handler in your furnace would probably use the full power budget when the fan kicks on, but others here seem to suggest they’re able to get away with it on a 3.5 kW. Either way, you’ll appreciate having the extra power when your wife wants a cup of coffee. Or that mini split a/c you’re talking about.
Anyways gasoline is preferred because it’s easy to come by as long as you’ve got an Oklahoma credit card. Get a gasoline model and you’ll find places to use it throughout the year. Get a Nat gas model and it won’t start when you need it because you never use it since it’s tied in place to a gas line…
Screw the noise.
- go buy a simple UPS for your comms equipment, a simple kerosene heater for your house, and then look for a used RV refrigerator that can run off a tank of LP gas.
Kerosene is easy to come by. A 12cf RV fridge will run almost 2 weeks on a 20lb propane tank. Go recharge the UPS overnight at the neighbors house when it dies.
Whatever you decide to do, DO NOT CONNECT THE GENSET INTO YOUR HOUSE CIRCUITRY . With a $600 budget, you’re not buying transfer switches or interlocks or anything to prevent a backfeed. People who backfeed the grid during an emergency deserve a special space in hell next to Billy Mays.
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Somebody’s co-worker’s bookie’s brother-in-law’s vague “I’ve got a guy” has relayed a story about someone that was always Johnny on the Spot on throwing that main breaker and running suicide cords to circuits on both phases and bippity boppity can run everything in a blackout no problem. I suspect this same person also wins every bet, makes an improbably fabulous income despite a lack of qualifications or even demonstrable work ethic, pays 30% less than the lowest possible price on everything, can talk their way out of a felony arrest, and can juggle 4 mistresses (or their male analogue) at once without breaking a sweat.
If they’re lucky, the breaker keeps popping since their little generator is trying to run their entire neighborhood and they figure it out before injuring any linemen.
During snowmageddon Lowe’s and Depot were out. I went to our only kerosene-at-the-pump place and while they were willing to sell it (limit 10 gallons) their pump was frozen up so nope.
For those who don’t know how an Oklahoma credit card works…
At 0:54
Based on my informal survey, completely draining the carb of fuel if storing for more than a ~month is recommended. Models that can shut the flow of fuel but not kill the ignition can do this with ease. If it’s worked for you for several years sounds like you’re golden.
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I would definitely recommend you keep doing what you’re doing. I didn’t once and had to dispose of bad gas, and clean out and rebuild a carburetor because of varnish and corrosion. You’d probably be replacing a small engine carb, but it’s still not fun.
I also recently took apart a carburetor that had sat outside on a tractor for about 15 years and it didn’t appear to have any real issues from sitting dry, so I wouldn’t worry about it.
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Re: generator noise
Most code enforcers have already recognized it’s a health and safety matter to run them. Some city’s such as Carrollton explicitly call out generators as exempt to make things clearer: https://www.cityofcarrollton.com/Home/Components/News/News/3771/
Unsure of Dallas and others having explicit rather than implicit protection, but Carrollton was on the front page of google results for looking up generators and noise violations.
As for backfeeding, unfortunately breakers don’t always trip for that. You may find that 100A breaker holds for the lineman who’s down the alley from you. When they cut my power for work at my old house they were very concerned to see I still had power until I told them it wasn’t on the main branch. They were working right behind my house on the transformer that ran the underground feed for the culdesac. They definitely would have gotten bit if I had backfeed.
The only time I’ve ever condoned a suicide cord is when their panel was setup with a cut plate which prevented both the branch that was fed by the generator and the main panel disconnect from being active at the same time. This was explicitly a temporary item in an odd case and the suicide cord destroyed with some satisfaction upon installing a proper transfer switch. I recall seeing something similar on hackaday recently when someone didn’t have a transfer panel either but they may have been hard wired in.
It’s a simple pigtail on the backside of a wall switch. Kill the house power, plug into an extension cord that goes through the pet door out to the caged patio and generator. The gen runs on about 8 gal of gas a day, and will go all night on a tank full (3.8gal).
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So I’m clearly a masochist and perhaps way too focused on analysis, but I’ve updated the spreadsheet to include pretty much all inverter generators with running watts ≥1500 and all the ‘profesisonal’ open-frame generators I could find in the time I allocated with THD matching utility power ≤5%.
Field of note:
-
Type
- Enclosed Inverter : Generally quietest, middling efficient, most expensive / kW
- Professional : Generally loudest, least efficient, and least expensive / kW
- Open Inverter : Generally quiet, most efficient, middling price / kW
- CC : Engine CC’s included because all other things being equal the generator with the larger engine will better achieve its faceplate starting and running watts
-
{FUEL} STATS : Also applicable to Propane Stats
-
Capacity : Gasoline tank size, gallons
(Propane stats use a fixed 20 pound tank, which the source claims to be 5.66 lb/gallon and I’m using in my calculations, however Professor Google says it’s 4.2 lb/gallon - YMMV) - Starting : The most-prominent stat about any generator (but not the most relevant), the maximum claimed watts the generator can supply for a brief period of time, often ≤ 30 seconds
- Running : The maximum sustained watts the generator is claimed to be capable of
-
Capacity : Gasoline tank size, gallons
- THD : A general indicator of power quality; lower is better, utility power is regulated to ≤5%, and I didn’t collect figures for all of the inverter generators because as a rule they’re all ≤5%
- Noise : Expressed on the very non-linear dB scale
- CC/kW : A larger figure generally means better performance - especially as the load approaches 100% of the rating
-
{FUEL} PERFORMANCE
-
Runtime : Hours at the percent of load
(With modest ingenuity the runtime of gasoline generators can be vastly extended with inexpensive bolt-on mods vis-a-vis a boat gas tank) - W : Watts at specified load
- kWh/tank : Net electrical production at specified load
-
kWh/gal : Theoretical efficiency at specified load
(Mostly of concern for long-duration operation ala living offgrid with the generator as a primary power source)
-
Runtime : Hours at the percent of load
Pricing, fine-tuning feature availability, and other data are left as an exercise to the reader. I do not claim the list to be comprehensive. Per professional ethics, this data is not to be construed as legal, engineering, professional, nor personal advice. I suspect that many models listed are no longer available. Offer not valid in Nebraska
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@John_Marlow, @lukeiamyourfather and others interested in noise levels,
Very good points, and you’re right. Noise is on my list to tackle, but it’s secondary to having the tool. As @ESmith mentioned, the cost savings should allow for a solid noise abatement solution. In a previous life, I built forced air ventilated enclosures for AV gear, including bringing a 110db guitar amplifier down to mid-60s (weighted a-slow). When I’m done (whenever that might be), I’ll try to take measurements.
@mdredmond great point, and I might fork over a little bit extra just for sharing. My neighbors are awesome, and I’d love to help them keep their heat on as well.
@JRay my heater is NG, so wattage is around 600w, 120v to run the heater/blower. I imagine starting wattage is higher, but I’ll need to check specs. I thought that refrigerators were kind of high (1200w or so). Is that just for startup?
@hon1nbo no suicide cables for me. I’ll do straight up extension cords to start (heavy gauge as needed). Ultimate plan is to put in a transfer switch and inlet that would not allow a possibility of backfeeding.
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