Even a small gap in a cooler or freezer frame creates a cascade of refrigeration problems that compounds quickly. Warm, humid store air finds the path of least resistance into the case, and once it gets in, it condenses or freezes on cold interior surfaces, forces the evaporator to work harder, raises product temperatures, and drives up energy costs.
The Anthony installation and troubleshooting guidelines identify air infiltration as a root cause of ice buildup, condensation, and poor sealing performance across their cooler and freezer door systems. The tolerance they specify for acceptable gap size is strict: no more than one-eighth of an inch between the frame and the refrigeration box.
That threshold matters because of how quickly infiltration scales. A gap larger than one-eighth of an inch doesn’t just allow a little more warm air in, it creates enough space that silicone sealant can’t bond correctly across it, insulation won’t sit flush, and the frame may twist when hardware is tightened. Trying to seal over a gap that’s too wide without correcting the underlying geometry first will not stop infiltration and may mask the problem long enough for more serious damage to occur.
Where air leaks actually appear
Most leaks occur at the frame perimeter, particularly between the frame and the refrigeration box, at frame joints, and around electrical conduits that penetrate the case. Improperly sealed insulation is another consistent source, especially in low-temperature and high-humidity applications where moisture works its way through gaps over time. If frost consistently forms in one location inside a freezer, the leak is usually located directly above that point; cold air is escaping in one direction and warm air is being drawn in at the leak site.
Gaps form through several different mechanisms. Frames installed without adequate shimming are one of the most common culprits, particularly when a case isn’t level to begin with. Vibration and the thermal cycling of repeated heating and cooling cause components to shift and expand over time. Insulation that was never fully seated during installation may shift further after the case has been in operation for months or years. Wear on gaskets or hinge mechanisms can pull the door out of true and create secondary gaps at the perimeter.
How to detect an air leak without specialized tools
A smoke stick held near the frame is the most direct test: if the smoke moves toward the case, air is leaking in. A flashlight test achieves the same result differently – shining a light from behind the suspected area reveals any gap the naked eye might miss. Frost pattern mapping is useful for localizing a leak that’s already developed: the ice formation tracks the path of the warm air that created it. In all cases, a cold draft felt near the frame or mullion during normal store hours is a reliable early indicator that something isn’t sealing correctly.
Correcting a frame perimeter leak
The Anthony specifications are clear about the correct sequence. The gap must be brought within the one-eighth-inch tolerance first, using shims, before any sealant is applied. Once the frame is shimmed and confirmed square and plumb within one-sixteenth of an inch, the correct sealing material is RTV 108 NSF-approved food-grade silicone, applied to both the inside and outside of the refrigeration barrier. All joints and seams must be fully covered, and in low-temperature or high-humidity applications, encapsulated insulation must be present throughout the perimeter. Applying silicone to a gap that exceeds one-eighth of an inch without shimming first will not create a durable seal regardless of how much material is used.
Conduit penetrations deserve separate attention. Even small gaps around electrical conduit entries introduce significant moisture into freezer cases, and they’re easy to overlook because the conduit itself appears to be filling the hole. The correct approach is to inspect each penetration for gaps, apply RTV 108 continuously around the entire circumference, confirm the seal is airtight, and check for any wiring movement after sealing that might compromise the new seal over time.
When a fixed leak comes back
If leaks reappear after being sealed, the problem is almost always structural rather than a sealing failure. The frame may never have been squared correctly during installation. The box may be shifting due to floor settling. Insulation may have been installed incorrectly and is continuing to move. Damaged or missing mounting hardware may be allowing the frame to flex under normal load. In these cases, a fresh bead of silicone won’t hold. The repair requires a more thorough inspection and possibly reinstalling the frame from the beginning.
For cooler and freezer door parts, gaskets, and replacement hardware for Anthony International systems, Supermarket Parts Warehouse stocks components with same-day shipping on orders placed before 10am. For new door selection or a full frame specification, see Anthony International doors through KCL or the walk-in cooler and freezer door selection guide.
Frequently asked questions
How do I know if my cooler or freezer has an air leak?
Look for frost, condensation, cold drafts near the frame, or smoke movement toward the case when you hold a smoke stick near the perimeter. Any of these indicates infiltration.
Can I seal a gap larger than one-eighth of an inch with silicone?
No. The gap must first be reduced to within one-eighth of an inch using shims. Larger gaps won’t seal reliably regardless of the sealant used.
Why does frost form in just one spot inside the freezer?
Frost accumulation tends to occur directly below the point where warm air is entering. The air infiltrates at the leak site, rises as it cools, and deposits moisture on the first cold surface it contacts above the leak.
What sealant does Anthony specify for cooler and freezer frames?
RTV 108 NSF-approved food-grade silicone, applied to both the inside and outside of the refrigeration barrier at all joints and seams.