A standard efficiency furnace extracts some heat from the combustion gases and quickly vents them out the exhaust or flue pipe.
Gas furnace flue pipe leaking water from storm.
If your flue pipe is improperly sized or was installed incorrectly the gases move too slowly allowing them to cool down condense inside the flue and drip back toward the furnace.
This includes the drain pan and the drain piping.
If you have a condensation leak with a standard efficiency then its exhaust or flue pipe may be incorrectly sized.
If this is the case it could be an incorrectly sized flue pipe which is making water to drain back into the furnace.
Improper flue exhaust can result in your furnace leaking water.
It sounds like the flue gas is condensing before it has left the flue.
Exhaust pipe restrictions will cause the pressure in the flue to rise creating positive pressure and inhibiting proper exhaust.
If you have a standard efficiency furnace usually 15 plus years old it should not be leaking water.
This can cause premature flue failure.
Like all installations that poke through the roof sometimes a flue pipe develops leaks that result in water leakage into the attic or roof space when it rains.
B vent leaking from seam in pipe.
Your humidifier should be getting annual maintenance from a professional to prevent this.
This will cause your gas furnace to leak water.
Much of the drain system and some of the parts are made of plastic.
If the pan is cracked it needs to be repaired.
While this may look like water leaking from your furnace it s actually furnace gases that have turned into their liquid form.
There should be no water involved with a standard efficiency furnace.
Other causes of leaking water around a furnace if you have a conventional standard efficiency furnace then its flue pipe may be incorrectly sized.
The water drips on a piece of wood in the attic which apparently has always dried before causing an issue.
A number of points may fail in the flue but they are mostly easy to detect and fix.
You ll need a furnace technician to diagnose which of these is the issue and then fix it.
In a gas heated home a flue pipe vents the gases out through the roof.
There are other reasons why your condensing gas furnace can leak water.
If this is the case it s best to call your local furnace repair team.
There s a chance this has.
In some circumstances the plastic can be cracked.
Broken condensation line condensate pump.
If you have a whole house humidifier connected to the furnace there may be an issue which is causing the humidifier to leak into your furnace.
Improperly installed vent connector that reduces exhaust velocity.
