A sediment trap is a short piece of gas pipe installed near an appliance that helps to collect debris in the gas line.  The idea is that any debris in the gas line will collect in the sediment trap before that debris can foul up the appliance’s gas valve and cause trouble.

You’ll often hear the term “drip leg” instead of sediment trap.  In fact that’s what I usually call it, but it’s not really the same thing.

A sediment trap is just a T fitting in the gas pipe with a capped pipe nipple at the bottom of the T.  It’s required at a furnace, boiler, and water heater, but not at a clothes dryer, a kitchen range, or a fireplace.

The sediment trap needs to be installed downstream of the appliance’s shutoff valve and as close to the appliance as practical.

And it needs to be installed so that the gas flow changes direction, so that the debris will fall into the trap.  If you install it so that the gas flows horizontally (like in the picture below) then the debris might just jump over the trap and get into the gas valve.

This sediment trap is not installed correctly.

There’s no excuse for the lack of a sediment trap.  A competent plumber knows it’s required by all relevant codes and by the appliance manufacturer’s instructions.  And you don’t want an incompetent plumber installing your gas pipes.  So if it’s missing that’s one strike against the plumbing system as we work on telling the story of the house.

But how bad is this problem, really?  Well, I’ve heard that this might have been an issue many years ago, but today the natural gas delivered to your house generally is clean and dry.  And I’ve never personally heard of a problem that occurred because of a missing sediment trap, although I have heard stories of clogged gas valves.

So have a sediment trap installed the next time the appliance is replaced.  In the meantime it’ll just be one of the many things in your house that’s not perfect.

Inspection Overview
Why Get a Home Inspection?

Recent Posts

Chimney Crown

The chimney crown is the concrete (sometimes stone) layer that covers the top of a masonry chimney.  It’s one of those classic “out of sight, out of mind” components of your house, since it’s way

Failure Modes

Last spring I was doing some work to my gutters and downspouts.  I was running a new downspout extension out past the front of my porch to make it easier to maintain.  So I bought

Grease traps

Many of the older cities in the Chicagoland area have combined storm and sanitary sewers, meaning that the rain water drainage is collected through the same pipes as the sewage from houses.  This type of

Nonmetallic Sheathed Cable

Throughout the vast majority of the U.S.A., nonmetallic sheathed cable (NM cable) has been the most common type of residential wiring system since about the early 1950’s.  And it’s had a pretty good track record

Request Inspection

More Posts You May Find Interesting

Chimney Crown

August 30th, 2022|Comments Off on Chimney Crown

The chimney crown is the concrete (sometimes stone) layer that covers the top of a masonry chimney.  It’s one of those classic “out of sight, out of mind” components of your house, since it’s way

Failure Modes

August 30th, 2022|Comments Off on Failure Modes

Last spring I was doing some work to my gutters and downspouts.  I was running a new downspout extension out past the front of my porch to make it easier to maintain.  So I bought

Grease traps

August 30th, 2022|Comments Off on Grease traps

Many of the older cities in the Chicagoland area have combined storm and sanitary sewers, meaning that the rain water drainage is collected through the same pipes as the sewage from houses.  This type of

Nonmetallic Sheathed Cable

August 30th, 2022|Comments Off on Nonmetallic Sheathed Cable

Throughout the vast majority of the U.S.A., nonmetallic sheathed cable (NM cable) has been the most common type of residential wiring system since about the early 1950’s.  And it’s had a pretty good track record

Mold

August 30th, 2022|Comments Off on Mold

I frequently get asked if my inspections include mold testing.  With this blog post I’m going to answer questions about mold and mold testing.  Much of the information here is taken from this document from

Fire Sprinkler Systems

August 30th, 2022|Comments Off on Fire Sprinkler Systems

Fire sprinkler systems are becoming very common in new construction and major remodel projects, and so here’s a brief primer on residential fire sprinkler systems. When it comes to enforcing life safety codes in commercial