View Full Version : OT. Air Compressor tank drain question

Mr Fixit
12-23-2017, 03:20 PM
Hi Group,

I have a remote air tank only and now a new (used) refrigerated air dryer in the upstairs of my shop. I have a 1/2" copper drain line off of the tank to the outside with the valve down stairs that I manually drain once a week or more as I remember.

I for the life of me can not figure out how to tie the drain of the air dryer into this drain and keep the air tank from draining. I thought about a check valve but wrong application. I would like to keep it in the same line since it is plumbed inside the wall down stairs.

I know I'm trying to mix water and air, pressure vs gravity flow, but I sure would like to use the same line if at all possible. Definitely no pipe on the outside of the building will be considered as exterior looks are important for the shop per the wife, the inside is all mine just don't let it come outside she says..

So what I'm looking for is all the collective minds here to toss out a possible solution to my dilemma.

Mr fixit for the family
Chris :)

The Artful Bodger
12-23-2017, 03:24 PM
Obviously I do not know the layout of your home and shop but if the question is where to drain water indoors I suggest breaking into a sink wast pipe above the water trap or some such. I would not drain into the toilet flush pipe as any discoloration of the toilet water or bowl would become your problem!

12-23-2017, 03:30 PM
Or simple tap the dryer drain into the tank drain link after the tank drain valve.

12-23-2017, 04:50 PM
Or simple tap the dryer drain into the tank drain link after the tank drain valve.

With a valve in each line so you don't back feed the dryer when you open the compressor valve.

12-23-2017, 05:09 PM
Get one of the water traps that blows off when it gets a bit of water into it.. Put it upstairs above your existing drain line.. Maybe
some type of a collector like an upside down soda bottle on top of the existing drain line and then just run your dryer drainer line to the same
spot.. Then you don't even need to remember to open the valve, just leave it open.

OR... Just let the dryer drain dump on the floor, or a cookie sheet, or into a bucket or something.

Mr Fixit
12-23-2017, 05:20 PM

I don't have the best ability to explain things sometimes and I get a bit wordy. What I want to do is tee the drain of the air dryer into the tank drain upstairs so I can use the one valve down stairs to drain it without going up and down the pull down stairs. what I'm looking for is if there is a one way device to keep the air from leaving the tank via the air dryer drain line but still let the water make it's way down stairs to the valve.

In typing this second description to the question I see this really won't be possible because of the air pressure in the line it's self. So thanks for the help, I will just have to run a separate drain line for the dryer down stairs so I can let it exit outside on it's own.
Sometimes just dialog with others helps.


Mr fixit for the family
Chris :)

Mr Fixit
12-23-2017, 05:33 PM
Hi bobw53,

That may be the fix. stop trying to use the drain line under pressure from the tank to the outside. Terrific, then I wouldn't need to run a second line, just use the one as a gravity feed vs a pressure drain line.

Mr fixit for the family
Chris :)

12-23-2017, 06:24 PM
If you can get away with a small orifice in the air tank drain close to it but before the dryer T (which will also need a check valve on the line to the dryer) when the end tap is opened the water will drain out but the small orifice will not feed enough air into the line to raise its pressure once the tap is open. The dryer may need a little help with a few psi to overcome the check valve spring. If the dryer is an open tank that cannot be pressurised then a small pump may be needed.