This hurricane has me thinking about getting a whole-house generator. Like a 22kw type model.

Had an electrician come out to quote me an install, but the prices I’m getting seem very high. I feel pretty confident I can diy it, as it’s something I can buy on amazon.

Anyway, as far as the gas piping goes, right now I have 3/4” coming out of my meter located less than 10’ from where the generator would be installed. One electrician said something I thought was strange - to t-off of that 3/4” pipe with 1” pipe out to the generator for better gas flow. I’m used to seeing water distribution pipes which always go from larger diameter to smaller diameter.

So 2 questions for you all: would you just run 3/4” out to the unit, or install a larger pipe? I believe the inlet on these generators is only 3/4” anyway. Distance no more than 10’ for the branch.

Also, anyone have any tips on generator installs?

Thanks

Gas piping is different - you need proper size pipe for all your appliances based on BTU's and volume of gas in addition to PSI from the meter. You can figure it all out with the charts in the fuel gas code book for your state

[codes.iccsafe.org]

You also need to consider the electrical side though which is a whole nother animal - wire/breaker sizes and properly hooking up ATS so you dont fry a poor guy on the pole down the street.....22kw seems like way overkill to me unless you have like a 6,500 sq ft house.....

I could be wrong, but I would probably sub this one out....you can watch if you want to learn something but theres alot more to it than you think...

IMO i would go with diesel or propane separate from NG to the house, in real bad storms sometimes the gas company will kill the supply to avoid blowing up houses

also, 3 quote minimum for projects



Edited 2 times.

20 KW is about the minimum size they use around here.
they plan on running their heating system, a couple of refrigerators, computers, coffee makers and microwave oven as well as their lights..
the 20 KW needs to be at least 1 inch.
you have to check with your gas company to tell them what you plan to do..
gotta make sure they have enough gas on the street to supply that generator.
the gas company can increase the pressure at your meter if they think you need more gas.
remember, a bigger gas pipe acts like a storage tank. it takes more to draw it down.
i have even piped a couple of generators with 1 1/4 pipe.
a word of caution.
be aware of any noise ordinances in you town. i had to relocate a generator because it was placed too close to a neighbors house and it made a few decibels of noise above the limit.
lastly, if you can find a local electrician who sells generators you might get a pretty good package deal on the generator, parts and labor. plus you have someone local to stand behind the unit.

I agree with everything said. You need to know the specific gas requirements of the unit. Everything gets sized to the new load…….the meter, and all the branches. As said, the gas company has to have enough in the street. I've heard of times when a gas company was unable to provide enough gas. Generally it was an old neighborhood with only 1/2 pound available in the street(rare). The last thing you want to do is undersize the piping to a generator. They draw more gas when starting, and need to have a generous supply of gas. If it is starved for gas, you'll never get the rated output out of it.

Thanks for all the helpful comments. I will reach out to the gas company and inquire about the pressure available, etc.

Here’s a photo of the gas meter, located in my basement.

It appears to me that the pipe from the street (coming thru wall at bottom left) is 1” pipe. It then turns upward into a 3/4” pipe and into a pressure regulator of some sort, which has the vent pipe to the outside at left of photo. The pipe is 3/4” on both sides of the meter. The 3/4” pipe to the right of the meter runs at that size to my furnace, with a 1/2” branching off of it feeding my water heater.

At first glance, does the meter need to be changed out to something handling 1” pipes? I did check the generator install manual, they are calling for 1” pipe for the 22 kw unit.

i don't know what your gas supplier allows you (or a plumber) to work on.
they may send a crew out to change all that piping to one inch or they will allow you (or a plumber) to do the work ???
they might just change the meter bar (the piece with the silver tag on it) to a larger one ??
they are the supplier, it is their equipment, it is their gas so they make those decisions.
remember, they sell gas.. the more they sell, the more money they make.

The tag on the water meter should indicate its capacity in cfm. That will determine whether the meter has to be changed.

..... on the GAS meter .....



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Saying that the unit requires 1" pipe may or may not be accurate, depending on how everything is piped. You need to know the gas consumption under full load for the generator in cu/ft/hour. A cu/ft of natural gas is 1040 btus. You then add up the total btus of all the gas appliances in the house, and the meter is sized to that. [www.youtube.com]