Wrong LPG pipe size installed

[pr3dict]

Hi guys,

So I had a 500 gallon LPG installed the other day for a 22kw Generator and I was going over the startup procedures in the manual and came across a chart that basically said I need a 1" gas pipe. Well they installed a 3/4" pipe. Apparently this isnt going to cut it for how much BTUs to run the full 22kw.

Anyone have experience dealing with a company after they already ran a gas line? The work order said they were putting in a 3/4" but @ 15 feet but based on some changes that needed to be made they installed the tank ~35' away from the generator...

 

[The Cobbler]

It may be possible to run a 2 stage regulator, higher line pressure and reduced at the generator

 

[Milton Shaw]

Two regulator setup for 2 PSI line pressure to the second regulator at the Generator. That is what my system is. The actual line from the tank to the first regulator on the tank itself is only a 1/4" line like you would use for an icemaker. This is for a 17kw generator. The gas company should change/fix that for you and should not need a 1" line at all.

 

[pr3dict]

There is definitely not a 2nd stage regulator from what I can tell. It has a regulator at the tank and then goes to this 3/4" black hose which then goes down to a yellow 3/4" plastic pipe. Comes out of the ground with the same black 3/4" black hose and then into a shutoff valve. Then to some black (iron?) pipe then the generator.

I need 355,000 BTUs. What you are proposing can be done with 3/4" pipe?

 

[The Cobbler]

if you had a 2 stage regulator, the primary at the tank feeding the 3/4" at 2(ish)psi, then the secondary regulator at the generator to reduce the 2 psi to 11" water column, or whatever your generator asks for, the 3/4 would be usable .

 

[The Cobbler]

first stage regulator example https://propanewarehouse.com/shop/p...tors/10000-btu-compact-first-stage-regulator/
second stage example https://propanewarehouse.com/shop/p...regulators/500000-btu-second-stage-regulator/

 

[pr3dict]

See attached" no regulator

 

[Busted Knucles]

Crank it and try it. Should be fine

 

[rlitman]

Crank it and try it. Should be fine

I wouldn't accept a generator tested that just cranks and idles. It needs a load (preferably a load bank) to know if the gas flow is sufficient.

Back to the OP's charts, are those charts and pipe sizes referencing natural gas or LP specifically? NG need much larger pipes, but since you've got LP, 3/4" might actually be fine.

Alternatively, it might be acceptable to turn up the regulator at the tank. Will this LP tank be serving anything else?

For the record, ALL LP generators have a regulator. They require a "demand" regulator. It's a special regulator that allows the carburetor to ingest the LP without LP leaking when the engine is off. Demand regulators will have a range of acceptable inlet pressures, and assuming (not that it's safe to "assume" anything with LP) you're not serving anything else out of that tank, you could turn up the regulator at the tank to the upper end of the acceptable limits of your generator's demand regulator. If that doesn't provide sufficient flow, you could add the secondary regulator at the generator end of the pipe as described above.

 

[brewchief]

Make sure any chart you are looking at is for the PE pipe, ratings will be different for black,PE, copper, etc.

At 35' it looks like you are right there on a chart for PE pipe, remember also that that chart is based on a .5" pressure drop, most of the time you can handle a touch more drop.

Sent from my SM-T510 using Tapatalk

 

[pr3dict]

I was basing my numbers off that chart. It says that I need 355, 000BTUs and unless I'm less then 20 ft 3/4" is in the 200s

 

[pr3dict]

It seems they might have stepped down at the tank possibly to 10water whatever its called. Which instead they need to install another regulator at the generator so in the pipe they can do 2psi

 

[firebirdparts]

Really, they need to install a bigger line. Running the line at higher pressure is just a way to get the existing line to work, now that it's wrong.

 

[kj_mustang]

Not wrong, I have an 1000 gal tank suppling three different locations. All three have second stage regulators to get the proper pressure. I am pretty sure my main line from the tank is 1" plastic but the branch to the generator spot I think was smaller so probably 3/4".

 

[jonshonda]

Question 1) Did you provide them with the generator documentation so they understood the requirements?

Question 2) Have you asked them what their thoughts are?

 

[SethB]

Hi guys,

So I had a 500 gallon LPG installed the other day for a 22kw Generator and I was going over the startup procedures in the manual and came across a chart that basically said I need a 1" gas pipe. Well they installed a 3/4" pipe. Apparently this isnt going to cut it for how much BTUs to run the full 22kw.

Anyone have experience dealing with a company after they already ran a gas line? The work order said they were putting in a 3/4" but @ 15 feet but based on some changes that needed to be made they installed the tank ~35' away from the generator...

Which model of 22KW? for air cooled Generac, 3/4" is good to 40'

That chart is for vapor, you should be using LP gas

 

[yeldogt]

What else is on the tank?


Normally you have a primary regulator at the tank (often red) very small copper tube to the regulator from the tank. From this primary .... 3/4 out to various locations. At each location there is another secondary regulator.

If a miscalculation was made ... it's an easy fix. Take a picture of the tank outlet/ regulator setup that is there now.

 

[matt_i]

Is 35' of 1" dia black iron pipe + various fittings less costly than a higher pressure regulator?

I don't know for sure but it seems like that would not be the case.

 

[TractorJeff]

See attached" no regulator

In the photo provided, I see 3 elbows, they need to be factored in to the equation.
I would go back to the Installers to see if they will make it right.

 

[BD1]

Check gas valve tag on generator for maximum pressure inlet rating . It should be a LP tagged valve .
Check existing regulator tag for pressure ratings. It should say maximum inlet pressure.
Normally a test tee is installed after high pressure regulator to verify gas pressure.
This will tell you what pressure is.
Gas pipe size is based on pressure, footage, and BTU's. You can have smaller pipe with greater pressure and larger pipe with low pressure.
Contact gas supplier to see what regulator they installed and what maximum pressure rating is on gas valve.


Sent from my iPhone using Tapatalk

 

[dcg9381]

It's gonna run fine initially.. Fully loaded - that's the question.
Depends on what the contract said and what info you provided them.
Who asked to move it from 15' to 35'?
And my other question would be - if the generator line is undersized, isn't it on a "T" with the house? It'd leave the house undersized too..

 

[Adk Mike]

Won’t run the way it’s hooked up. A 22 KW generator is 374,000 BTU’s. You need a 2d stage regulator piped in next to the generator. And then vented away. Because it’s within 10 feet. Add a first stage at the tank. Piping is fine.

 

[BigDogSS]

Was the generator and installation purchased from the same vendor?

 

[pr3dict]

Lots of questions I'll try to answer them all.

Based on what I see they did a twin stage regulator because they originally designed the system for 15 feet to bring it down to 10-12in. WC.

The original plans of 15 feet were estimated before the building was built. After accounting for down a few feet into the ground and back up and not going in a straight line it ended up being roughly around 35-40' of pipe.

The 500 gallon tank is solely for the generator.

BTU's required based on the Spec sheet and manual is 355,000 BTU's @ full load.

The inlet pressure should be between 10-12in. WC.

A 3/4" PE pipe cannot give 355,000 BTU's @ 40ft with only 10-12in. WC.
A 3/4" PE pipe @ 2PSI sure as hell can. But requires a second stage regulator.

Generator was purchased from Home Depot and I installed it (Moved it where it needed to go and installed the electricity.) Propane company installed the LPG pipe and tank.

See attachments for reference. I dunno why the images wont show up but here is the link to the album. https://imgur.com/a/ha4cmpa

 

[The Cobbler]

Really, they need to install a bigger line. Running the line at higher pressure is just a way to get the existing line to work, now that it's wrong.

not anything wrong with it . 2 stage set ups are very common.

 

[BD1]

It'll be fine, pipe too small, run and see.
First you need to verify incoming pressure.
If that's a typical gas valve on generator,max pres is 14" . It should say on it. Running 1 pound or more it will ruin gas valve. One pound is 28"


Sent from my iPhone using Tapatalk

 

[MoonRise]

Do NOT try and fire up the generator yet!

Your chart shown on Post#11 clearly shows that you NEED 1" pipe for your ~50' pipe run (3 elbows plus a valve shown is 2.5' effective length added per elbow or fitting just in the pipe run to the generator adds 10' effective added length to the pipe length itself, plus whatever fittings are over at the tank end of the pipe run) for the 22kw generator.

Per you chart, the 3/4" pipe is only good for a total of 15 effective feet of piping length (including 2.5' of added effective length PER elbow or T or valve).

You've probably got ~15' of EFFECTIVE 3/4" pipe length right there just at the generator itself with the three elbows and the valve plus the pipe just from the ground and up-n-over to the generator.

Unless you told the propane company to install 3/4" pipe, they messed up the install.

They need to remove the 3/4" pipe and install 1" pipe OR they need to rig up a two-stage regulator system (a 'high pressure' ~2-3 psi regulator at the tank and then a low-pressure 12" WC regulator at the generator itself).

If your local CODE even allows the 'high-pressure' distribution line coming off the LPG tank before dropping down to the WC level device pressure.

But as it stands right now, that pipe run is No F'ing Good for that generator.

 

[Lassen Forge]

Part of the reason they require a 1" line instead of just upping the pressure on a 3/4" line has to do with the bernoulli principle - the same thing that allows your air conditioner and freezer to work. While the odds are against drawing a slug of re-condensed LPG into your generator, you REALLY don't want to do that. OR freeze your regulator. That could kinda **** as well... While you may NOT pull 22KW most of the time, the one time you do you want your system to handle it.

It's only 35 feet - pull the line and put in the correct size.

 

[pr3dict]

The propane company was kinda "The tech knows best and I have a little handy dandy booklet that says you'll be fine." I had to explain to them that science and math says otherwise and thats when they said they would send a tech to fix it next week.

I've had a few issues with this company already. They originally quoted me a 500 gallon tank and then the day of install showed up with 4 400lb (100 gallon) tanks. I was like NOPE especially after they had me dig my own trench and I busted my *** digging in the rock infested wasteland of New Jersey that I live in where if I knew they were doing 4 400lb tanks I could have just installed the tanks next to the garage... They caved and got me a 500 gallon tank but it was annoying.

Now this... The line is kind of half buried already. I didn't fill in the entire system thankfully but there are a few spots that would need to be dug out again which is a PITA if they are laying 1" pipe.

 

[ace10]

Did the name of the installing company rhyme with "Schmerigas" by any chance?

 

[pr3dict]

Did the name of the installing company rhyme with "Schmerigas" by any chance?

Nope it rhymes with "Suburban"

 

[jhelrey]

No drop T either at the appliance.

 

[jade97]

I'll have to check out my setup. I have a General 38kw. I know the line from the first regulator (at the tank) to the second regulator (more than 50' run) is no more than 1/2". From the 2nd regulator to the generator has a 2-4' section of 2" pipe that goes I to a flex line at the generator input.

 

[yeldogt]

It's common to run 3/4 distribution piping ....

My new 1000g tank has the primary regulator under the tank lid. Propane company made a manifold with two valves under tank lid from primary regulator. Each valve supplies a 3/4 line out. One goes to my generator about 25 feet away and the other goes to my studio with another split/ valve to my house. Each location has a second regulator. Generator/studio/house.

Call them up and tell them the guy did not calculate correctly -- they need to switch out the tank regulator and provide a secondary at the generator. Valve before the regulator -- you need a drip leg ..... is that a flex in the picture? You need one to isolate the generator piping.


Mine are all galvanized ...

 

[jade97]

I looked at the invoice...I have 1/2" copper from the 1st reg (@ tank) to the 2nd reg (Mounted to the house).

There is a drip line in the 2" galvanized.

I will try to post a photo.

 

[jade97]

------ Didn't work ------

 

[pr3dict]

Lol can you post a photo? The guy that was putting the pipe together at the generator was like his first day. The experienced guy left him alone because he had to go back and get the 500 gallon tank. This guy looked like it was his first time seeing leggos didnt know how to put it together.

There is a flexline that came with the generac. Whats the drip thing for?

 

[dcg9381]

The propane company was kinda "The tech knows best and I have a little handy dandy booklet that says you'll be fine." I had to explain to them that science and math says otherwise and thats when they said they would send a tech to fix it next week.

Then it's on them then. You should have a spec to that generator which says 1" on 35'...

 

[jade97]

From google:
Drip leg” and “sediment trap” are often used interchangeably, but they are really two different things. Drip legs (technically call just a “drip”) are installed to collect condensation in a gas piping system, so they are installed in a low point to prevent condensation from running back into the gas meter.

pr3dict, check your PMs.

 

[pr3dict]

Damn thats a big generator you got there.