Washing Machine Drain Question

Looking for some help here...

My washing machine has a standpipe that is about 33" and goes out of the house and into the ground into its own waste drain (underground). It does not drain into our main stack. We are getting a little smell from the top of the standpipe. The setup does not have a "p" trap. Here are my questions:

1) Should I install a "p" trap to eliminate the smell?

2) Do I need to install a vent on this? If so, how do I do that?

3) If I installed a Air Admittance Valve (AAV), would that replace the vent option?

Any help is GREATLY appreciated.
Thanks.

1. You should definitely have a p-trap.
2. You should definitely have a vent.
3. AAV's don't work well with washing machines, the sudden dump from the machine can/will cause positive pressure in the drain line keeping the drain from draining.

How do I install a vent?

Is a P trap required for a washing machine drain?

strobelw said:

Is a P trap required for a washing machine drain?

Click to expand...

Of course it is...

Why do you think you are getting an odor? One of the purposes of a vent is to seal gas and odor from getting into the house. The vent is installed after the p trap and must either join another vent to the outside or extend through and above the roof.