Invaluable Freeze Event Protection
USA Coil & Air has been marketing our patented, freeze-damage water and steam coil line for over 25 years under the name Sentry Guard™. Sentry Guard™ is a one-of-a-kind invention that guarantees that any water or steam coil will not have freeze damage during a freeze event.
What is a “freeze event”?
Freeze events occur when chilled water, hot water, or steam heating coil has liquid in the tube core, little to no water velocity, and the air passing across the coil is less than 32 degrees F.
Inadequate freeze stats, fan & motor stop cycling off, pump malfunctions, valves close or dampers stay open, and many more. In essence, whatever mechanically keeps liquid in a coil while freezing air is blowing across the fin surface.
What happens to a coil when freeze damage?
Many think that freeze damage comes from ice expanding and creating a hole in the tubes or return bends. Ultimately, the pressure increase is the real culprit and occurs when the internal pressure builds inside the coil until the weakest part bloats and fails in the middle of the bloated area.
Where is the so-called weakest area of the coil core?
Many times, the weakest area is at the return bends. The formation of a bend during the manufacturing process may have stretched the tube’s outer wall – making it slightly thinner than the tube wall. This area can also be thinner due to water erosion going around the bends.
Tubes can also burst due to ice forming in the tube while the freeze action is taking place. The ice containment creates an increase of pressure within the tubes that will not allow the pressure to build up to reach the bend on the end of the coil, causing return bend damage.
How does USA Coil’s Sentry Guard™ burst-resistant line work?
In the ’90s, USA Coil’s tests and data proved that freeze damage was a pressure event versus an expansion of ice. With that in mind, we developed and began fabricating “Freeze-Relief Plugs” that relieve the internal pressure before catastrophic damage to the coil can occur. These freeze-relief plugs are installed on return bends and headers and protect the tubes and bends from freeze damage.
How do I place a Sentry Guard™ coil back in place after a freeze event?
Check all the freeze relief plugs, screw off the plugs that had membrane failure (which saved the coil), and screw on the new plugs you would keep in stock. If you need new plugs, you can order them from USA Coil as “overnight delivery.”
What is the added cost for the Sentry Guard™ design?
For one and 2-row heating coils, approximately 30%, and for chilled water coils, about 40-60% based on rows and circuitry. In some areas of the country, chilled water coils often receive freeze damage because they operate during the winter months, and many of these coils do not have circuits and drains that allow the entire coil to be drained for winterization.
What types of facilities need Sentry Guard design?
USA Coil has added or replaced thousands and thousands of coils over the last few decades. Any facility with outside air introduced into HVAC or process air application can benefit from this revolutionary design. They include hospitals and medical buildings, schools and universities, public places like arenas, airports, and railroad terminals. Replacement also occurs in pharmaceutical, high technology, food or beverage, and manufacturing industries. Ultimately, when there is the critical system downtime, it will be expensive in dollars, time, and customer goodwill. For example, an operating suite in a hospital can cost 100K to 150K per day in lost revenue. Sentry Guard™ is worth every penny!
Why leave your essential HVAC systems vulnerable to a costly freeze event?
Sentry Guard™ coils will last for 2 to 3 decades and give you the peace of mind that there will not be catastrophic damage due to a simple mechanical malfunction. We sell these coils for new applications, and we can also have them installed in almost any air handler – no matter the manufacturer – or as a replacement that matches an existing coil design.
Take advantage of USA Coil & Air’s 40+ years of knowledge and experience to assist you in making the right selections. We solve problems for our customers – not create new ones. Our SENTRY GUARD™ Burst Proof line of steam heating coils prevent damage from a freeze event. There are many systems where you cannot locate the trap below the coil outlet or have other problems that might cause these coils to go into a freeze event. SENTRY GUARD™ is your answer.
