Two years ago I remodeled my two floor home. On the second floor, next to the main bath, I installed an over/under washer/dryer combination. I installed a pan under the unit in case of overflow which drains down a plastic hose to the basement. The main washer drain, along with the drains for the bath and shower and the supply water lines run down a wall (all within about 2 feet of each other) which on the first floor is behind the kitchen sink.
The problem is that when then upstairs washer is used for approx. 3 loads, I am getting condensation on the ceramic tile wall in the kitchen in the vincinity of the drains/supply lines.
Can anyone tell me why I am getting this condensation and what I should do about it? Is this indicative of a leak in the drain line, improper insulation or venting?