Conventional Vs Inverter Generator

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  #1  
Old 07-07-14, 07:39 PM
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Conventional Vs Inverter Generator

Situation:
- I can get a 2.8 KW inverter generator and 5 KW conventional generator for about the same price.
- I will be using a lockout, and standard 30 Amp 240V style plug on the outside.
- I don't need 240v during a power outage. The only thing that uses 240v is the AC.
- It's for emergency use.

Inverter Advantages:
- In used generators, the inverter generators cost about twice per KW, and while the sine wave may not be as smooth, they more than make up for it with accurate control of voltage and cycles.
- Generally, for the extra money you get a quieter generator since there isn't a 1:1 relationship between cycles and rpm, a better muffler, and better fuel economy.
- The inverter generator does not have to oversized as much because it is not center tapped. The full 120V current capacity is available to any circuit.
- No balancing of legs has to be done.

Inverter disadvantages:
- Cost more to repair
- You get half the total KW for the money
- No 240V in case I lend it to someone who needs it for a 240V well pump.

Summary:
I'd have to make up a special cord for the inverter generator, but it is tempting. If you have some thoughts as to which one you would pick, let me know.
 
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  #2  
Old 07-07-14, 08:28 PM
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If you're using it just for emergency power, get a good quality conventional unit. The inverter units are nice, but they lack the power to start anything with a decent motor. What all you need to power is another consideration. If all you're powering is the fridge, TV, and a few lights you're going to best with a small (about 3KW) portable, but if you plan on running any electric heat, and electric stove, etc. you'll need a bigger unit.
 
  #3  
Old 07-07-14, 10:24 PM
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We're all gas here. The only 240v we have is the AC. The only thing I need to be sure works is the furnace, and the microwave would be nice. Everything else are lightweights.
 
  #4  
Old 07-07-14, 10:31 PM
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I think you'd be best with a 3-4 KW generator. How much are you looking to spend? Do you want a generator that will run off Gasoline, Diesel, or your LP or Natural Gas supply?
 
  #5  
Old 07-08-14, 12:21 AM
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I have a Yamaha EF3000ise inverter generator that I converted to use gaseous fuel (propane or natural gas) exclusively. I have no trouble whatsoever powering my refrigerator, furnace (gas-fired), Internet equipment (including telephone), television, video recorder or DVD player a few lights and either a counter-top oven, microwave oven or 1100 watt hotplate.

I set up my transfer switch and inlet to accept a standard 240/120 volt generator feed although my gennie is 120 volt only. I modified the gennie by installing a four-pole receptacle with both "hot" terminals paralleled and this means that either I or any future owner could connect a standard generator with no changes in the house's electrical system.

I personally feel that the higher quality power from the inverter is an asset and the quality of the engine, generator and inverter are significantly better than the average conventional generator. Yes, it DID cost significantly more than a cheapo but when I need it I want it to be there for me.
 
  #6  
Old 07-08-14, 06:29 AM
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Hi

I have the Honda Eu6500. Runs the entire house excluding AC. I have natural gas pretty much everything however.

My neighbor has the conventional type around 6K. He has to had to replace it twice (warranty) already and always seems to have issues with it during his monthly run cycle.

The Honda I've not had any issues (do all of the maintenance myself - purchased the service manual online). It starts first time everytime - touch wood!.

I can have a conversation standing beside the Honda when it is running and my neighbor can't even hear it in his bedroom which is beside where I run it (about 30 ft or so.). His I can hear from at least 200 ft away.

In economy mode during Sandy we consumed about 3 gallons a day vs about 6 for his. We both ran it during the day for about 12 hours or so. He was at the gas station in the queue frequently. I have around 20 gallons storage capacity which will normally run me close to a week (I have a outboard boat motor tank).

I work from home in IT so the clean power cycle was important for me (at least I think it is - no experience with the conventional type). Also I travel alot and hence my wife needs to be able to start it up if required - the Honda is pretty straight forward solution. We lose power for at least 3 hours or so during most thunderstorms so it gets a good work out during the summer months - any ice storm generally knocks us out again as well.

The 6500 is probably a little overkill in my situation however I have a bunch of multiwire branch circuits in my house and therefore I needed 240V output. So given my preference for inverter and also the 240V requirement I went with the EU6500.

When the warranty expires on the Honda I will convert it to Natural Gas.

You will need to make a special cord for the inverter at 3.8KW generator - my approach would be what Furd has done in this situation.

So for me it was Clean Power, Fuel Economy & Maintenance that made me spend alot more money!
 
  #7  
Old 07-08-14, 06:34 AM
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Furd said: I have no trouble whatsoever powering my refrigerator, furnace (gas-fired), Internet equipment (including telephone), television, video recorder or DVD player a few lights and either a counter-top oven, microwave oven or 1100 watt hotplate.
That's logical to me. When working on 120V only, a 2800 watt inverter would outperform a 5000 watt center-tapped conventional with regard to 120V starting power, and there is no load balancing required without the capacity being divided in two by a center tap. That allows the starting load to float anywhere needed.

The 5kw could run more small loads, but sizing is complex requiring running watts, starting watts, and balancing. My current thoughts are that for 120v, a 3kw inverter would be about the equivalent of 5kw conventional. I don't believe I can afford to be much south of 3kw.

Furd said: I have a Yamaha EF3000ise inverter generator that I converted to use gaseous fuel (propane or natural gas) exclusively.
I've been considering that. I know of several ways to do that, from assembling your own, to buying NG carburetors, to 3rd party kits like US Carburetion sells. Which method did you go with?

The engine takes a power hit on propane, and twice that on NG, especially with engines not designed for them. There is no getting around exhaust valves taking on more heat due to the slower flame travel, but as long as the engine can get rid of the heat... Propane fares better, but last winter was priced the same as gasoline per therm, road tax and all, so gasoline would have been more economical. There is no beating NG on price, but there is a 23% performance hit. If you're pull off what you've written on NG, I'm encouraged. I may try gasoline first, and then rig a temporary NG setup to see if it is tenable in my situation.

Thanks!
 
  #8  
Old 07-08-14, 06:54 AM
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When working on 120V only, a 2800 watt inverter would outperform a 5000 watt center-tapped conventional with regard to 120V starting power, and there is no load balancing required without the capacity being divided in two by a center tap.
I modified my gen for 120v only. Its only 3250 watts, but runs my well pump, refridge, lights, tv, ect... But now a few brands make them, or they have a switch for 220 only.

If you want to stay small the champion is OK and cheap.. About $330.. 120v only.

46516 - Champion Power Equipment


I have a Coleman of the same size as the champion and only used 12 gallons of gas during sandy...
 
  #9  
Old 07-08-14, 07:02 AM
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Here is basically the coleman I have. Mine was 120/240, but I converted it to 120v only just how this one is..

This is 120v only.

3250 Watt Portable Generator with Manual Start.


Here is one thats 120v and propane..

3250 Watt Liquid Propane Generator with Manual Start


And of course here is a unit with both outlets.. 120v only or 120/240v...Problem is these gens are much bigger...

6500 Watt Portable Vx Generator ELECTRIC START
 
  #10  
Old 07-08-14, 07:11 AM
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mick999 said: I can have a conversation standing beside the Honda when it is running and my neighbor can't even hear it in his bedroom which is beside where I run it (about 30 ft or so.). His I can hear from at least 200 ft away.
That's also on my mind. You can spend a lot of money trying to shut up a loud generator, and still not get anywhere. I hear the exhaust being drowned out by rocker arms ringing tin valve covers, shrouds ringing, recoil starters rattling, ball or needle bearings using the engine case for a sounding board, etc. About the only thing that works reliably is to put it inside of a Rubbermaid enclosure with sound insulation and an exhaust fan.

mick999 said: In economy mode during Sandy we consumed about 3 gallons a day vs about 6 for his.
That's another thing on my mind. When the high rpm is not required to control the cycles, you can run the engine at lower rpm and higher cylinder pressures, which makes it much more efficient.

mick999 said: I work from home in IT so the clean power cycle was important for me (at least I think it is - no experience with the conventional type).
You described me too. I don't know how good a power we need. I know computers aren't very voltage sensitive. Electronic inverters can't really make a true sine wave, but if they can control the wave form close enough, and control the cycles and voltage better, it seems to trump the true sine wave from a mechanical alternator that can't maintain cycles and voltage. The only problems I've heard with conventionals in our field is clocks not keeping time, and Standby UPSes not surrendering the AC back to generator because of the power not being good enough. That probably wouldn't be a problem for an RT UPS.

mick999 said: ...however I have a bunch of multiwire branch circuits in my house and therefore I needed 240V output.
I guess I don't see the relationship between multi-wire and 240V, but the EU6500 would be a dream machine. I can't spend that much for something that would get used on average for 4 hours every other month.

Thanks!
 

Last edited by IT_Architect; 07-08-14 at 08:11 AM.
  #11  
Old 07-08-14, 07:27 AM
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The new version of the Honda EU6500 is the EU7000 (5500watt). It costs $4,000. You can have a Generac 11kw w/whole house switch for $1,000 less - making up most if not all of the cost difference in installation. Natural gas - no chasing gasoline - with fully automatic backup.
 
  #12  
Old 07-08-14, 08:18 AM
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patmurphey said: The new version of the Honda EU6500 is the EU7000 (5500watt). It costs $4,000. You can have a Generac 11kw w/whole house switch for $1,000 less - making up most if not all of the cost difference in installation. Natural gas - no chasing gasoline - with fully automatic backup.
I don't know where they are that inexpensive, but that would be the way I would go if I were going to spend that much.

Thanks!
 
  #13  
Old 07-08-14, 08:26 AM
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I guess I don't see the relationship between multi-wire and 240V, but the EU6500 would be a dream machine. I can't spend that much for something that would get used on average for 4 hours every other month.
I have around 12 circuits in my house that are multiwire (I've been slowly replacing them as I do certain things around the place....) - anyway in a multiwire branch circuit you have 2 hots, 1 neutral and 1 ground. The neutral is shared. The design theory is that since each leg is 120V potential difference to the neutral, the load back on the neutral to the panel should be 0 if the loads on each leg is the same. Therefore you can save the cost of running another neutral and ground. (ie in a normal 2 120V circuit setup you would have 2 hots, 2 neutrals, 2 grounds). However if you hook up both hots on a multiwire circuit to the same side on the generator or the electrical feed (via either the cable you are proposing or parallel the generator output) then you have two hots potentially pulling 15amps (total 30amps) and that 30amps is then traveling back down the neutral which is only rated for 15amps. Thats my understanding anyway. Not ideal..

If you don't have any multi-wire circuits then you don't have this problem!

Yes it hurt paying that much for a generator but its been 4 years and she is still running well So well that I haven't got around to switching it over to Natural gas as yet... Just have to remember fill up the 20 gallons before each storm and if I don't use it - it goes into the car.

My UPS happily switches back to the generator when I get it up and running.
 
  #14  
Old 07-08-14, 08:29 AM
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I paid around that price delivered... Don't buy it during a storm and the internet places will email you a better price than they list online. Both Honda and Yahama have agreements with distributors that the list price is always shown on the websites. Was going to get a converted NG Yamaha but it wasn't in stock and they couldn't give me a delivery date - So I went with the Honda.
 
  #15  
Old 07-08-14, 08:30 AM
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lawrosa said: Here is basically the coleman I have. Mine was 120/240, but I converted it to 120v only just how this one is...
I'm glad I asked on this forum. There has been a lot of useful insights to draw from.

For inlet, I'll probably go with the 30 Amp socket that has the socket facing down and a flip door, a lockout for my panel from SquareD, and a 30 Amp breaker. If I go 120V, I'll need to special wire a cord. Since the circuits are connected to the panel ground, I'll need to be able to float the generator.

PS: For some reason, my threading on the forum is messed up. My replies are not under the messages I responded to. I must be doing something wrong.

Thanks!
 
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Old 07-08-14, 08:45 AM
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I'll need to be able to float the generator.

All the colemans are floating neutral. Hence why I bought it. I dont think they changed that with the new gens compared to the older.
 
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Old 07-08-14, 08:49 AM
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mick999 said: The design theory is that since each leg is 120V potential difference to the neutral, the load back on the neutral to the panel should be 0 if the loads on each leg is the same. Therefore you can save the cost of running another neutral and ground.
I can see the sharing neutral and ground. The rest I would have to think about... LOL! That is something I haven't encountered.
 
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Old 07-08-14, 08:52 AM
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Its emergency power. How many circuits do you really need? 3600 what gen max... Refridge? A few lights? TV?

Reliance Controls 30114A 30-Amp 120V 4-Circuit Indoor Transfer Switch

Reliance Controls R30114B 30-Amp 120V 4-Circuit Outdoor Transfer Switch
 
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Old 07-08-14, 08:54 AM
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The design theory is that since each leg is 120V potential difference to the neutral, the load back on the neutral to the panel should be 0 if the loads on each leg is the same. Therefore you can save the cost of running another neutral and ground.
I believe as long as you stay under 4000 watt gen the multicircuit issue is not a problem.. From what I read anyway...
 
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Old 07-08-14, 08:56 AM
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lawrosa said: All the colemans are floating neutral. Hence why I bought it. I don't think they changed that with the new gens compared to the older.
Now I need to just make up my mind and buy.
 
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Old 07-08-14, 09:00 AM
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Deleted......................
 
  #22  
Old 07-08-14, 09:01 AM
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I've made it through many power outages on my Generac 4000 EXL. It powered all my receptacle and lighting circuits, which included a fridge, deep freeze, oil burner, and either the microwave or another cooking appliance.

I'll need to be able to float the generator.
I wouldn't worry about that too much.
 
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Old 07-08-14, 09:03 AM
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I'll need to be able to float the generator.
I wouldn't worry about that too much.

Why not? Code says you cant have two bonds...
 
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Old 07-08-14, 09:08 AM
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Why not? Code says you cant have two bonds...
Because then you can't use the generator as a standalone unit. If anything, the o/p is best using a neutral switching transfer switch.
 
  #25  
Old 07-08-14, 09:12 AM
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I experience no power loss when running on natural gas. I loaded my unit up to in excess of 2800 watts and it ran perfectly. The voltage will take a sag of maybe 1.5 volts (from 121) when going from minimum to maximum load and a spike of about the same amplitude when going from maximum load to minimum. The voltage stabilizes back to 121 in less than a second after these major load excursions. The frequency excursions have been almost impossible to measure but seem to be no more than 1/2 Hz either way on the major load excursions. I haven't been able to apply an oscilloscope so I can't say as far as power quality may be concerned but I have read that the inverters put out power very close to a pure sine wave and with few harmonics.

I did use the kit from US Carburetion for my conversion and the hardest part was having to buy another phenolic block to fit between the modified carburetor and the intake port. I was able to mount the zero governor inside the shroud and I cut the top off the gas tank to use for a tray to hold the gas hose, power interconnect cable, and other items, accessed through the original gasoline filler hole in the shroud. Externally the only visible differences are a conduit hole closure instead of the gasoline tank cap, a one inch rubber grommet on the side shroud to allow access to the zero governor primer (not used) and a bulkhead fitting on the pan just ahead of the wheel (control panel side) for the gas hose connection. I can have this up and running in about five minutes when necessary.
 
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Old 07-08-14, 09:34 AM
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Because then you can't use the generator as a standalone unit. If anything, the o/p is best using a neutral switching transfer switch.
When I power my RV with my gen I use an Edison plug..

Generator Ground-Neutral Bonding | No~Shock~Zone
 
  #27  
Old 07-09-14, 07:33 AM
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patmurphey said: The new version of the Honda EU6500 is the EU7000 (5500watt). It costs $4,000. You can have a Generac 11kw w/whole house switch for $1,000 less - making up most if not all of the cost difference in installation. Natural gas - no chasing gasoline - with fully automatic backup.

IT_Architect said: I don't know where they are that inexpensive, but that would be the way I would go if I were going to spend that much.

Thanks!
Here:

Generac Guardian 6438 11kW Standby Generator System 200A Service Disconnect + AC Shedding
 
  #28  
Old 07-09-14, 05:16 PM
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Having clean power for electronics is really important. We discussed this quite a bit already. The inverter generators will give you quality power. You can get regular generators that give good power, but they are not the cheapo discount units.

I purchased the Yamaha EFi2800 from the same company Furd mentioned. I had them do the conversion for me so it will run on propane, natural gas, or gasoline. It doesn't suffer any power loss running on propane or natural gas. Supposedly the warranty is still valid because they are an authorized dealer and repair.

I have yet to use it in an emergency situation, but it will run my boiler, refrigerator, and some electronics. My goal was to have about a 20 amp circuit available and this particular generator is a bit more than that.
 
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Old 07-09-14, 08:44 PM
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Having clean power for electronics is really important.
Most consumer electronics have switching power supplies which could care less what you feed them as long as it's within 100-240V. If you're willing to spend the money on an inverter unit, and plan on using it frequently (if you live out in the sticks or go camping or tailgating you'll use it quite a lot) it'll be a good investment. I saw someone post a standby unit. If you just plan on using the generator for power outages, you're best with that. They self-test every week, get tied into your home's propane or natural gas supply as well as automatically start. Just be sure to do the required maintenance, which is relatively easy.
 
  #30  
Old 07-11-14, 05:41 PM
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Switching power supplies is not going to protect you from noise. Electronics in appliances such as furnaces and boilers do not have those types of power supplies.
 
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