This house had a mystery steam leak that was causing the boiler to take on huge quantities of water. The interesting part though was that we could find no underground return pipes in the house and saw no water or leaks. When we flooded the boiler, it was also okay. Where was the water going? Finally the leak got bad enough where the homeowner called up and said she noticed condensation inside her stove. Thats when we found the pipes above the basement finished ceiling that didn't go up, but penetrated sideways through the garage. No one ever looked in the garage as there is no heat there. We chiseled holes into the slab and found these pipes and replaced them. Finding leaks can get very interesting!