Generator Question

[Rat Rod Mac]

I don't know if this is the place for this question or not. If not maybe someone could direct me to the proper place. I am serious thinking about installing a 3500 watt generator for emergency purposes only and since the farm has free gas was thinking about the generators that can run off of natural gas. Here is my main question,,, the gas line in the house is a 3/4" pipe and the gas pressure in the house is 7 ounces. I have run a line to the outside of the house where I will hook up my generator when the power goes off, but is 7 ounces enough to run the generator? If it is, is it also enough to run the furnace and possibly the stove at the same time? Has anyone out there done this before? Also, are there some generators better suited for this gas than others? I know Honda has a generator that can be made to run on natural gas. Anyone know if one make is better than another. Thanks in advance for all of your help. and responses. It is very much appreciated. RRM

 

[daveshoot]

I have excellent results with a 10 kW Generac running on propane. It is pretty quiet and never fails to start (runs a test cycle once per week automatically).

However, I have no other insight on your specific question re:gas pressure or natural gas in general.

 

[V1Rotate]

It is not so much the pressure of the gas that is important but the volume, 7 inches of pressure is the standard for natural gas.
I have gas heat and when I installed a standby generator I had to get a larger gas meter installed. My gas meter was rated for 250,000 BTU which was fine for my 175,000 BTU furnace but was not large enough to also supply the 10 KW generator. So I called the gas company and had them install a larger capacity meter, which they did free of charge.

 

[nikdfish]

I am not a natural gas expert by any stretch of the imagination, but I've seen a few descriptions of some of the issues involved.

I think the ballpark figure for natural gas running an IC motor is something like 10 CFH (cubic feet per hour) per horse. Multiply that by the horsepower of the generator when running natural gas & see the amount required.

The size of the pipe delivering the gas needs to be sized based on the length of the run. Longer runs need larger pipe to deliver a given quantity of gas. For example, a 3/4" pipe 90 feet long can deliver about 111 CFH while a 30' 3/4" pipe can deliver 200 CFH. You would need to calculate the total load for your home based on consumption, then look at the supply lines to see how large they need to be for a given run to deliver the needed volume of gas.

I think you'd be well served to consult with a natural gas systems guy to see if your current setup can support what you want to do.

You can see a discussion of the installation issues here: Natural Gas Generator Pipe Size Chart

Nick

 

[Toyboy]

I had a 20kw installed running NG and the gas company had to change my meter to higher volume?....whatever...they told me that the one I was using would not support the house & gen at the same time. Changed it out for free. You have to get a regulator for your gen similar to the kind they use for propane. It was adjusted to what the gen called for.
In short, contact your gas co.

 

[Wagtail]

Not having gas on my property, my question would be if the generator is tied into a supply grid, what happens to your supply if the grid shuts down?

If there's a bush fire, the utility companys standardly shut down power & gas to the area. If you (assuming you live in a very cold climate area) lose power & the gas due to freezing rain, again you're stuffed.

A generator needs to be 'stand alone' to properly do the job you need it for, doesn't it? :confused3:

 

[Larry Caldwell]

I am not a natural gas expert by any stretch of the imagination, but I've seen a few descriptions of some of the issues involved.

I think the ballpark figure for natural gas running an IC motor is something like 10 CFH (cubic feet per hour) per horse. Multiply that by the horsepower of the generator when running natural gas & see the amount required.

The size of the pipe delivering the gas needs to be sized based on the length of the run. Longer runs need larger pipe to deliver a given quantity of gas. For example, a 3/4" pipe 90 feet long can deliver about 111 CFH while a 30' 3/4" pipe can deliver 200 CFH. You would need to calculate the total load for your home based on consumption, then look at the supply lines to see how large they need to be for a given run to deliver the needed volume of gas.

I think you'd be well served to consult with a natural gas systems guy to see if your current setup can support what you want to do.

You can see a discussion of the installation issues here: Natural Gas Generator Pipe Size Chart

Nick

What he said. Your problem is most likely going to be the size of the pipe, or the size of the regulator orifice that feeds the pipe. Locating the generator closer to the regulator might be a good solution, both for reducing the pipe run and reducing the engine noise at the house. If your 3500 watt generator is 240v, 12 gauge wire will get you 100' with no problem. That's only 14 amps. At 120v, it's 28 amps and you would need 10 gauge wire, and 8 gauge would be better. Is it cheaper to dig up the gas line and replace it, or bury an electrical feed line?

Whatever you do, it will likely cost you quite a bit of money. That's the price tag on "free." You didn't mention what your definition of "emergency" is. If you need electricity to run the furnace at 20 below zero, that justifies a pretty expensive natural gas emergency system. If you just need to keep the freezer cold and watch TV, a $150 camp generator and a couple cans of unleaded will do what you need.

 

[Rat Rod Mac]

Gentlemen, thank you all for your concerns and suggestions. You have given me food for thought and plenty to think about. Thanks. RRM

 

[cattoon]

If I may ask, how do you have free gas? I would consider a 20 kW gen set and turn off the breaker for line power LOL

 

[Midniteoyl]

Not having gas on my property, my question would be if the generator is tied into a supply grid, what happens to your supply if the grid shuts down?

If there's a bush fire, the utility companys standardly shut down power & gas to the area. If you (assuming you live in a very cold climate area) lose power & the gas due to freezing rain, again you're stuffed.

A generator needs to be 'stand alone' to properly do the job you need it for, doesn't it? :confused3:

Gas companies run gensets to supply gas in case of power outage.. They can go for weeks or months.