Ceiling stains can also be the result of urine from pests in your attic or even in a floor system. If you have eliminated the potential for plumbing or roof leaks, try looking for evidence of a pest infestation. Some other signs that you have unwanted guests in your house are droppings and tracks or tunnels through insulation. If you discover that you have a pest infestation, there are many companies that can remove the pests and seal any openings in your house.
Water on the floor around a furnace: Water appearing on the floor around a furnace will typically only occur in the summer. However, if you happen to have a high efficiency, condensing furnace it can also occur in the winter. During the summer your air conditioner is not only cooling the air in your house but it is also drying the air out.
The moisture that your air conditioner draws out of the air is normally piped to the exterior of the house. Sometimes, the pipe becomes clogged. When it does, the water will leak onto the floor around your furnace.
Since an air conditioner will typically draw gallons of water from the air daily, you will end up with a fairly large amount of water around the furnace. To solve this problem, I recommend calling a licensed heating and cooling contractor. Although clearing the drain pipe is usually easy, a licensed professional will make sure nothing else is wrong with your heating and cooling systems.