Gas Line Sediment Trap Or Escape Hatch?

Home Inspector with Greens Home Design L.L.C. AZBTR #49380

Here is a great post by Jay Markanich on proper placement of shut off valves.  This is an important thing to look for when purchasing a Phoenix home.

Original content by Jay Markanich 3380-000723

So, is this a gas line sediment trap or escape hatch?  You decide.

The features list in the house said, "Newly installed HVAC system 2011!"  All true.  And done professionally!

Judging from the duct work the previous system was quite old.  Replacing it was only smart.  And good for my clients!

The sediment trap is the longer section of black iron gas tubing that is sticking straight down.

It has been called by various names, and there are those who split hairs and say that only the term "sediment trap" is correct.  But still, it is what it is.

The purpose is just as its name says.  Historically, when natural gas was first pumped into houses it came with sediment and moisture.  That could all get into and damage the appliance using the gas.

So they devised a trap, which you see to the left, to capture that as it would fall harmlessly into the bottom of the lowest section.  In the "olden days" they used to remove that section of pipe periodically to dump out the trapped sediment.  The extended pipe should be 3" minimum.

Fine.  Today our gas is cleaner and drier and there are those who say that the traps may not be necessary.  But still, most installation practices require them. 

I have spoken with plumbers who say they should not be used outdoors or in attics as the moisture trapped inside could freeze and cause the pipe to burst or move the nipple at the bottom causing a leak.  But still, most codes require them.  When I don't see a sediment trap present I note it for my client.

You can see the new piping here, new condensate line, new cables, new switch servicing the new humidifier and new condensate pump - new, new, new!  They did it right.

But wait!  What's wrong here?  This is a new system, installed by a professional because they proudly placed their company sticker, with installation date, onto the unit.  It also says, "Please call US to answer any future questions or to satisfy any future needs!"

So, again, what's wrong here?

Looking closely, as a home inspector is supposed to do, you might notice that the gas shut-off valve is between the sediment trap and the furnace!

If someone wanted to remove any debris from the sediment trap (and I have spoken with many, many plumbers who say there is no debris in modern times, but I digress) and dutifully shut off the gas valve before beginning, gas would still escape from the sediment trap tubing!

Obviously there is a way around this still.  The main gas line valve on the indoor manifold, or the gas meter itself, could be turned off to safely remove the sediment trap.  But that would turn off the gas to other appliances, and any pilot lights in the house, such as the water heater, and cause unnecessary work as they would all have to be relit.

The shut-off valve really should have been placed BEFORE the sediment trap.  This current installation might even indicate the valve was not correct from the start as this company mimicked what the previous installation looked like!  But I really don't know.

My recommendation:  when a home inspection is done, it is important to see the whole picture.  A little thing like this might go unnoticed forever, and maybe not even by the professional HVAC company, but it was not unnoticed on this inspection!  And at least it's a simple fix.  I guess that company is going to get called after all!



Jay Markanich Real Estate Inspections, LLC

Based in Bristow, serving all of Northern Virginia

Comments (0)