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loose nut
12-22-2012, 11:40 AM
Had the first storm of the winter last night, not much of one but we lost the power AGAINNNN!!!!!! I have had enough of power outages so it's time to get a generator. I don't need one of those fancy "turn on within so many seconds and will run the whole house type" a simple one will do. I would like to run it on natural gas thought.

How hard is it to convert on to run on natural gas. I haven't seen any locally that do and don't say get it off of e-bay 'cause homie don't do dat'.

lakeside53
12-22-2012, 11:57 AM
Simple. I have a "tri-fuel" generator. The simple way on mine is a riser block with gas jet between the carb and the inlet manifold, and a decent sized demand pressure regulator (you are feeding it with low pressure, so it's larger than you may expect). My 16hp motor regulator is about 8 inches diameter.


Running on natural gas will only give you about 60% of the hp (and kw output) that you'd get on gasoline, so plan accordingly. Also... mine says "you will not be able to hand start this generator on natural gas - use electic start". That's ok... I can't pull start the damn thing on gasoline anyhow!

1-800miner
12-22-2012, 01:08 PM
Your local propane company will be your go to guy.

danlb
12-22-2012, 01:12 PM
The other two 'gotchas' that I recall are:

1) make sure your gas service can provide the volume you need to run the generator.

2) I heard that low temperatures cause harder starting.


The electric start is needed because the regulator will let the gas flow only when there is a vacuum. Pull start will supply a vacuum intermittently.

Good luck with the install. I've seen conversion kits available onlne.

Dan

lbhsbz
12-22-2012, 01:51 PM
one other thing that I'm aware of but rarely see mentioned is the valves/valve seats. When using a liquid fuel, you get some cooling effect....with CNG or propane, you do not. The valve seat contact area is usually much larger on a CNG or propane engine than on a gasoline engine. The larger seat contact area helps get heat out of the valve....might not be necessary for intermittent use, but it will help in the long term with longevity.

wierdscience
12-22-2012, 01:54 PM
Here's one outfit that sells kits-

http://www.propanecarbs.com/tri_fuel_kits.html

Bill736
12-22-2012, 08:28 PM
Just to serve as a price guideline, my neighbor recently had a Generac 17 kW automatic standby LPG generator installed by the local gas company. The generator itself, complete with transfer switch, cost $3900, with free shipping. The final installed price , including a gravel generator pad and two 100 gal. LPG tanks, was right at $10,000. Some of that work you could do yourself, but some of it would probably have to be done and/or inspected by a professional. I think I'll just keep rolling out my portable generator and my little plywood " pup tent" weather cover. And, several 12 gauge extension cords.

sasquatch
12-22-2012, 09:02 PM
Check with "Bell Canada". Most all those Bell repair vans used to have nice "Onan" electric start, propane powered generators. And,, They were the 1800 RPM ones.
Not sure if they still do, but they used to sell these off after a few years when updating their vans/ equipment. LOTS of those generators only had a few hundred hours on them. Good units!

loose nut
12-23-2012, 10:32 AM
Just to serve as a price guideline, my neighbor recently had a Generac 17 kW automatic standby LPG generator installed by the local gas company. The generator itself, complete with transfer switch, cost $3900, with free shipping. The final installed price , including a gravel generator pad and two 100 gal. LPG tanks, was right at $10,000. Some of that work you could do yourself, but some of it would probably have to be done and/or inspected by a professional. I think I'll just keep rolling out my portable generator and my little plywood " pup tent" weather cover. And, several 12 gauge extension cords.

That's exactly what I don't want. I don't need to run the whole house like nothing has happened, I just need to be able to run the fan on the gas furnace, the fridge and a couple of lights. The power is usually on again in a couple of hours maybe a day or so in the extreme (major storm damage). I'm just getting to old to put up with freezing in the dark.

Bmyers
12-23-2012, 04:49 PM
That's exactly what I don't want. I don't need to run the whole house like nothing has happened, I just need to be able to run the fan on the gas furnace, the fridge and a couple of lights. The power is usually on again in a couple of hours maybe a day or so in the extreme (major storm damage). I'm just getting to old to put up with freezing in the dark.

I use a honda EU2000I to do just that. A gallon of gas lasts me a day or better if I only run the fridge occationally. I bought a small transfer switch to run the furnace, fridge, some lights and a recepticle in the basement I can alternate running the freeze and hotwater heater combustion system.

darryl
12-23-2012, 06:43 PM
Not too much of a hijack I hope- but a question- what kind of gas do people use in their generators? I've heard the stories about gasoline going bad, varnishing up the jets, etc. I've also heard horror stories about ethanol in gasoline, corroding parts, causing problems if it has sat for too long, etc. What's the deal on using premium only in these generators? Will the fuel be able to sit for long periods of time in the tank without causing problems, and can you use high test in a generator? What are the recommendations? I'm just thinking that perhaps a fuel with a long shelf life would be better than converting the engine to use propane or natural gas.

Alan Douglas
12-23-2012, 06:53 PM
I wouldn't store gas in the generator tank. I keep it in a sealed 5-gallon can. I know it's sealed because pressure builds up inside, so moisture can't get in. I've kept ordinary winter gasoline that way for a year and a half and it doesn't appear to change at all, no "varnish", no problems with the ethanol in it.

Since the (polyethylene) cans do build up pressure, I store them in an insulated box behind a detached shed.

lakeside53
12-23-2012, 07:40 PM
I use gas station gas, and around here it has ethanol in it. Good enough for fall though all winter (it's "cool"); come late spring it all all my stored gas (35 gallons) gets recycled though the truck.

I service generators. Varnish doesn't happen over night. Even with crappy brand gas, it takes a year or so. Be smart and keep your gas cycled though every few months. Drain the carb when you refresh the tank - either run it or use the bowl drain. Definitely drain the carb bowl for storage. Running it out of gas" won't typically get all the gas out of the bowl. Start the generator and run it with a load (heaters work fine) every month until hot.

You can use premium if you like. Wont hurt anything. If you're really concerned about fuel stability and long life, run avgas 100LL (not legal - still has lead). It will last "years".

danlb
12-23-2012, 10:48 PM
That's exactly what I don't want. I don't need to run the whole house like nothing has happened, I just need to be able to run the fan on the gas furnace, the fridge and a couple of lights. The power is usually on again in a couple of hours maybe a day or so in the extreme (major storm damage). I'm just getting to old to put up with freezing in the dark.

I'm not trying to change your mind, but I found that wiring a transfer switch in makes it super simple to use the generator. In my case I have the whole house on the generator but I only use the circuits that I want to use. A whole house manual transfer switch is a hundred bucks or so and install is only another hundred. It goes in line between the meter and the main panel. I got an auto transfer switch for $300. Circuit specific transfer switches can be cheaper but require more wiring to install.

Running extension cords to the furnace, fridge and a couple of lights is awkward.


Dan

Ohio Mike
12-23-2012, 11:20 PM
Not too much of a hijack I hope- but a question- what kind of gas do people use in their generators? I've heard the stories about gasoline going bad, varnishing up the jets, etc. I've also heard horror stories about ethanol in gasoline, corroding parts, causing problems if it has sat for too long, etc. What's the deal on using premium only in these generators? Will the fuel be able to sit for long periods of time in the tank without causing problems, and can you use high test in a generator? What are the recommendations? I'm just thinking that perhaps a fuel with a long shelf life would be better than converting the engine to use propane or natural gas.

I run normal 87 octane unlead from the normal discount retailers, mostly Kroger and Turkey Hill stations. Every gallon of gas that goes in one of my portable cans gets Sta-Bil added. I keep the generator full and ready to run. It gets started occasionally and the fuel tank is drained in the spring and that gas is dumped in the truck which burns it up within a day. I do run the carburetor out of gas by shutting off the fuel before stopping the motor allowing it to run down. My generator is powered by a Robin/Subaru engine which starts quickly and runs smooth. Whenever the generator is run (under load that is) I immediately change the oil as I never know if an outage will be a few hours or a few days. If it runs for a couple of days and needs to keep running then I change it again. Its pretty simple since it holds a quart. House circuits requiring backup are on a six circuit manual transfer switch and permanent receptacle is place outside near the meter base.

lakeside53
12-24-2012, 12:07 AM
I'm not trying to change your mind, but I found that wiring a transfer switch in makes it super simple to use the generator. In my case I have the whole house on the generator but I only use the circuits that I want to use. A whole house manual transfer switch is a hundred bucks or so and install is only another hundred. It goes in line between the meter and the main panel. I got an auto transfer switch for $300. Circuit specific transfer switches can be cheaper but require more wiring to install.

Running extension cords to the furnace, fridge and a couple of lights is awkward.


Dan


I've done both, much many more of the sub-panel transfer. Intercepting the main panel feeds requires pulling the meter and dealing with the heavy power feeds in a code compliant manner. Around here meters have seals and require the power company to break them, and an inspection to have them resealed.

Adding in a selected circuit panel does not require pulling the meter, and takes maybe 1/2 day, the whole day if you muck around, and is within the capabilities of many homeowners if they can follow relatively simple directions. One switch/breaker transfers the power to the generator feed circuits. So need to "load shed" the heavy circuits.

danlb
12-24-2012, 12:20 AM
I've done both, much many more of the sub-panel transfer. Intercepting the main panel feeds requires pulling the meter and dealing with the heavy power feeds in a code compliant manner. Around here meters have seals and require the power company to break them, and an inspection to have them resealed.



I can't speak for all installs, but in my case the heavy wire from the meter to the panel was cut, the transfer switch was inserted into the circuit and the job was done in an hour or so. A short jumper was required because both the input and output of the switch came through the bottom of the switch enclosure. If the output went out the top we would not have needed any wire other than the connection to the generator plug in.

It is a very good idea to make it code compliant in any event. While some of it seems silly, most of the code has good mechanical, electrical or safety reasons.

[edit] I just noticed that the meter may need to be pulled if there is no breaker at the meter. Mine had a breaker to kill all power from the meter to the inside wiring.

Dan

lakeside53
12-24-2012, 12:43 AM
Around here the main power is direct from the meter (no breaker) and enters either [near] the top or bottom of the panel in conduit, and often with aluminum conductors. Never mind the conduit issues (can't just "break") , but placing a switch above 69 (?) inches (i.e. above the panel) breaks code. Yes, I some cases it might be relatively easy, but in my experience, rarely, and probably not something an average homeowner should tackle without some oversight or experience. If you pay an electrician to do the work, it's going to get pretty expensive (at least here..).

sch
12-24-2012, 06:16 AM
Regarding the original question of natural gas, as one poster noted it is less energy efficient than propane and much less than gasoline powered, which in turn are less efficient than
diesel. The 60% derating for NG compared with gasoline is not far off. NG is ~10-15% less than propane. The carburetor change for NG is very simple and straight forward as mentioned and
the motor will run much more cleanly on NG but the engine needs to be rated appropriate to your load. If converting gasoline to NG, estimate your maximum load likely needed and then
divide the generator size by 0.6 to get an estimate of the needed size. Best to add a kilowatt or two. Compressors are surge loads (even fridges) and start up may bump the demand
50% over run amps, which can, if the generator is near max output really drop the voltage and frequency. HVAC on AC really put the whammy on generators as 3-5T units may demand
60-90amps surge with 25A run for the compressor: look on the spec plate for the HVAC, should be listed there. Heater much less demanding if NG, worse if heat pump.
NG CF/hour may be estimated by looking at Generac website and drilling down to the specs on generators and they will give some ranges of CF/hr. Gas meters have limits but in my
area a gas meter with a white face where the dials are is low output pressure and a red face indicates high output pressure. Generators of 5-10KW on NG will need in the 125-200 CF/hr. You will need a certified gas licensed person (plumber or HVAC) to run the line and an inspection by your local inspector and/or gas company. Depends on local practice and mores. Propane will need a large tank and similarly expensive
piping, plus refill will be dicey when you most need it. Generac has consumption rate charts for propane fueled generators as well. NG is preferrable if available.

A.K. Boomer
12-24-2012, 09:56 AM
one other thing that I'm aware of but rarely see mentioned is the valves/valve seats. When using a liquid fuel, you get some cooling effect....with CNG or propane, you do not. The valve seat contact area is usually much larger on a CNG or propane engine than on a gasoline engine. The larger seat contact area helps get heat out of the valve....might not be necessary for intermittent use, but it will help in the long term with longevity.

That's a good point - but generally generators are not running no where near full bore, and that coupled with Laksides statement that NG makes them about 60% of the normal output and youv got yourself a total slug that most likely won't be able to hurt itself, as long as the mixture is correct you generally have greater heat with greater demands - just saying only 60% of it's normal capabilities is a pretty good heat overload buffer.

semi-vaporized liquid fuel is a super-cooler for some internal combustion parts - primarily the intake valve and the top of the piston - exhaust valves not so much.

vpt
12-24-2012, 10:11 AM
Our family business has owned some bigger (barely portable even with wheels) generator for around 10 years now and I believe we used it once in a storm.

I picked up a eu2000 for charging the batteries while camping and have used this little inverter for a bunch of little projects "away from power". Very nice little units that are useful for more than just the once every 5 year storm. And hondas never lose their value.

http://img713.imageshack.us/img713/4051/undercoating008.jpg

ironmonger
12-24-2012, 02:39 PM
The advantage of natural gas or propane, if this is a one way conversion, is that it will yield equal horsepower if the compression ratio is raised. Both of those fuels are comfortable running in engines of 14 or 15 : 1 compression ratios. This will make up for the lower output if your engine can withstand the greater compression. Pretty easy to do in flat head engines as well.

Propane will keep for decades in a cylinder, natural gas is great as long as there is gas in the mains. My vote is for a natural gas/propane system.


paul



[QUOTE=sch;818096]Regarding the original question of natural gas, as one poster noted it is less energy efficient than propane and much less than gasoline powered, which in turn are less efficient than
diesel. The 60% derating for NG compared with gasoline is not far off. NG is ~10-15% less than propane. The carburetor change for NG is very simple and straight forward as mentioned and
the motor will run much more cleanly on NG but the engine needs to be rated appropriate to your load. If converting gasoline to NG, estimate your maximum load likely needed and then
<snip>

Abner
12-24-2012, 05:47 PM
Something to watch out for if it is large unit. The gas co. will charge you an extra fee for the intermittent capacity you will require. Runs $50.00 a month for a guy I know with a 40k system he hardly uses.

ironmonger
12-25-2012, 09:02 AM
Typical residential gas meter here in the Wisconsin area has a flow capacity of 425 cubic feet per hour. That is 425,000 BTU/Hour.
Knock off 100,000 BTU for a typical furnace, and 40,000 for a water heater and another 100,000 for a gas range ( that HIGH) and that leaves about 135,000 BTU/Hour.
That is the equivalent of over 50 horsepower, over 39 KW electrical.
<Forgot the IC losses the first go-round>
Minus the loss in an IC engine, more like 15 hp 12KW. If you can live without the gas range you can add about another 11 hp or 8 kw for about 20kw.
The whole point is why would they sock you for extra draw up to the max the meter can deliver. Even if they do, the propane is going to be there regardless of the emergency.


See:
http://converters360.com/power/btu-per-hour-to-horsepower-conversion.htm


The OP seems to want power for his home. If he is considering converting to natural gas I have to assume that he has gas heat... 40 kw is a massive amount of power capacity for a home.

paul




Something to watch out for if it is large unit. The gas co. will charge you an extra fee for the intermittent capacity you will require. Runs $50.00 a month for a guy I know with a 40k system he hardly uses.

A.K. Boomer
12-25-2012, 09:39 AM
Something to watch out for if it is large unit. The gas co. will charge you an extra fee for the intermittent capacity you will require. Runs $50.00 a month for a guy I know with a 40k system he hardly uses.

Holy man - yes well worth bringing up.

and do wonder why so many people resort to massive overkill with emergency systems - I mean - it should be just for the bare essentials, keep the food from going bad in the fringe and freezer - supply enough power to run your furnace fan so you don't freeze pipes and freeze to death and run a few lights.

if you have enough power to do this then you can actually do everything else if you alternate tasks.

course - if you have electric heat your screwed and need a massive back-up - of course - if youv got electric heat your already screwed even if the power remains on.

loose nut
12-25-2012, 10:34 AM
I'm not looking to power the whole house, just the opposite. I need power to run the gas furnace blower, they don't work without it, the fridge and a couple of lights.

That's all.

I figure about 4K max. to allow for some peak loading IE: fridge compressor staring etc. It would be nice to be able to run it on Natural gas because the fuel storage problem is gone.

Abner
12-25-2012, 10:39 AM
Sorry, it is a nursery operation, and yes 40 kw is overkill for a household.
I run a Onan 15 kw on the back of a 21 hp Kubota under household (+) use. I also have a 40 HP Caterpillar for heavy use.
Watch out for any automatic motor starting loads such as well pumps. I picked up mine for $1,100.00 - already had the tractor.