My house is under construction and the plumber just installed the LPG gas
lines. I am suspicious that he might not have this right.
I have a buried gas tank which is not yet connected to the house. It will
be supplying a furnace, a cook-top, a fireplace and a tank-less water
heater. The plumber split the input into two lines just outside the house
with one line going to the water heater and the other line going to a
manifold that splits off to the furnace, cook-top, and fireplace. These
are all done with flex line (except the manifold and the pipes at entry to
the house and to the water heater).
The cook-top specifies minimum 5/8 inch flex line supply and the plumber
has used 3/4 inch from the manifold to the cook-top (about 30 feet).
That's good, but he only has 1/2 inch from the tank to the manifold
(about 15 feet). Seems like this is insufficient for the cook-top alone,
much less the furnace and fireplace as well.
I plan on asking the plumber for details on how he established these line
sizes and contacting the gas company to see if they will inspect the
Am I seeing this correctly? Any suggestions?
First a disclaimer, I know nothing, myself, about LPG. That said, if it was
me, besides asking in the Newsgroup, as you have done, I would contact the
manufacturer of the equipment (furnace and cook top) as well as talking to a
representative of the local Natural Gas company, if there is one. It's true
Natural Gas and Propane does not use the same orifice size but given
pressure of the gas and the fact it's gas I'm guessing that the delivery
system (i.e. Size of pipes and procedure) would be the same. That way if
there is any local codes you might gain knowledge about them also.
On 12/24/06 8:58 AM, in article firstname.lastname@example.org,
You might take a look at http://www.missiongas.com/underground-tanks.htm to assure buried standards are met as well as supply standards. Your area of residence 'should' have a written set of standards for compliance with NFPA. The best source should be your local LPG dealer. Also take a look at
for locating/placing ASME containers. While Mission Gas is located in Texas, I believe all states conform to the NFPA standards. Your local LPG supplier will probably refuse to fill or service your residence if compliance is not met/demonstrated for burial but would undoubtedly service you if the supply line is inadequately sized. In essence, that's not his problem.
On an additional note, the feed lines/trench from the tank to the house have burial marking standards as well. IE: Bedding/wrapping/cathodic protection/marking tape above the piping.
face=Arial size=2>...</FONT></DIV><FONT face=Arial size=2>> Hello,<BR>>
<BR>> My house is under construction and the plumber just installed the LPG gas<BR>> lines. I am suspicious that he might not have this right.<BR>> <BR>> I have a buried gas tank which is not yet connected to the house. It will<BR>> be supplying a furnace, a cook-top, a fireplace and a tank-less water<BR>> heater. The plumber split the input into two lines just outside
the house<BR>> with one line going to the water heater and the other line
going to a<BR>> manifold that splits off to the furnace, cook-top, and
fireplace. These<BR>> are all done with flex line (except the manifold and
the pipes at entry to<BR>> the house and to the water heater).<BR>>
<BR>> The cook-top specifies minimum 5/8 inch flex line supply and the plumber<BR>> has used 3/4 inch from the manifold to the cook-top (about 30 feet).<BR>> That's good, but he only has 1/2 inch from the tank to the manifold<BR>> (about 15 feet). Seems like this is insufficient for the
cook-top alone,<BR>> much less the furnace and fireplace as well.<BR>>
<BR>> I plan on asking the plumber for details on how he established these line<BR>> sizes and contacting the gas company to see if they will inspect the<BR>> installation.<BR>> <BR>> Am I seeing this correctly? Any suggestions?<BR>> <BR>> Thanks,<BR>> Bob</FONT></BODY></HTML>
On Sun, 24 Dec 2006 11:22:44 -0800, Dan Deckert wrote:
Thanks for the links and info. I think I am OK with the buried tank. I
wioll double-check but I believe the people who installed the tank are my
propane suppliers. I did notice that the tank was backfilled with the same
masonry sand used to put up the stonework on my house (as reccommended by
one of those web pages). The tank is also situated in a way to meet all
the guidelines on the other web page.
As I said, I plan on asking the LPG supplier to inspect the whole thing.
If they won't do that perhaps they can recommend someone who will.
You didn't say what pressure. Here we have 1/2 pound or 2 pound systems.
For a 2 pound system those sizes are plenty big enough. For a 1/2 pound
system I think the 1/2" to the manifold might ought to be 3/4". Ask the
inspector what he thinks. Not just if it passes code but would he be
okay with it in his house.
I know nothing about LPG but i think it may be like this. The tank is under
pressure and the 1/2 line brings high pressure lpg to the manifold. The 3/4
line then distributes low pressure lpg to the appliaces. A small pipe at
high pressure will yeild the same as a large pipe at low pressure.
... [snip more on LPG installation to the nub of the question]...
The other poster noting high vs low pressure distribution _probably_
has the right idea.
Where's the regulator installed? That's the key as that controls the
high to low pressure transition point.
The LPG service company/supplier should, in fact, require that they
inspect the installation before beginning service. Around here,
anyway, that's part of the deal. If not included as a service, I'd ask
for it and pay the service fee before going on. This should, of
course, also include the leak/pressure test just as in a natural gas
LP is no more hazardous than natural gas, but no less, either...both
This I do not know right now. I can go check in a day or two. But, if the
regulator is at the manifold it would mean that the installation is using
flexpipe for high pressure and I don't think that is appropriate -- I
think I remember the flexpipe had "5 psi" written on it. Would that be low
LPG may be a little more hazardous. One difference is that it is heavier
than air where NG is lighter than air. This was told to me by the guy who
sells gas fireplace inserts. He said that is why LPG, but not NG, requires
a pilot light by code -- so gas does not accumulate. I think the idea is
that NG will tend to disperse but LPG will not.
On Sun, 24 Dec 2006 07:58:59 -0600, I wrote:
In response to my own post -- I found out that (believe it or not!) the
Texas Railroad Commission is responsible for inspecting LPG installations
and the gas company won't deliver until there is a "passed" sticker from
What I don't know is if thie is just a "safety" inspection or if it will
tel me if there is enough capacity to cover all my LPG needs.
I just installed a LPG vent free fireplace insert at my house.
Destructions called for 5/8 supply line which really didn't make mush
sense as it connects to a 3/8 flare fitting on the appliance. Not much
more than a 1/4 opening in the 3/8th flare.
Works great though, getting me through these hard cold florida winters.
Be there for the inspection and ask questions. Specifically "Was it done
right?" or "Would you be okay with this in your house?". Most inspectors
I have met are nice guys that don't mind telling you what they think.
Passing code and having a good job are two different things and every
inspector knows that.
I got a guy from the gas company to take a look. My worries were mostly
due to my own ignorance about how LPG installations work.
My 1/2 inch supply line os OK since it is in the "high pressure" (2 PSI)
section. This will get reduced to 6-8 ounces at the manifold with a
regulator; thus the smaller line (at high pressure) can adequately supply
the multiple lines leaving the manifold (at low pressure).
At entry to the house there will be a regulator reducing the pressure from
10 PSI to 2 PSI (to feed the manifold) and another regulator to get low
pressure to the hot water heater. The tank itself will have a regulator to
supply 10 PSI to the house.
The guy from the gas company did say he would do things a little
differently: He wouldn't split off the hot water heater at entry to the
house but instead run a line from the manifold back to the water heater,
eliminating the need for one of the regulators.
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