Sediment traps have been required on gas piping systems for many years, but there is a lot of confusion about them. Read on to learn what they really are, where to install them, and how to configure them properly.
Sediment Trap vs. Drip Leg
“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. Wondering why you have never seen one of these? They are not required where the local gas utility provides “dry gas” – which is defined as “a gas having a moisture and hydrocarbon dew point below any normal temperature to which the gas piping is exposed.”
On the other hand, sediments traps are installed to collect sediment, rust, or debris in a gas piping system that can clog a gas appliance burner and cause a malfunction.
Which Appliances
According to section 1212.9 in the 2022 California Plumbing Code (CPC), sediment traps are required for all gas appliances except: illuminating appliances, gas ranges, clothes dryers, decorative appliances for installation in vented fireplaces, gas fireplaces, and outdoor cooking appliances. Those are quite a few exceptions. Most homes need to have sediment traps installed on the gas piping supplying water heaters and furnaces.
Where to Install
This section of the plumbing code has been changing in the last few code cycles, creating some confusion. For a while, sediment traps were required “as close as practical” to the appliance, which led many installers to put the sediment trap after the flexible gas connector. The 2016 CPC clarified that the trap should be installed after the appliance shutoff valve, but before the flex connector. Presumably, this is to facilitate cleaning the trap.
How to Configure
According to the CPC, a sediment trap “shall be either a tee fitting with a capped nipple in the bottom outlet, as illustrated in Figure 1212.8, or other device recognized as an effective sediment trap.” It’s important to note that Figure 1212.8 shows the gas coming in the top inlet, not a side inlet of the tee fitting. When running gas piping for a new appliance, installers should run the piping high enough that it can run down to the sediment trap – to avoid potential complications. An internet search did not reveal any proprietary devices, so it looks like installers will be making their own for the time being.
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After a friend generously installed a sediment trap on our 50 gallon water heater, there was just BARELY enough hot water for one adult to take one shower. The bottom of the trap was below the gas supply line as well as I could see.
Help!
James-
There are simply too many factors to account for to make a semi-educated guess over the internet. You’d better call a plumbing contractor.
A sediment trap would have nothing to do with that. Now, when the gas was turned of and back on maybe some sediment made it into the control or maybe he did not turn the temp up as high as you had it.
Did he relight the pilot light on the water heater or turn the gas valve back on? I’ve seen that happen many times even with Pros
What causes a tartar like substance on a gas line under a mobile home?
I don’t know, do you have a photo? Presuming that a “tartar like substance” is white in color, I would think that it was mineral build-up … but I have no idea why mineral build-up would happen on a gas line, unless you have a leak or water is dripping onto the gas line.
Bottom line: don’t mess around with gas piping, have a plumber come check it out to make sure everything is safe.
Thread sealant should be wiped clean after install,but lots of young plumbers skip this step.
Many gas appliances like furnances, tankless water heaters and many others have a sediment trap built in that you can’t see unless you disassemble the unit. If a home inspector wants to install one on a 20 or 30 year old home, tell him to pound sand, breaking into old lines is asking for trouble. If you really want one or two, wait until you replace the old appliance.
If you can send me an appliance diagram that shows an appliance with a built-in sediment trap, I’d love to see it. I’ve never heard of such a thing.
Regardless, the California Plumbing Code requires sediment traps on the gas appliances listed in this post. Feel free to argue with the wisdom of this code provision, but you can’t argue with the code.
I am surprised that an inspector of your tenure has never heard of appliances with built in sediment traps. Maybe, like a lot of other things the rest of us enjoy, they are not ‘approved’ in California. :-p
Regardless, the code requires a sediment trap, but it does not specify it must be the typical tee trap. An appliances built in trap is an “other device recognized as an effective sediment trap.” This thereby removes the need for the rigid pipe trap and csst can be connected directly to the appliance.
Some gas control valves have a fine screen on the inlet, but such a screen is not a “sediment trap”…
When did sediment traps become a requirement. I had my water heater replaced in 2018. I just had a home inspection and they’re saying one needs to be installed. Should this have been done during the initial install?
Thank you
Rich-
The California Plumbing Code has required sediment traps for many years, well before 2018. A quick search revealed that the plumbing code required sediment traps in the 2007 CPC.
In my 70 years of being around/using gas appliances in California, i have never once had the appliance fouled by sediment. I think this requirement in California only exists because of code writers with too much time on their hands.
I have never seen one in any home in California that I’ve lived in or worked on. I also maintained apartments for 12 years, on multiple different properties, in different cities I have seen zero of these ridiculous things anywhere. Why are they even needed? If any appliance should ever stop working because of a clog, then that’s just more money for the manufacturers.
Please provide your advice and insight into this problem. My home recently stopped heating. I called a Heating and Cooling professional. He provided the following information:
Replace
Replace Forced Air Furnace
Failure Reason
Missing Components/Parts
Contractor Note
The gas valve is clogged due to missing gas sediment trap not filtering causing gas valve to fail. The failure is due to misaing part. Need to replace the valve but the part is no longer available.
Because this part is no longer available . The ffg-cod will need to be replaced at an estimated cost of $3300.00.
Does this explanation sound reasonable?
The explanation sounds completely reasonable, especially if you have an older furnace (you never mentioned the age).
It’s always a good idea to get multiple bids to make sure you are getting a reasonable price. In addition, there may be other HVAC types (such as a heat pump) that will cost you more money upfront, but will save you money long term since they are 3-4x more efficient than the most efficient gas furnace.
Being fully aware that many codes require the installation of a drip leg in the gas line to a water heater or furnace. What do you tell the owner if he asks you how often the drip leg has to be emptied out, every year, 5 years, 10 years? Is the home owner allowed to do this himself, or does he need a plumber to come and do it?
I have never heard of anybody ever emptying a drip leg; so, if that is the case, why do we still require drip legs?
Is it because of the famous “we always did that” or because it has been in a code first issued before the second World War when gas wasn’t as clean and as dry as it is today?
As mentioned in this post, drip legs and sediment traps are two different things, and should not be confused. I’ve never heard any advice on how frequently a sediment trap should be cleaned, as the frequency will depend on the quality of gas being delivered and condition of the gas distribution system. To start, it would be a good idea to have the sediment traps checked every time the gas is disconnected for service or replacement.