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Total Harmonic Distortion of Portable Generators

Mikey NY

Registered
Last Subscription Date
02/28/2016
wayne, I would thing that for occasional use it may be better to not have that gasoline in it, unless he exercise's it religiously. I know natural gas conversion is not cheap, but on the other hand, it will no longer have portability, so many pros and cons.
 

Wayne 440

Registered
I assumed that "very occasional" use of the set would include proper preparation for long term storage. If it will not, I agree.
 

Power

Registered
wayne, I would thing that for occasional use it may be better to not have that gasoline in it, unless he exercise's it religiously. I know natural gas conversion is not cheap, but on the other hand, it will no longer have portability, so many pros and cons.
If you want to have power in big events, like Texas, Florida and Puerto Rico storms, you cannot rely on natural gas. It is often shut off because of infrastructure damage or because the gas compressors loose power.
 

Andrew Mackey

Moderator
Last Subscription Date
05/14/2017
Natural gas will not affect voltage, nor operation of the engine under most conditions. It can affect power output (-20%) of the engine. This in turn may or may not affect the generator output under peak load. If the engine has more power than the generator needs to deliver and maintain maximum output, using NG won't affect operation. If engine HP is close to the needed HP input to maintain voltage/amp requirements (RPM), then using NG may be problematic. The engine might not be able to keep up with the demand. You would need to see the engine output specs as well as generator delivery requirements, to see if NJ will work for you.
 

GeneratorNewb

Registered
So basically, is it not worth it to purchase a portable generator unless it is an inverter generator? The largest 1 I know of is the Honda eu7000is and that runs $4k.
 

Wayne 440

Registered
So basically, is it not worth it to purchase a portable generator unless it is an inverter generator?...
I sincerely hope that isn't the case. I have a bunch of portable(*) generator sets and none of them are inverter designs.

*note - "portable" does not mean that lifting or loading machinery will not be required.
 

Graycenphil

Registered
Last Subscription Date
02/16/2012
Some time back, someone on here tested a Honda EU6500 and found it had a pretty perfect sine wave. If that is true, I wonder if it might not be the best choice?

You will pay more for the generator, but you get a great generator. And you aren’t risking replacing expensive electronics on the furnace. Or, worse yet, not even being able to replace expensive electronics if they are only available from the manufacturer.

Might actually save you money in the long run.
 

Fred M.

Registered
My impression is that the EU7000i Inverter is similar to the EU6500i Inverter, but the engine was updated.

I have the EU6500i, which was used during a couple of hurricane outages and an ARRL field day. I have not used it where I thought waveform was critical.

Fred
 

Thaumaturge

In Memory Of
Age
68
Last Subscription Date
07/12/2019
So basically, is it not worth it to purchase a portable generator unless it is an inverter generator? The largest 1 I know of is the Honda eu7000is and that runs $4k.
If question is mainly one of not damaging an expensive heater... exactly how much power does the heater draw? Walmart sells a 1000W pure sine inverter for ~$130. Charge a car battery off your generator and feed a pure sine inverter off the battery. Can you feed just the electronics controller separately? Amazon sells a pure sine 300W inverter fot ~$44.
Upwards from 1000W the price of pure sine inverters goes exponential.
Doc
 

GeneratorNewb

Registered
Interesting concept but between the cost of the battery, inverter, and cost to isolate furnace with a separate hookup, it is probably easier to invest in a separate inverter generator for thr furnace or just upgrade to the eu7000is. I guess I just don't know if the 5,500 running watts of that generator is enough to run a well pump, refrigerator/freezer combo, deep freezer, gas hot water heater, gas furnace, router, modem, and a few led lights.

The other option that stuck out was the EM6500s which is a non-inverter Honda model.

Other than that, I may just spring for the 8k continuous /10k peak Briggs and stratton model and hope the large capacity is enough to prevent any big jumps in frequency. I'm however not too fond of the brush alternator.

As much as I'd like to convert them to natural gas, it seems self defeating if it will result in a drastic decrease in output.
 

Graycenphil

Registered
Last Subscription Date
02/16/2012
I think 1,000 watts would run your furnace, though it might be tight starting the blower motor. Others on here probaby know more precisely. But I would queston that cheap inverter. Is it really 1,000 watts, is it 1,000 watts peak, how many watts can it run continuously and how long will it last? Is it even really a pure sine wave?

I think the EU6500 or 7000 would run all those things, except probably not the water heater, at the same time. In our house, when we’re running on the generator, I turn off the circit breaker for the water heater. When I know we won’t be using any other large loads for a while, I’ll turn on the water heater until it heats the whole tank, then shut it off again. That usually suffices for a whole day.

The other nice thing about the Honda EU generators is they are really quiet.
 

armandh

Sponsor
Last Subscription Date
09/02/2010
once again
if it is just the expensive furnace controls that are in question,
and the furnace is not yet purchased, quit screwing around AND
get a furnace known to play well with an imperfect generator.
have you called the HVAC contractor yet?

my last post on this topic!
Armand
 

Power

Registered
don't know if the 5,500 running watts of that generator is enough to run a well pump, refrigerator/freezer combo, deep freezer, gas hot water heater, gas furnace, router, modem, and a few led lights.
Gas fired hot water heaters are usually self powered- use a pilot millivolt system. I have not seen any with a connection to 120 volts.

You need to read nameplates and add up all the watts you want to run concurrently to see what size generator you need.
The smallest that will do the job is best. more fuel efficient.
Slower is better. 1800 RPM is much better than 3600 RPM.
More oil in crankcase is better,
Pressure lube with oil filter is better.
 

Graycenphil

Registered
Last Subscription Date
02/16/2012
Thanks Power - I missed the gas part, and I was even wondering if it might be.

In that case, if you decided to get a Honda EU, it should have no trouble running all those things. I agree about the smallest size that works being the best. But the inverter generators are a bit of a compromise there, getting pretty good fuel use when running a small load while still being able to run most of the house if needed.
 

GeneratorNewb

Registered
Lots of good information here and I really appreciate everyone's insight! Does anyone have an opinion on the Honda EM6500s. It provides the same power output as the Eu7000is but at about half the price (5.5k continuous with 7k peak). I've read that the iAVR system is supposed to be pretty good about keeping voltage and frequency under control but I don't know the exact numbers. I like the whole concept of having a brushless alternator. I can get this unit for $2.2k.

The Yamaha EF7200DE is even more affordable and better specs at 6k continuous and 7.2k peak. It also has a brushless alternator. However, the thd numbers aren't posted and I don't know how tight the frequency control is either. I can get this unit for $1.4k

The Briggs and Stratton 30679 has 8k continuous and 10k peak with a thd of 3-6% but has a brush alternator and made in China. I can get this unit for $1.2k.

What would you guys go with and is it pretty much guaranteed that there would be a 20% drop in power output with a natural gas conversion? I like the accessibility of NG (love in northeast so I've never experienced a NG outage) and the ability to keep the carb super clean. I should also mention that it's super rare that we lose power for more than 24hrs. Maybe once every 5 years. Thanks again!
 

Graycenphil

Registered
Last Subscription Date
02/16/2012
Those are both excellent generators, but they aren’t EUs. I believe that only the EU series inverter generators will give you power quality similar to that of the electric company. As others have said, in many cases this will not matter, but if you do wind up with a sensitive furnace, it may. I think Armandh is totally right that the best thing would be to have a furnace that will not be bothered by less than perfect power, but this may not be an option.

Since I now realize that your heat and hot water are gas, you should be fine with a 6500 or 7000 running on natural gas. Most conversions would still allow you to run on gasoline too, so if there is a major disturbance, and you can find gasoline, you can still make electricity. Following hurricane Sandy, some areas had no natural gas service for a while. At least in the beginning though, gasoline was pretty hard to get too.

Another possibility would be to find an older generator, possibly an Onan, in good condition. It would almost certainly cost less, maybe much less, than any other options, and might make cleaner electricity than any but the EUs. You will have no warranty, but you will have a better made and probably longer lasting unit than almost any new generator in your price range. It will also be cheaper and easier to repair, if it ever needs it.
 

GeneratorNewb

Registered
I have my mind set on a specific furnace for reasons I won't get into so switching unfortunately isn't an option. I suppose I could power up some space heater in a smaller room to stay comfortable but obviously not ideal for freezing pipes etc. I could also shut down all appliances and make sure it is exactly 60hz when the furnace is running by itself. Another option is the Kohler Pro9.0e with their tri-fuel kit. I called Kohler and they said that the output on gasoline (7200w) is identical on gasoline and natural gas but couldn't explain how so I'm naturally apprehensive. The dB rating on it is pretty obnoxious though at 79dB.
 

Graycenphil

Registered
Last Subscription Date
02/16/2012
I hope I’m not sounding like a Honda commercial, but I’m really thinking one of their EU generators is the best bet for you. If you are without power for days, or weeks, you are going to want to run the furnace. If you run it on the Kohler and it fries your circuit board, you’ve lost all the savings on the generator, plus you have no heat until it gets replaced. And if the power isn’t back on then, you still have no heat. One frozen pipe could cost more than the price difference in the generators too.

I also believe the Honda will last much longer than that Kohler. There are lots of stories of them running for thousands of hours.

Perhaps a used EU6500? They all have hour meters on them, so you can tell how much use it has.

79db is pretty loud. A lot nicer than freezing, but still loud.
 

GeneratorNewb

Registered
I considered the eu6500 but they still command roughly $3k and aren't fuel injected like the eu7000is. I guess I'm having a hard time spending $4k on something that's rarely going to be used (I bought the wh7500e and haven't used it once in 3 years). Maybe I'll just wait until they come down in price.

Do you think the EM6500s is a viable option? I know the EU is phenomenal on gas though and gives the peace of mind of using electronics. Thanks again!

My only concern is that with all I have going on in the house, I may be bumping up against that 5.5k running watts fairly often. Thanks for listening to all the banter!
 
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