Gas Plumbing into detached garage through breezeway.

[Mook Johnson]

before I get laughed at by a plumber I'd your opinion on if this is feasable.

I'm considering a 15KW NG generator that I would like to install behind my detached garage. My gas meter is on the side of the house opposite where the generator will be installed (of course).

I'm looking at "T"ing off the 1" ID gas pipe just as it enters the attic (1 story hose) about 10' from the meter. At that distance from the meter, that pipe is capable of supplying at least 550 CFH of NG. Down stream from the "T", the household appliances branch off and together consume a combined total of 200 CFH if everything is on (unlikely).

At the "T", I would run a second 1 1/2" ID line a total of 150 feet through the attic of the house, then through the attic if a 30' breezeway, and into the open frame detached garage. From the end of this 1 1/2", line the generator would consume 250CFH at full load.

1 1/2" pipe is likely overkill but was chosen to minimize the pressure drop while starting the generator. However there will be six 90 degre elbows in the pipe to make the trip so that would cause some flow restrictions.

This puts a load at the "T" in the attic at 450 CFH which is within what that diameter pipe is capable of supplying at 10' from the meter.

This of course will mean upgrading the meter to a larger one. my current model is rated for 250CFH@ 0.5" of H20 drop.

Questions.

1) This will be in Houston TX. Will ther ebe any code problems with running a gas pipe to the back of the garage in this manner?

I priced a second gas pipe and it is rediculous! $1500 to install and a minimum of $15 per month even if no gas is used.

2) Are there any technical issues with opening a 1" pipe up to 1 1/2" for along run with minimum drop?

3) any other problems with this approach? too many elbows?

thanks

[John Gilmer]

Were I you, I would "consider" getting a much smaller generator.

If you have NG in the first place, you are "close in" so power interruptions should not be all that frequent or prolonged.

All you NEED is enough power to keep the furnace working in winter (less than 1KW) and some nice to have stuff like lights and TV.

In summer you NEED the ice box, freezer, maybe a window A/C unit, and the TV.

15 KW is enough power to keep an "all electric" house going.

[hallerb]

Its probably cheaper to install the generator right near the gas line and run a main power cable to the breaker box. Easier than gas line. voltage drop on proper sized cable is meaningless..........

this houston poster doesnt want any inconvenience by a outage, I hope he opts for a autiomatic start system. Home depo is selling them locally/ You buy the generator and a contractor handles the entire install from concrete pad for generator to permits install and user training. You REALLY want a auto system it starts weekly for exercise and reports troubles automatically.

can you imagine having a big generator and finding it doesnt work when needed the most:(:(:(

I would love a neighbor like him he will have enough capacity to keep the neighbors fridges and such running. time for extension cords:)

[Speedy Jim]

John makes a very good point about the size.

Also (there was a recent thread about this), a meter changeout to larger rated capacity wil be *costly*. Look into that.

I don't see any problem with the way you want to run the line; maybe provision it that size no matter which genset you get. Be sure to include a large "drip leg" at the low end of the run thru the breezeway.

Is the elec service at the garage so that the required transfer switch will be easily wired in?

(assume all this work will be under permit??)

Jim

[John Gilmer]

The last time our power went out for an extended period of time (more than

24 hours), we saw an extension cord strung out over the public highway. I think they had public power on one side of the road but down lines on the other side. (We lose power a lot because wind takes broken trees into power lines.)

This was the first extended outage for us since getting a 5KW generator. Just enough for the water pump, a room air condition, light cooking on the stove, coffee pot, ice box.

Had it lasted longer I would have played games and heated up a batch of hot water for some quick showers but it wasn't necessary. The hot water heater draws 4400 watts. The generator likely could heat water and maybe run the TV at the same time.

We have some neighbors (on the rich side) who have a large generator that comes on automatically. When our lights fail, the sound of their generator tells us whether it's just our transformer or a larger outage.

>

[John Gilmer]

Maybe so; maybe no.

Running a gas pipe isn't much more trouble than running conduit. And once you have a gas line running through the house it becomes cheap to add in to taps for ventless gas room heaters.

With a 15KW unit, you almost certainly would have an automatic transfer switch and automatic exercising of the generator once a week/month. Thus, you have to provide for the control wiring as well as the power cable.

[Mook Johnson]

15KW is a given. I've looked at downsizing the generator to make life easier but it only makes the install easier and use more complicated. I didn't want to mess with a rollout A/C unit that will sit idle for months and infrequently called out to service (maintanance/mold?) and I didn't want to hang a window unit in a new home that has central air. My wife can't install a window unit on her own if I'm not there when the power goes out.

I'm OK with buying a $3500 generator but I don't think it costs an extra $5000 to install it correctly. Thats the amount of the quotes I've been getting.

install genny, pour clab (or crushed rock bed :(), wire into house, test and demo.

$5000 please.

I'm looking hire a plumber to do the gas run and I can get the slab, grounding spike and electrical hookup installed to code with permits myself (Electrical work by trade).

I just wanted to make sure there was not problem with going from a 1" gas pipe to a 1.5" pipe to make a long run with minimum drop. And if anyone know of plumbing code preventing running gas pipe through a breezeway attic into a detached garage.

[Mook Johnson]

I looked into that as well but the wire would have to be #4 awg to get to the garage with minimum voltage drop (~5volts). I'll also have to deal ith conduit through a few 0 degree turns. It would be really combersom to handle. A pipe would be no problem since these are straight lines.

This house was wired whacky and the fuse box is the farest it can possibly be from the A/C unit. The genny would be near the A/C unit (largest consumer) and the power would have to flow across the house into the garage (~150 feet of length or 300 feet of loop length) then back all the way across the garage an house to the A/C unit.

Plus that puts it near the master bedroom. Don't want all that noise a wall away. Behind the garage faces woods so the neighbors noise gets dissipated.

Home Depot had a sale on for 250 off on the generator and another 200 off if you use the HD credit card. I was going to pay cash but hey I'll route it through their card if there giving away 200 bucks.

[Mook Johnson]

You Guardian 15kW with 16 circuits transfer swith/sub panel. Not the whole house but plenty enough to keep the A/C going.

[Mook Johnson]

Yes all work will have a permitt and done to code. I will make sure to ask the plumber about the dripleg and centerpoint about the larger meter.

thanks.

[alexb]

In reading these post I haven't seen any comment about the 1" gas pipe being opened up to 1.5". Boyles Law states that this will reduce your gas pressure 66%. In other words you will not get any more volume out of a 1" pipe by upsizing to 1.5" you'll just be reducing the pressure in the line. Residential NG service is already low pressure so I would talk with a plumber before you take the time to run all of this pipe only to discover you now don't have the pressure to run the generator.

I hope this helps.

[wcs94]

Boyles Law only applies to closed systems.

[alexb]

I sure this is a dead topic by now, but that wasn't really the point. Yes, I agree Boyle's Law applies to closed systems. However, pressurized gas plumbing systems behave in a similiar manner with regard to pressure/volume relationships. That is why it's referenced in the National Fuel Gas Code. My point was simply that piping doesn't go from little to big as it approaches the point of use. The 1" Gas pipe in the attic referenced above will not deliver more volume to the generator if the branch line is run in 1.5". If that were the case cities could save a bunch of money by running 1/2" gas mains under the streets and then just upsizing at the meters. I was only trying to help the poster avoid the expense and difficulty of installing the 1.5" pipe as opposed to just running the branch to the generator in 1". I know everyone on the Internet is an expert, that's why I also suggested asking a local gas plumber if I'm full of it.