# How much natural gas is required for portable generator?



## Tboney (Sep 9, 2020)

I have a couple of gasoline generators but am thinking about a tri-fuel, somewhere around 4000 watts running size. During the last major hurricane we suffered through (Katrina) gasoline was hard to get and propane was even harder. The only easily accessible natural gas line I have is a 3/8" copper line that used to feed a gas grill. I'm a decent electrician but know practically nothing about gas. Anybody know whether my gas line would supply enough natural gas for this sized generator? Thanks.


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## FlyFisher (Jun 30, 2018)

My 2600w rotary generator runs (weaker) on a 3/8" grill port.



















I am not sure how much bigger I can go on that line. And I have not fully load-tested that generator on that connection.

I have a larger 15kw rotary unit that wouldn't run on the grill port so we upgraded the main house feed with another port and valve (all 1" at the meter, 3/4" flex pipe (yellow) to gen) for the generators:


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## Tboney (Sep 9, 2020)

That's what I was afraid of. Looks like I'll stick with my gasoline. I try to keep a 3-4 jugs full during hurricane season. Thanks for the info.


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## iowagold (Jan 22, 2020)

one inch id line rocks on feed line to the point of use!
pm me for pix and part numbers for my manifold setup


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## Tboney (Sep 9, 2020)

iowagold said:


> one inch id line rocks on feed line to the point of use!
> pm me for pix and part numbers for my manifold setup


Thanks Paul. I just don't think that's gonna be feasible for me. My gas meter is on one side of the house and my electric service (underground) comes in on the total opposite side. I would either have to run a long gas line or a lot of heavy wire to a suitable location for them to meet up with my generator. We don't have a lot of power outages so I think I'm gonna stick with my gasoline powered gennies.


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## exmar (Jun 29, 2015)

Also keep in mind that a 4000W generator is on gas, LPG drops power 10%, NG drops an additional 5-10% (I forget) so if you want 4000, buy larger.


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## Tboney (Sep 9, 2020)

exmar said:


> Also keep in mind that a 4000W generator is on gas, LPG drops power 10%, NG drops an additional 5-10% (I forget) so if you want 4000, buy larger.


That's true. I'd probably need a 5000 running and I don't have the gas supply for it.


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## iowagold (Jan 22, 2020)

Tboney said:


> Thanks Paul. I just don't think that's gonna be feasible for me. My gas meter is on one side of the house and my electric service (underground) comes in on the total opposite side. I would either have to run a long gas line or a lot of heavy wire to a suitable location for them to meet up with my generator. We don't have a lot of power outages so I think I'm gonna stick with my gasoline powered gennies.


soooo...
do you have a basement?


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## Tboney (Sep 9, 2020)

iowagold said:


> soooo...
> do you have a basement?


No basement. House is on a slab foundation.


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## iowagold (Jan 22, 2020)

yea.... slab is bad....
but you still can run under the house the electrical feed from the gen.....
just a total pain vs a basement....

so where is the breaker panel and the gas meter?
draw up a sketch for us...

I was lucky on mine and only had to do 35 feet of the 4/O in metal conduit to the new breaker box location...
and the generator feed inlet was only 40 feet to the new panel to divide up the distance.
and my gas feed is 20 feet from the meter at one inch id for the gens.

i was able to place the new 200 amp breaker panel just off the kitchen for super easy access for an interlock inside the building!


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## FlyFisher (Jun 30, 2018)

Tboney said:


> My gas meter is on one side of the house and my electric service (underground) comes in on the total opposite side. I would either have to run a long gas line or a lot of heavy wire to a suitable location for them to meet up with my generator. We don't have a lot of power outages so I think I'm gonna stick with my gasoline powered gennies.


I highly recommend that if you have natural gas that you do everything you can to use it. There is no other option that makes sense - if you have NG use it. 

The reason being as long as you HAVE natural gas you have unlimited fuel. You don't have to tank fuel in - either propane, gasoline, or diesel. It is piped in to you. That is a massive difference. It does not matter what the price of the gas is - it will absolutely be cheaper than propane, diesel, or gasoline - let alone the fact you don't have to transport it in tanks. 

Work up the fuel consumption and you'll see quickly how much fuel you will run through in an extended outage. 

My 15kw unit - a ballpark consumption on gasoline is 1.5gal/hr, or 36gal/day. For a 7 day outage that is 252 gallons a week.

Converting to propane - the numbers are 4lbs propane/hr or 96lb/day. Keep in mind, also, that propane tanks shouldn't be depleted lower than about 30% of tank capacity (it has to do with pressure - the lower the volume of fuel in the tank the lower the pressure - and when you get down to a certain point your flow out of the regulators won't be enough to sustain the draw from the gen = it will shut off when you still appear to have "fuel in the tank"). Using the same numbers that is 672lbs/week of propane. 

The point - fuel consumption adds up. If you have an unlimited supply piped in - you need to use it. 

The question is what happens when you DON'T have natural gas? I have worked on a situation in a prior job where there was a major gas leak and the utility feed was cut off to a whole neighborhood while a road and sidewalk were excavated to fix the line. It do happen. If a tree gets knocked over in a storm and the roots tear in to a gas line - what happens? The point - you most certainly can loose your natural gas feed. At that point you are forced to tanked in fuels - propane, gasoline, diesel.

On the same token of loosing natural gas - what would make the most sense is to have a generator that was as fuel efficient as you could get. That way you get the most "mileage" out of the fuel that you can get. Gasoline for example - if you have 10-15 gallons on-hand and you have 2 cars that, lets say, combined have another 15 gallons (I don't know many people that keep their vehicle tanks topped off every day) that you can siphon if need-be that ~30 gallons of fuel won't last long in, say, a unit the size of my 15kw. That won't get 24hrs. However, on a small inverter generator that could last you a week. BIG difference. 

In the above scenario - if you DO NOT have natural gas - the object is how small of a gen you can get by on so that you get the longest run time on the fuel you do have. The other note here is that there is a "minimum fuel consumption" of a generator. This is the point at which, on inverter gen's specifically, the engine, in eco mode (non-eco mode is higher engine RPM at "idle" = higher fuel consumption, but less start up delay), starts to use "more fuel". In order to make "more power" you need more fuel and air. However, to keep the engine idling it uses some fuel and air just to idle. It also can produce some power down that low. However, the question is - at what wattage draw does the engine need to add fuel/air to make more power beyond that of idling??? The bigger the generator the higher this is, but the bigger the generator the more fuel, period, the unit is going to draw at idle. So at night when no one is awake and there are only a couple fans drawing around 100 watts with the refrigerator on standby (plugged in, no compressor running) - you are wasting fuel with the generator running at idle. When the fridge compressor kicks on and the load hits the gen then the gen will throttle up to start the compressor and then it will drop down in RPM as the running load of the compressor is less - it may get down to idle, maybe it will run at just a tad higher. In this case, you are maximizing the fuel efficiency - you are converting the most energy of the gasoline burned to electricity consumed. Running at low loads is a waste of fuel - and is also hard on generators (engines need to run at higher loads routinely to heat them up and keep carbon deposits down, propane and natural gas do burn a lot cleaner, though).




Tboney said:


> That's true. I'd probably need a 5000 running and I don't have the gas supply for it.


My vote is to get a valve added off the meter like what we did. You can get flex pipe - which is what I used. They make that in all sizes. If you have 1" supply like us keep it 1" as far as you can. I already had the 3/4" line so it is what I use and it works pretty good here (33ft of flex pipe). If you are only anticipating using it on rare occasions it wouldn't be too hard to lay out the flex pipe when you need to use it, then put it away when done.

If you wanted a more permanent install then laying galvanized iron pipe would be good. Black iron will rust if not treated/coated/painted. Galvanized is already coated. 

All stuff to think about. Good luck with it!


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## iowagold (Jan 22, 2020)

use black pipe then prime and paint it.
it is rated for LP and NG.
it is the industry standard.
and use good full port brass valves!
jomar makes some nice valves.
pm if you need links!

NG is way way cheaper per run hour....
if you have NG!

second choice is diesel for run cost...
but then you are looking at expense to maintain a diesel...
but gallon for gallon it has more energy...
and the late model computer controlled injected diesel gens are super good on fuel!

same on the gasoline and LP and NG fuel injected engines.
10% to 30% better on fuel consumption.
and they deal with the hot cold start better!
no choke to deal with!
the sensors take care of that fuel enrichment map.
super cool when the engine is at that temp where it is not cold and not hot starts...
no more wasted fuel at startup.
perfect for an modern auto transfer system.


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## Tboney (Sep 9, 2020)

After considering everything I am re-thinking my whole plan. Either one of my generators will easily power all of my 120 volt circuits. (Will have to be careful running the microwave, hair dryers, etc. with the little Champion) My son has a small window ac he doesn't use so I think (in case of an extended outage) I'm gonna stick his window unit in my master bedroom window. It should keep the BR and the master bath reasonably cool in the summer if I shut that part of the house off. On the gulf coast I don't have to worry about ice storms so winter outages are not a big concern. I've got a gas stove and gas water heaters so I'm ok there. I won't have any 240 volt service (clothes dryer or central air) but we can make do without them for a while.
I said I wasn't interested in a dual fuel gennie to but I'm rethinking that also. I counted up the 20 lb propane bottles that my son and I both have and we have 8 between us. Most are full and a trip to Costco will take care of the ones that arn't. In addition I have plenty of 5 gallon gasoline cans and my truck has a 36 gallon tank. I keep it topped off during hurricane season. I am looking at a







Champion 200991 3500W/4500W Inverter Dual Fuel Electric Start Generator

I can just see it now. Me and the dog in the cool bedroom watching Gunsmoke while my wife cooks in the hot kitchen. Ahh, breakfast in bed.


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## iowagold (Jan 22, 2020)

we use one of the role around portable air con units.
they work well on small gens.
and nice for if you need to cool another space too!
just do the duct vents in every room or garage space for fast connection.
or get the optional window adapter for the vent.

there are also new inverter versions of these portable air con units!
just hitting the market fall 2021.
cool times in deed!


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## FlyFisher (Jun 30, 2018)

Tboney said:


> I can just see it now. Me and the dog in the cool bedroom watching Gunsmoke while my wife cooks in the hot kitchen. Ahh, breakfast in bed.


That sounds like a pathway to a permanent boot out of the house. 

I have looked at that Champion also. That and Duromax has one out, or coming out, that is a dual fuel inverter around 4500w. 

You hinted at this in your post - that class of generator DOES NOT have 240v. They only do 120v. There are only a couple rare models under about 6kw, as far as inverter units go, that do 240v. I do not think this is a point to fret over - as you say all the loads you intend to run are 120v anyway. That leaves out central air and an electric clothes dryer (240v loads) - but they are too big of loads to run on that size of generator anyway. 

You would need a way to feed 120v to both legs of your breaker panel, if you wanted to go that direction. That is what I do. In fact, I go further than that. I have set up a whole temporary power system with cabling etc that will allow a total stand-alone power solution or panel feed from any generator. The 3 gen outlets I have/use are 5-20R, L14-30R, and 14-50R. The latter 2 are 4 pin/dual voltage 120/240. My "main cables" are 4 conductor 6 gauge SER cable (aluminum) rated to 50 amps. Then on either end I can adapt any way I need to. What is very nice about this is, for example, house back up - the primary gen is the 15kw. It would only be a couple minutes to switch between any of my 3 units. So if I break the 15kw for an oil change I can toss in my 2600w rotary (L14-30 outlet). Or if we loose natural gas and I have to go to gasoline I can toss in my EU2200i inverter (5-20 outlet). Swapping gens is as easy as hooking up an extension cord. As for load management - that is all manual. Only essential loads can run on the smaller gens (no AC's and if someone wants to use a microwave oven we have to trim as much off for that time as possible). 

I am a firm believer that the 3500-4500w class generators are the "sweet spot" for efficient home back up. The EU2200i we have will run all essential loads. However, if we had that next larger size in to the 3500-4500w range we could have a huge leg up on the need for load scrutinizing. It would give us the ability to run a microwave on top of the "normal" essential loads without too much trouble/work. Below that 3500-4500w range you're really scrutinizing. 

Truth told, also - home back up was not why I got the EU2200i. The reason for it is it is my grab-and-go gen that has largely replaced my power inverter I used to hook to my truck batteries. It is also a fantastic quiet generator for camping and other outdoor events. To that point - I wouldn't want a larger unit for 90% of what I use the EU2200i for, but that other 10% is home back up where it would make a giant difference having the extra 1500-2000w. For that reason - unless you truly want suitcase style carry-about portable power I wouldn't go any smaller than a 3500w unit. You will cover a lot more bases with that next size family of units in the 3500-4500w class. These are commonly marketed to the RV crowd, by the way (not all 30 amp connectors are compatible so be careful with the connector styles). There are also a lot of them that, as you've found, are dual fuel from the factory. Big bonus.


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## iowagold (Jan 22, 2020)

yea the eu2200i gen sure is handy power for sure!
add on a tri fuel kit...
yup they work for us here!
i use up to 4 of them here..
pm if you need the power inlet setup for them!
i have pix and part numbers.
a nice project for sure.

the cool thing is 90% of the time i can get by with one eu2200i gen set!
saves fuel!


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## Gen10K (Jun 25, 2020)

I run a 8.5KW, 10 KW peak and runs fine on NG. The caveat is what is mentioned before. Due to the fact of the Low BTUs on NG the Gen will run at about 20% less on power output. I was able to run my AC and Washing Machine and all other appliances. That is pushing the Gen hard, burned the Gen Head because the engine could not keep up with the power demand; lesson learned.

On my case, 8.5K on Gasoline, 6.5KW on LPG and 4.5~5ish KW on NG.

The advantage is that NG is cheap, burns clean, is on tap and no shelf life. LPG the same as NG but with higher BTUs and cost a bit more and needs refilling. Gasoline, lower shelf life and need refill, but has the highest BTUs and burns dirtier. I can run mine on NG as long the service is up and use my LPG as backup and for cooking as well. Gasoline took a back seat for the Gen beause of convinience.

I think a 4KW on NG will do OK because has a smaller engine. Mine is a 16 HP and can keep up but less torque because of less BTUs, so struggle to bump the KWs past the 5ish KW mark.


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## Tboney (Sep 9, 2020)

Gen10K said:


> I run a 8.5KW, 10 KW peak and runs fine on NG. The caveat is what is mentioned before. Due to the fact of the Low BTUs on NG the Gen will run at about 20% less on power output. I was able to run my AC and Washing Machine and all other appliances. That is pushing the Gen hard, burned the Gen Head because the engine could not keep up with the power demand; lesson learned.
> 
> On my case, 8.5K on Gasoline, 6.5KW on LPG and 4.5~5ish KW on NG.
> 
> ...


I found out yesterday that the Champion generator I ordered has been backordered at least till the 1st of September. Thankfully the tropical storms are not headed our way.


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