Direct answer: Most HRV water leaks come from a blocked or disconnected condensate drain, a dry or missing trap, or water forming where it should not because airflow or frost control is off. Start by figuring out whether the water is coming from the unit cabinet, the drain connection, or sweating ductwork nearby.
Most likely: The most likely cause is a condensate drain problem at the HRV itself: slime, debris, a sagged hose, a loose drain fitting, or a trap that is missing water seal or installed wrong.
An HRV can make some condensate in cold weather, but it should leave through the drain, not onto the floor or ceiling below. Reality check: a small puddle under the cabinet usually points to drainage first, not a failed unit. Common wrong move: clearing only the visible end of the drain tube and missing the clog or bad slope right at the HRV pan outlet.
Don’t start with: Do not start by replacing the HRV core, fan motor, or controls. Those are not the usual reason a homeowner finds water on the floor.
Water is on the floor below the unit, often near one corner or under the drain side.
Start here: Start with the condensate drain outlet, hose, trap, and whether the unit is sitting level enough to drain toward the pan outlet.
You can see water at the fitting, trap, or hose, or the tube drips only while the unit runs.
Start here: Look for a loose fitting, cracked tubing, a sag that holds water, or a clog backing water up to the connection.
The cabinet may be dry, but metal duct or insulated flex near the unit is wet or sweating.
Start here: Treat this as a condensation issue first. Check for cold surfaces, missing insulation, air leaks, and whether the nearby branch matches /hrv-condensation-drips.html or /erv-duct-condensation.html.
The leak is worse on very cold days, after frost buildup, or when the unit cycles through defrost.
Start here: Check for ice inside the cabinet, blocked drain passages, restricted filters, or a frost-control problem that lets meltwater overwhelm the drain path.
This is the most common floor-leak cause. Water collects in the pan, then spills from the cabinet or backs up at the drain fitting.
Quick check: With power off, inspect the drain outlet and tubing for slime, debris, kinks, or standing water that should not be there.
A bad trap setup can slow drainage, let air interfere with flow, or leave water sitting until it spills out elsewhere.
Quick check: Follow the drain tube from the unit to the drain point and look for a proper trap shape, steady downward slope after the trap, and no low spots full of water.
If the cabinet is mostly dry but nearby metal or insulation is wet, the water is usually forming on the outside of cold duct surfaces.
Quick check: Wipe the cabinet and ducts dry, run the unit, and watch where fresh moisture first appears.
Dirty filters, blocked exterior hoods, or defrost trouble can let frost build up on the core area. When it melts, the drain may not keep up.
Quick check: Check filters, outdoor intake and exhaust hoods, and look for ice or heavy frost inside the accessible service area.
Water often shows up below the real source. You want to separate a true cabinet leak from a sweating duct or a plumbing-style drip at the drain tube.
Next move: Once you know the first wet point, the rest of the checks get much faster and you avoid chasing the wrong problem. If everything is wet and you cannot tell where it starts, move to the drain checks next because that is still the highest-probability cause.
What to conclude: A leak at the cabinet bottom usually points to drainage or frost melt inside the unit. Wet duct surfaces point to condensation outside the unit.
Most homeowner leaks are right here. A small clog, loose connection, or bad slope can put water on the floor fast.
Next move: If water now drains cleanly and the leak stops on the next run cycle, the problem was the drain path, not a major component failure. If the drain path looks good but water still appears from the cabinet, check for internal ice, debris in the pan area, or poor unit pitch next.
What to conclude: A backed-up or badly routed drain lets normal condensate spill out of the unit. A dry or wrong trap can also upset normal drainage.
Restricted airflow and frost buildup can create more meltwater than the drain can handle, especially in cold weather.
Next move: If airflow improves and the leak fades after frost clears and the drain stays open, the unit was likely making too much meltwater because of restriction or icing. If there is repeated frost, recurring ice, or water still bypasses the drain after cleaning, the unit may need service for defrost control, setup, or airflow balancing.
Even with a clear drain, water can miss the outlet if the unit is tilted wrong, and sweating duct can fool you into thinking the HRV itself is leaking.
Next move: If correcting support, insulation, or air leaks stops the moisture, you were dealing with drainage geometry or duct sweating rather than a failed HRV part. If the cabinet still leaks with a clear drain and no duct sweating, the internal pan, drain connection, or frost-control operation needs closer service inspection.
A short test after cleanup tells you whether you fixed a simple drain issue or whether the unit needs service for an internal or control-related problem.
A good result: You likely solved a drain or maintenance problem. Keep the area dry and recheck after the next heavy-use or cold-weather cycle.
If not: At that point, stop guessing on expensive parts. The remaining causes are usually internal drainage geometry, recurring icing, or control-related operation that needs hands-on service.
What to conclude: A leak that survives a clear drain and basic maintenance is no longer a simple homeowner cleanup issue.
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Winter leaks usually come from normal condensate not draining correctly, or from frost buildup that later melts faster than the drain can handle. Start with the drain line, trap, filters, and outdoor hood restrictions before assuming a major failure.
Yes. In cold weather, an HRV can produce condensate. What is not normal is water escaping the cabinet, dripping from the wrong place, or soaking nearby ductwork or building materials.
Yes. A dirty HRV filter can reduce airflow enough to encourage frost buildup inside the unit. When that frost melts, you can end up with extra water and an overflow if the drain path is marginal or partly blocked.
That usually means the connection is loose, the tubing is cracked or kinked, or the line is backing up from a clog or bad slope. Check the fitting at the cabinet first, then follow the tube and trap all the way to its drain point.
Call for service if the drain is clear and routed correctly but the cabinet still leaks, if the unit keeps icing up, if water is reaching electrical parts, or if the leak has already damaged ceilings, insulation, or walls. At that point the problem is often internal drainage geometry, defrost operation, or setup that needs hands-on diagnosis.