Walk-In Cooler Leaking Water: Where It Comes From

Water on a walk-in floor is almost always coming from one of a handful of places, and the location of the puddle narrows it down quickly. Most of the time it's the evaporator's drain system, which carries away the water melted off the coil in every defrost. When that path is blocked, tilted or frozen, the water finds another way out.

Safety: A wet walk-in floor is a slip hazard, and in a freezer it turns to ice. OSHA requires floors to be kept clean and, as far as feasible, dry, and warns that condensation in coolers and freezers makes floors slippery. Mop it, mark it, and keep people away from the wet area until the leak is fixed.

Where is the water?

The drain system, and how it fails

Every defrost melts the frost off the evaporator coil. The water drops into a drain pan under the coil, runs out a fitting, and flows through a drain line to an open drain outside the box. Heatcraft's installation manual sets out how that line should be installed:

• Pitch of at least ¼ inch per foot, so water runs downhill all the way.
• A trap in every drain line, located in a warm space.
• The line ends at an open drain, never piped directly into the sewer.
• On freezers, a continuously powered heater on the line and the drain-pan fitting, and traps outside the refrigerated space.

Each of those points is also a failure point.

Clogs. The drain pan collects dust, product debris and biofilm that grows in the cool, wet pan. Slime and debris wash into the fitting and trap and eventually plug them. The pan fills, overflows at its lowest edge, and drips onto the floor. A sour smell near the unit often goes with it; see smells and mold.

Poor pitch or sags. A line that sags or runs uphill holds water. In a cooler it grows slime faster; in a freezer, or anywhere it passes through the cold box, the standing water freezes.

Frozen drain. In a freezer, a failed drain-line heater or pan heater lets water freeze in the line during defrost. The next defrost's water backs up behind the ice, overflows the pan, and either drips on the floor or freezes onto the coil and product. Heatcraft lists ice in the drain pan as a sign of a defective heater, bad pitch, a plugged drain or a failed drain-line heater. See drain line heater.

Joints and traps. A drain line that has been bumped, a cracked fitting, or a trap that has frozen and split will drip along its route, often outside the box where no one looks.

Floor sink. Sometimes the walk-in drain is fine and the floor sink or drain it empties into is backed up.

A unit that isn't level

The drain pan is designed to slope toward the outlet. If the evaporator was hung out of level, or the ceiling has sagged or the hangers loosened, water pools at the low end of the pan and spills over the edge instead of reaching the drain. The giveaway is a steady drip from one end of the unit, away from the drain fitting, even though the drain line itself is clear.

Melting ice and frost

Not every leak is a plumbing fault. Ice that built up around the door frame, on the floor at the threshold, or on the ceiling will melt as soon as a door heater comes on, the box warms during a defrost, or the unit is shut down for service. That water runs to the lowest point and can look like a leak. If you've been seeing ice, the water is the symptom of that ice; see ice buildup in a walk-in freezer and frost around the door.

An evaporator that iced up and is now melting all at once will also overwhelm the pan. See evaporator coil frozen.

Panels, seams and roofs

Water seeping from panel joints or the base of a wall, with no drain nearby, suggests moisture in the seams or inside the panels. Warm, humid air leaking into a seam condenses on the cold surface inside. Over time the insulation can take on water, lose insulating value, and start to sweat on the outside too. See panels and insulation.

Outdoor walk-ins add weather. A roof cap with failed flashing or open seams lets rain into the ceiling, and it often shows up inside after storms. The site's guide on indoor vs. outdoor walk-in coolers covers why outdoor boxes need a weatherproof roof.

Checks staff can do safely

1. Mop up and mark the area so the next puddle shows you where it starts.
2. Watch where the water appears: under the pan, along the drain route, at the door, or from a seam. Note the time relative to defrost.
3. Follow the drain line from the evaporator to its outlet and look for drips, cracks, sags and ice.
4. Check the outlet end: is the floor sink or drain it empties into clear and flowing?
5. Look at the evaporator from below with a flashlight for an overflowing pan, ice or dripping from one end.
6. Keep product out of the drip path and off the floor near the leak.
7. Check for recent events: a new evaporator, work on the ceiling, a hard knock, or a storm.

Food safety: Don't store food under a dripping evaporator or where water can splash onto it. If product was dripped on, follow your food safety plan and your local health authority's guidance.

What a technician will check

• Drain pan condition, cleanliness and slope, and whether the unit hangs level.
• Drain line pitch, trap location and joints along the full route.
• Drain pan and drain-line heaters on freezers, including amperage.
• Defrost settings and termination, since overly long or ineffective defrosts send extra water to the pan.
• The fan delay after defrost, if water is also being thrown into the box.
• Panel seams and penetrations if water appears away from the drain.

Cleaning the drain pan and flushing the line are part of routine service. Heatcraft's maintenance checklist includes the drain pan and line and the drain-line heater every six months at least, and the preventive maintenance schedule shows where that fits.