Why are all laundry standpipe receptors "open?"
Well, we have the wall exposed to the laundry area's "wet" side. Since the "drain-burp" sound is most annoying when using a condenser dryer, I thought a "closed" laundry drain system would help to dampen the noise. Why are all laundry standpipe receptors of an "open" design?" Here's one receptor which still provides an air-gap: