[glen]

Back in ancient times it was common practice for vehicles with air brake systems to have them drained daily. Today with very effective air dryers it is no longer necessary as long as the air dryer is serviced properly.

Having said that it does no harm to install them and to get a feeling like an old trucker pull the cable and listen to air escaping every day. But there is a down side. The first problem is you lose the opportunity to see what comes out when you open the drain. Ideally you want to watch the drain until all pressure in the tank has been depleted because if there is water in the tank the high pressure air in it blows a hole through the water and until the pressure is almost totally gone you won’t see water draining. You do want to see moisture if it is present because it is a clue the dryer needs to be serviced.

The second benefit that does remain is that any time you drain the tanks, at least drain them in sequence starting with the wet tank, primary, secondary, and accessory. As long as each tank in sequence retains pressure you are verifying the integrity of the system check and protection valves.

I change my dryer cartridge every two years and every 5000 miles I am under the coach draining my tanks looking for moisture. I get none. Nada. Zero moisture. Our dryers work very well.

If you are looking to protect the air system make certain your aux compressor is not putting moisture in the accessory tank. Very few conversions have adequate protection against that problem and as an owner you have the opportunity to consider the addition of a dryer or moisture trap to protect the system from your aux compressor moisture.