The Advanced HVAC class drip leg question

I’m taking the class, and the instructor, Bill Mele, says that a drip leg is required on the gas inlet for “all” furnaces in “all” jurisdictions. I haven’t seen a drip leg yet in California. What’s the story?

Drip leg or sediment trap?

he said drip leg to capture moisture and dirt in the gas.

Sediment trap, dirt pocket or drip leg

Footing, footer :roll:

Nope. Different items used for different purposes.

So please explain.

Best explanation is by Jerry Peck.

A “drip leg” is located at the lowest point in the gas line system, and there may be more than one “lowest point” in that it is seldom that the gas piping is run horizontally or at a continuous slope, meaning the gas piping is usually run up and around things, then back down and around things, then back up, and each low point would require a drip leg IF the gas was considered to be wet gas.

A sediment trap, on the other hand, is located just before each appliance and each appliance requires a sediment trap* … with the * meaning there are always exceptions to the rule.

The easiest way to remember the exceptions to requiring sediment traps is this way: if the operator of the appliance (i.e., the appliance is not automatically started) can see the flame, or, more importantly, see the lack of a flame, the appliance is typically referred to as an illuminating appliance and does not require a sediment trap as the operator of the appliance would know, should know, to turn the appliance off when it does not light or the flame goes out. An exception to this ‘easy to remember’ method is clothes dryers - you cannot see the flame but for some reason they are lumped in with the other illuminating appliances and do not require a sediment trap.

Thanks Stephen I have never heard it explained that way.

This drip leg was correct because it was used on propane but if the gas was Natural gas it would be incorrect in Okla:shock:

Please reread the original question. Is the class disseminating misinformation?

Based on that statement aloneit would be a false statement Propane does not require a drip in Okla and any furnace on the exterior as in my pic of the Package unit does not require a drip with wet gas because the moisture will freeze in the drip leg. So one statement does not cover all situations

Yes, it is.

Many years ago a thread here on the Message Board caused me to seek advice from the people who I think would know best: San Diego Gas & Electric. So I did. They said that it is not required here in San Diego or in any of the SDG&E jurisdictions. They also explained to me that they are not required for most jurisdictions west of the Mississippi River. Had something to do with clean/dry gas and dirty/wet gas.

In my 14+ years as a home inspector (I retired 12/31/15) and 11,800+ inspections, I saw a grand total of 3 drip legs/sediment traps/call it what you will… I think that the plumbers who installed them probably came here from some place east of the Mississippi River…

The last time I looked I was west of the Mississippi none the less Okla has wet gas and drip legs are required indoors only . Not in attics and not on the exterior;-)

Thanks for the input. Enjoying your retirement?

I think SDG&E meant where you get your gas from, not where you live. Nonetheless, you stated that Oklahoma has wet gas. 'Nough said.

Yep. Got lots of other things going on so it’s no retirement per sé, just a retirement from home inspections.

I saw one!!!

I almost burst out laughing when I saw it, because, as you know, it’s a very rare thing out here.

IRC says basically “Drip Legs” go at low spots in gas piping if water vapor is in gas.

Let me think about this for a minute. As a home inspector HOW do I know if water vapor is in the gas?? I guess I don’t … SO if its NOT there we call it.

Other regions may vary BUT here I see them in almost every house.

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Manufactures as well.