Water near a furnace is usually condensate, not plumbing. High-efficiency condensing furnaces produce several gallons a day during the heating season, and that water has to drain. A blocked trap, cracked or disconnected tubing, a failed condensate pump, a clogged inducer drain or a damaged collector box will all put it on the floor instead. On standard-efficiency furnaces, water more often comes from the air conditioning coil above, from a humidifier feed, or from flue condensation.
Repeated shutdowns during cold weather often trace to the same cause, since a float switch cutting the system off is doing its job. In an unheated Ohio basement or crawl space, an external condensate line can freeze solid and back the water up. Pro HVAC connects homeowners in Shaker Heights, OH with HVAC professionals. Call (321) 463-9811.