A puddle on the basement floor under the furnace in the middle of winter confuses people, because a furnace burns gas and should have nothing to do with water. High-efficiency furnaces make water every hour they run. Older furnaces leak water for reasons that have nothing to do with the furnace. Every HVAC Brooklyn technician checks the same four things, and the first question is whether the furnace is a 90-percent-plus condensing model or an 80 percent standard one. The answer tells you which list applies.
High-Efficiency Furnace Condensate Leaks
A condensing furnace pulls so much heat out of the exhaust that the water vapor in it condenses, about a gallon per hour at full fire. That condensate drains through a trap, a drain line, and usually a condensate pump in a Brooklyn basement, and then to a floor drain or a sink. A clog anywhere in that path backs water up and out the first opening it finds, which is the bottom of the furnace cabinet. The trap clogs with sludge. The drain line sags and holds water that freezes near an exterior wall. The condensate pump float sticks or the pump motor dies, and the pump reservoir overflows onto the floor. Pumps run on a float switch and a safety switch, and the safety switch wired to the furnace shuts the furnace down when the reservoir fills, which is why some condensate leaks show up as a no-heat call instead of a puddle. A cracked trap or a loose hose clamp drips steadily. Clearing the trap and the line with a wet vac and flushing with warm water fixes most of it. A dead pump costs $150 to $300 replaced. Condensate is mildly acidic, and a pump installed without a neutralizer cartridge where the code requires one eats the floor drain over time.
Standard-Efficiency Furnace Flue Problems
An 80 percent furnace vents through a metal flue into a chimney or a sidewall vent. If the flue pipe is undersized, too long, or runs through a cold space, exhaust cools before it exits, condenses inside the pipe, and runs back down to the furnace. Rust streaks on the flue pipe and water dripping from a joint near the furnace point at this. A masonry chimney without a liner collects the moisture and sends it back down too. The fix is a properly sized and insulated flue, often a chimney liner, and a furnace that shares a chimney with a water heater after a furnace upgrade is where this shows up in Borough Park and Midwood houses.
The Air Conditioner Coil Sharing the Cabinet
Most Brooklyn furnaces have a central air evaporator coil sitting on top in the same cabinet. In summer that coil produces condensate that drains through its own line. A clogged coil drain line, a cracked drain pan, or a frozen coil that thaws after shutdown puts water at the base of the furnace, and the homeowner blames the furnace. In winter a leak from the coil area usually means the drain pan trapped water last summer and a rusted pan is now letting it through, or the humidifier is the problem. Clearing the coil drain with a vacuum at the outside end and a cup of vinegar at the top clears algae, and a replacement pan is a coil-pull job.
Whole-House Humidifier Leaks
Bypass and fan-powered humidifiers mount on the supply or return plenum and feed water through a quarter-inch line to a solenoid valve and a water panel. A stuck solenoid runs water continuously. A scaled water panel overflows the distribution tray. A clogged humidifier drain line sends the overflow down the duct and out the bottom of the furnace. Humidifiers leak more than anything else attached to a furnace, and a unit that has not had a new water panel in three winters is a leak waiting to happen. Shutting the saddle valve on the water line stops the leak immediately while the humidifier gets serviced.
Plumbing Leaks Above the Furnace
A puddle under the furnace is sometimes a plumbing problem that landed there. A sweating cold water line in a humid basement, a weeping shutoff valve on a pipe overhead, a water heater drain valve dripping, or a sewer house trap cleanout plug seeping a few feet away all run to the lowest point, and the furnace sits in a slight depression on a lot of Brooklyn basement floors. Dry the area, run the furnace, and watch where the first drops appear before calling anyone.
What a Water Leak Does to a Furnace
Water at the base of a furnace rusts the burner assembly, the heat exchanger, and the control board if it wicks high enough. Standing water around a furnace cabinet corrodes it from the outside in. A furnace that has sat in water, even an inch from a basement flood after a storm in Canarsie or Red Hook, has its gas valve and board inspected before it runs again, and gas valves that have been submerged get replaced regardless of how they look. A small condensate leak left for a winter takes years off the equipment.
Picture a Bensonhurst homeowner with a 2016 condensing furnace and a puddle every morning. The condensate pump hums but does not pump. The float is stuck in sludge from eight winters without a flush. A new pump and a flushed trap, $280. The old pump had been overflowing onto the furnace base long enough to rust through the bottom panel, which is now the next conversation.
Brooklyn HVAC Company | AC & Furnace Repair
5305 13th Ave, Brooklyn, NY 11219
(929) 833-7835
NY
11219