So I had a plumber out to make my water heater drain pan:
drain to somewhere else other than the garage as I am building out the garage to use as a room. He ended up connecting the drain pan to the sewer in the wall next to the hot water heater as it has sinks on the other sides. He used a swing check valve:
to stop the sewer gas from going back into the water heater closet. My question ... is this sufficient to keep the sewer gas out? I have a feeling that its not and there should be some sort of P-Trap or something else to keep the gas out. I haven't been able to smell any sewer smell in the hot water heater closet yet but I am very concerned that it might be letting small amounts of gas through. Any help here would be much appreciated.