AskCodeMan

Dear Codeman,

I've seen some comments that indicate that drip legs ARE NOT required when wet gas is not delivered. In my area (Virginia), Washington Gas hasn't delivered wet gas for a long time; yet a home inspector is telling me that a drip leg needs to be installed on the gas line.

If he's confusing with a sediment trap (he doesn't realize it's two different things?) - how can I tell if I have an internal sediment trap? Or if an external one needs to be installed?

Many thanks in advance for your assistance.

Jerry Peck - Codeman wrote:If he's confusing with a sediment trap (he doesn't realize it's two different things?)

Ruth,

That is what it sounds like to me - that the home inspector is making an all-too-common mistake of generalizing "drip legs" and "sediment traps" as one and the same.

Even though drip legs and sediment traps are constructed the same way, they serve two entirely different purposes and are located at two entirely different locations in the gas line system.

how can I tell if I have an internal sediment trap? Or if an external one needs to be installed?

The manufacturer's installation instruction would state if there was a sediment trap installed, which would be rare.

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.