We have a 2011 FC 27 FB. It seems that whenever we open the kitchen sink drain to empty a fairly full load of water, we notice that the shower drain gurgles and gray water backs up into the shower pan. We've found we can avoid this backup two ways, insert a plug in the shower drain or interrupt the sink draining a couple times to slow down the flow. This is more of an irritant than anything else, but I'm wondering if it indicates the vent is plugged or something else that is serious.
So my question: is this normal, and/or has anyone else had this problem and fixed it?
Thanks for the help,
As far as I know, this is the oldest I've ever been.