There are many reasons why you should know what kind of gas your dryer uses. One reason is so that you can know if the dryer requires a drip leg.
So, drip legs are not required for all gas dryers. Where they are required, drip legs are crucial to extending or maintaining the lifespan of the unit and also the gas supply system. It also impacts the effectiveness of the dryer.
Gas dryers only need drip legs if they are fuelled by wet gases because these produce condensate that needs to be collected by the drip legs. Natural gas, supplied by the municipal lines, is a dry gas, so these dryers don’t need drip legs.
What Is a Drip Leg and What Is Its Purpose?
When supplying your appliance with gas, sometimes sediment and condensate can get caught in the gas line.
The sediment is dealt with by sediment traps, which people often think are the same as drip legs. This is incorrect, however, as you can see in my comparison article: Drip Leg Vs Sediment Trap (They Are Not the Same).
A drip leg is a simple T-shaped addition to the pipeline that removes condensate from your gas supply before the gas reaches the gas chamber of your appliance.
It is vertically positioned at a low point in the pipeline so that the top of the T is in line with the gas line and the leg of the T falls below it.
As the gas passes through the top of the T, all the condensate, which is typically heavier than the gas, will fall into the drip leg (the leg of the T), without altering the flow of the gas.
Drip Leg Required With Wet Gas According to IRC
Something you may not know is that fuel gas can be categorized as either dry or wet, depending on the amount of moisture (liquid gas) that is present in the supply.
According to Section G2419.2 of the International Residential Code (IRC), at any point where wet gas exists it is required to have a drip leg that can remove the condensate from the supply before it reaches the appliance that it is fuelling.
Is Gas Dryer Gas Wet or Dry?
Gas dryers can use either natural gas that is supplied by pipes or it can be powered by liquid propane (if converted).
Natural gas from the municipal supply is mostly methane (as opposed to liquified gases) and is considered to be a dry gas that does not produce condensate.
Liquid propane, as the name may suggest, is a wet gas because it is composed of liquified propane gas. Because of the moisture content, condensate can be an issue with liquid propane gas, so a drip leg is required.
Most dryers are designed for use with the natural gas supply from the municipal lines. However, if you do not have access to these supplies or if you prefer not to rely on them, then you can install a liquid propane tank and convert your dryer using a liquid propane conversion kit (amazon link).
Where to Place the Drip Legs
According to Section G2419.2 of the IRC:
- A drip leg is required at any point at which condensate can collect. This is likely to be the lower points in the piping system.
- A drip leg is required at the meter outlet (the gas regulator that is situated outside of the tank) and must be installed in such a way that if there is too much condensate, the meter will shut off before the condensate can flow back into the tank.
Then in Section G2419.3, it says that:
- The drip leg must be located somewhere that is easy to access. The purpose of the drip is to collect condensate but you have to be able to empty it for it to continue functioning properly.
- The drip leg mustn’t be placed anywhere subject to freezing temperatures. If it were in such environments, then the condensate could freeze and cause damage to the gas pipes.
What Would Happen if There Was No Drip Leg?
If the gas regulator is constantly exposed to the condensate it could cause the springs of the regulator to rust, thus hindering its ability to regulate and provide an adequate flow of gas to the appliance.
Another issue with the lack of the drip leg is too much liquid in the gas supply, which can disrupt the gas flow.
Since gas dryers are powered by a gas supply, this low supply or blockage may hinder the drying ability of the dryer by not generating enough heat to dry your clothing. Giving you half-damp clothing at the end of a full cycle.
Apart from the heating, your gas dryer should run smoothly as the rest of your dryer is powered by electricity. You can use this as a diagnostic principle to focus your attention on the gas burner assembly and supply.