Desaturation Coils

They feel that clammy, stuffy air, even when the AC’s blasting? Or even worse, stepped into an establishment with air filters that resembled a moist sponge, teeming with things that ought not to be there? If you’re nodding, however, you’re in the right place to get the lowdown on Desaturation Coils. These aren’t just another thing to throw on your HVAC or features list; they’re your secret weapon against stubborn damp that icky-humidity creates, and the fun things that grow from it, especially in situations where your customers literally can’t even with that, like a hospital or a lab.

Well then – what are Desaturation Coils? Put simply, they are an intelligent, all-in-one system that both cools, dehumidifies, and then gently reheats the air in one, highly integrated unit. The goal? Get rid of that kind of damp, saturated air that is going to potentially cause you problems, downstream, in your air handling unit. Think of it as a cooling coil with its own internal ‘reheat’ zone, cradling the stream of air with a gentle kiss of warmth immediately after it’s been chilled. It’s engineered to make sure the air leaving your system is not only cold, but also correctly dry, preventing condensation issues and a load of associated problems.

Deciphering the Air Game: The Case for Disruption Coils

Before we go any further, let’s get our air and moisture situation squared away. No corporate jibber-jabber here, just the straight talk.

Think of it like this:

Dry bulb temperature: This is the bare temperature as you read it on a normal thermometer — how warm or cold it actually feels. It’s your basic comfort indicator.
Wet Bulb Temperature: This one’s a little trickier. It’s the temperature that air would have to be cooled to in order to remove enough water for it to become completely saturated. It informs us about how much moisture the air is still able to carry.
RH (relative humidity): You know this one. It’s the percentage of moisture the air at that moment is holding relative to the absolute maximum it could hold at that particular temperature. A high RH is a lot of moisture.
Saturation: When the air is actually holding all the water vapor it can at a given temperature; this is 100% Relative Humidity. Imagine a sponge that’s fully saturated.
Dew Point: The temperature at which moisture begins to condense from the air. If your air gets to this temperature, you are getting condensation — as in water droplets.
Relative Humidity: This is this actual amount of water in the air, compared to the maximum amount it could hold, based on temperature. When it comes to humidity is a more accurate way of measuring humidity than RH.
Sensible Heat: The heat which you feel or “sense”. It so instantly lowers the air’s dry bulb temperature.
Latent Heat: This is the heat that goes into a phase change, like water vapor becoming liquid condensate. It does not affect the dry bulb temperature so you cannot “feel” it, but it is essential for dehumidification.

Now here’s the issue that many facilities have to deal with: When you cool air down for comfort or for design reasons (such as in an operating room) especially to very low temperatures, you are bound to hit that dew point. As the air comes out your standard a/c cascade coil it can be 100% saturated. What happens next? If there are downstream components, such as filters or even ductwork, the smallest pressure drop only allows even more water vapor to collapse out of the air. This results in filters soaked with water, an environment ripe for mold and biological growth, and a host of maintenance nightmares. Traditionally, this has translated to adding a supplemental reheat coil (more piping and hot water) or moisture eliminator plates (additional air pressure drop). Nobody wants that.

The Mechanism in Detail: The Way Desaturation Inductors Work

So, what is the Desaturation Coils’ solution for such moisty conundrums? It’s pretty elegant, actually. Think of a traditional cooling coil with a smart spin. This coil isn’t a mere block, but more along the lines of 2 distinct coils cleverly integrated into one housing.

Here’s the cheat code:

The Cooling Core: The warm, wet air strikes the main cooling area of the coil first. This is where the cold water goes to work, extracting both sensible heat– which lowers the dry-bulb temperature — and latent heat (it turns water vapor to a liquid) from the airborne water vapor. The air becomes chilled and much of its moisture is wrung out as condensate.
The Reheating Core (The Secret Sauce): The cool water absorbs some heat from the air as it travels through the cooling core and warms up a bit. Rather than merely re-circulating this “used” warmer water directly back to the chiller, a Desaturation Coil features an “integral re-heat loop” – essentially one or two additional coils rows along the leaving air side.
The Gentle Lift: The slightly warm return water from the cooling section, meanwhile, makes a pass through these last rows, providing the freshly cooled (and possibly saturated) air with a gentle lift in sensible heat. We’re back to raising the air temperature only a few degrees — typically from 1.5° to 3.0°F.
The Magic Happens: This slight warming in temperature is sufficient to elevate the air off the point of saturation and reduce its relative humidity to a moist 90-92% instead of a soggy 100%. You get cold air that is no longer saturated, or condensing on your filters or in your ductwork downstream.

It’s a smart, self-contained process. No need for extra piping, no individual controls for reheat. The coil relies on its warmed-up water to perform the reheating, so it is much more efficient and effective.

Where These Bad Boys Really Stand Out: Best Uses

You are probably asking yourself “Alright, who even wants these Desaturation Coils?” They’re not for every casual comfort cooling rig. These coils are usually specified for systems that have the cooling coil as the last element in an air handler (High Air Temperature units) and applications requiring strict humidity control.

These are the ideal spots where Desaturation Coils can make a difference in the game:

Laboratories and Science/Research Facilities: These establishments generally maintain extremely high standards when it comes to temperature and humidity control. Enjoy delicate experiments or sensitive equipment: You don’t want condensation mucking them up.
Hospitals and Clean Rooms: In places such as operating ro oms, controlled air is not only a matter of comfort, it’s also essential for patient safety and to prevent cross-contamination. room Atladavik Wet filters or Bio Grow are just not a solution!
Any Critical Application: If your facility has an absolute requirement for extremely precise environmental control – such as high-end manufacturing or pharmaceuticals or certain archives –Desaturation Coils leap to the next level in micro-level control.
AHUs with “blow-through” configurations: This is a biggie. In such installations, the supply fan is located upstream from the cooling coils. This is because the heat that you just put in the air (from the motor of the fan) isn’t also added by the fan motor and can make it more challenging to get the air off of saturation. And that’s where the Desaturation Coil comes in – the bump in temperature you need. These can become serious in higher humidity regions if the final filters are located downstream of the coils – the filters are always wet.

They’re also great when paired with heat recovery solutions like energy wheels or heat pipes. If you are trying to recycle energy, you still have to deal with that last air component, and Desaturation Coils are an efficient way to get you there.

The Benefits: Why Your HVAC Upgrade is Desaturation Coils

So what’s the big gain of bringing Desaturation Coils on your roster? This is all about getting the most for the least amount of effort. Here’s why these coils are a good idea:

Cost and Energy Savings (More Bang for Your Buck)

Energy Smart: On both the air and water side, they run VERY efficient.
Power: They can save a lot of pump and fan horse power by including the reheat, since there is not as much pressure drop through the coil assembly than there is through separate coils or eliminator plates! Less strain on your motors, and you don’t spend as much on electricity.
No High-Temp Water Necessary: Unlike old-style reheat coils, which often require 180°F hot water, these coils use the lukewarm return water from the cooling process. This not only saves you the cost of more high-temperature water loops, but it also saves you energy running said water.

Better Air Quality and Health For Your System (Breathe Easy, No Really)

Goodbye Wet Filters: That is a huge score. No more constantly having to drain and replace Below-the-Floor Filters (BTFFs).
No More Mold/Biological Growth: A wet filter is the perfect environment for nasty bacteria. And by keeping them dry, you’re not only reducing the chances of mold and other biological contaminants but also creating a healthier line of defense to breathe in at your living and breathing spaces.
Prevent Water Carry-Over: Reheat section serves as a self-purging device to prevent water droplets from entering the duct work or further downstream equipment.

Simpler Installation and Maintenance (Fewer Headaches)

Two-in-One Design: With two coils in one, design, ordering and installation are all faster and easier. It’s fewer components to manage.
No Additional Piping/Controls: This is BIG. Forget the additional piping runs, or complicated control valves to reheat; it’s all within.
Space Saver: When you combine functions, Desaturation Coils maximize air handling unit space and can make servicing your equipment easier.
Keep Original Position: You only need replace it and keep the coil in the original place, save time, save the cost of the system change.

Designs to fit your needs (Your Specs, Your Way)

These coils are highly customizable. You can raise or lower the coil, select different fin patterns for maximum airflow and select from a range of materials depending on your unique air or water conditions. So the coil is precisely built to fit you!

Desaturation Coils: How Do They Stack Up?

When you’re looking for a solution, it’s always smart to compare your options. Desaturation Coils aren’t the only game in town for humidity control, but they offer distinct advantages.

Here’s a quick rundown of how they compare to some common alternatives:

Feature/Option	Desaturation Coils	Traditional Reheat Coil	Wrap Around Heat Pipe
Function	Cool, dehumidify, and reheat in one assembly.	Cools, then separate coil reheats.	Pre-cools and reheats via refrigerant loop.
Reheat Method	Uses return water from cooling coil.	Requires separate hot water supply (e.g., 180°F).	Passive refrigerant loop.
Piping/Controls	Single supply/return connection; no extra piping/controls for reheat.	Additional piping & control valves for reheat coil.	No additional piping/controls for reheat.
Installation	Integrated, simpler.	Two separate coils, more complex.	Can be complex to install due to size and routing.
First Cost	Generally moderate.	Moderate (for two coils).	Higher.
Life Cycle Cost	Good, due to efficiency and reduced maintenance.	Potentially higher due to extra energy for reheat water, maintenance.	Significantly lower over time.
Airflow Impact	Low pressure drop (reduced headers, optimized fins).	Can add significant air pressure drop.	Minimal air pressure drop.
Moisture Control	Excellent, raises air off saturation, eliminates water carry-over.	Requires careful balancing to avoid saturation; eliminator plates may be needed.	Excellent, effective dehumidification.
Temperature Lift	Typically 1.5-3.0°F.	Variable, depending on hot water supply.	Greater, 5-15°F.

Another common but often ineffective approach is to simply move cooling coils to a “draw-thru” position (downstream of the fan) to address humidity issues. While this might seem like a simple fix, it can be incredibly time-consuming, expensive, and sometimes just doesn’t deliver the results you need. Desaturation Coils provide a direct, more efficient answer without tearing apart your entire system.

Under the Hood: Tech Specs & Construction

O.K., a bit of the tech stuff, but I promise to keep it simple. A Desaturation Coil is not so much a plain, white box; but one that has been engineered to precision.

The Core Components: You’ve got your main cooling core, and that ingenious re-heating core, all built into a nice slick steel casing.

Sturdy – Material Matters:

Tubes: are usually copper [3/8”, 1/2”, or 5/8” OD], though they can be CuNi, Stainless Steel, Carbon Steel, or AD Brass depending on fluid and ambient conditions.
Fins: These are the surfaces that carry the heat away. You’ll find them in aluminum, copper, stainless or carbon steel — and often with specialized patterns: some have names like Sine Wave, New Ripple, Flat, Louver, or Lance, all engineered to maximize the passage of air and heat.
Casing: The outer shell that protects everything, typically constructed from galvanized steel, stainless steel, carbon steel, copper, aluminum, or brass.

Circuitry: The Flow Path This is the way the water moves through the tubes, how many times the water crosses the air stream, so how many times it gets cooled. Then they are various other type of circuit like Quarter, Half, Three Quarter, Single, One and one half, Double, Triple or Bespoke. Ideally the warm air is counter-flow with the warmer separated water, which is the most efficient arrangement.

Smart Connections: One of the nicest things about them is usually they require a single supply and return connection. This can happen because the reheat loop inside only takes the return water of the main cooling section. And with a few models, you’ll find no headers on the backside of the coil due to extended return bends that can reduce water pressure drop by as much as 50%, resulting in less effort for your pump.

Rows: Available in multiple depths from 1 to 12 rows, and can be customized to achieve the desired results. An illustrative example would be a 10-row cooling unit followed by a 2-row reheat unit.

Quality Assurance: A manufacturer that you can trust, we ensure that every coil are tested to specifications at ARI and meet the set certifications including but not limited to UL 207 and Intertek – ETL Semko. Which is to say: They’re made to do stuff.

Real-World Win: The Tale of the Shands AHU-19

Let me tell you about a case when Desaturation Coils truly dried up a big problem!

Picture Shands Healthcare in Gainesville, Fla. They had this big air handling unit, AHU-19, running 156,000 cubic feet per minute of air. It was a “blow-through” style, with the cooling coils prior to the supply fan. It wasn’t the most efficient system; in a wet climate like Florida, air filters at the end of the line downstream from the coils were always damp.

You can be sure how it played out next:

Issue: Moist filters resulted in too much pressure drop, causing the system to have to work overtime. They died young too as measured in years, so they had to be replaced often at high cost. And the kicker? Filters wet with water are a medium in which biological organisms grow. Not a great look for a medical center, right?
Discussion: The solution: Desaturation Coils. Instead of ripping the whole system out or attempting to add in complicated external components, some of these integrated coils were installed. They are basically just normal chilled water coils, with those clever extra rows on the leaving air side and being internally piped to pass the warmer return water through them.
The Result: This slight alteration enabled the warm return water to easily raise the leaving air temperature a couple degrees above its saturation point. This little change was a game-change. The filters dried up, the extreme pressure drop disappeared, and the vicious cycle of replace and then have possible bio-growth ceased.

Better still, the installation was accomplished without significant disruption. They even managed the last tie-in during a time of economizer cooling, reducing downtime. This was not just a patch, it was a total solution, inexpensively bringing desired temperatures and humidities back to the home.

Good Luck: Desaturation Coils to the Rescue for Your Humidity Issues

So here it is in a nutshell for Desaturation Coils: They’re a hardy, smart solution to dealing with tough moisture problems in critical facilities. They make dealing with condensation, protecting your filters, and just generally having your air handling unit perform like a boss, a breeze.

It’s not only about the temperature, it’s about clean, dry cool air and how it can provide for your need in multiple uses for use in the shop or anywhere you have water damage or moisture control issues. Wheter you’re fighting a difficult blow-through system, or just looking for the cleanest air possible, these coils are the quickest way to a healthier, more efficient, less troubled HVAC system. They’re a true game changer when you need to do some low temperature air stuff — especially if you have access to low temperature water and they give the boot to those pesky water droplets by partially reheating the air just above saturation.

Telawell: Your Custom Heat Transfer Solution Provider

At Foshan Telawell, we’re not just about components; we’re about solutions. We specialise in the intricate world of designing, manufacturing, and rigorously testing custom heat transfer products tailored for a vast array of industries. As a premier OEM, we pride ourselves on offering a comprehensive portfolio of heat exchangers. This includes everything from finned tube and plate heat exchangers to robust spiral fin tube and resilient stainless steel coils. Our expertise also covers condensers, evaporators, and diverse water coils, ensuring we can meet your specific thermal management needs.

What Sets Telawell Apart – Our Key Strengths:

Bespoke Customisation: We don’t do “off-the-shelf” if it’s not the perfect fit. Our strength lies in crafting solutions precisely aligned with your unique requirements.
Diverse Product Arsenal: Whether you’re dealing with steam, hot water, tricky refrigerants, or other heating and cooling mediums, we have the product and the know-how.
Deep Industry Expertise: Our solutions have found homes in demanding sectors including fossil fuel and nuclear power, heavy industrial applications, automotive, petrochemical, and sophisticated HVAC systems. We speak your language.
Cutting-Edge Manufacturing: Our facilities are equipped with state-of-the-art machinery, ensuring every product meets stringent standards for precision and quality.
Seasoned Engineering Minds: Our experienced engineering team isn’t just about parts; they’re about optimal heat exchanger selection and intelligent application, guiding you to the most effective solution.
Unwavering Focus on Quality: Customer satisfaction is our north star. This is underpinned by standardised management practices and a commitment to continuous improvement in everything we do.

Telawell is where technical mastery meets exceptional service and competitive pricing. We’re dedicated to providing a seamless experience, from your initial enquiry right through to delivery and beyond. Our mission is simple: to deliver efficient, economical, and robust heat transfer solutions that don’t just meet your expectations, but consistently exceed them.

Our Manufacturing

Frequently Asked Questions (FAQ)

Q:What is the first problem a Desaturation Coil addresses? A: It is mostly designed to prevent air from coming off a cooling coil 100% saturated (saturated meaning at 100% relative humidity) where if something down stream like a filter got wet (or wet enough) that the filter support would grow something biological and require costly, continual ordering of replacement filters that could have been solved by the addition of the RAP.

Q: How do Desaturation Coils save on power? A: They are energy-efficient since they leverage the warmed return water from the cooling operation for reheat, actually relieving the need for a separate hot water supply (like 180ºF water) and associated piping and controls. And they can decrease pump and fan horsepower on account of lower overall pressure drop.

Q: Can I use a Deactivation Coil on my air handler? A: They can be very effective but are especially effective in last position of the air handler unit leading to the outside or in a “blow through” design which has the supply fan before the coils and when tight humidity control is required.

Q: What is a Desaturation Coil as compared to a Wrap Around Heat Pipe? A: The Desaturation Coil performs cooling and reheat in a single assembly (reheat is accomplished by running heating coil water through the cooling coil resulting in some of the cooling being negated, to raise the air tem l-3°F) where-as the the Heat Pipe Wrap Around does both pre-cooling upstream of the main cooling coil and significantly more reheat (5-15°F) downstream from the coil through another passive refrigerant loop. Heat pipes generally have relatively larger first cost and smaller life cycle cost.

Q: Where are Desaturation Coils typically found? A: They are usually used in locations that have stringent environmental controls, such as hospitals, clean rooms, science and research labs and other critical applications that require consistent temperature and humidity.

Q: Does the Desaturation Coil require additional piping for reheat? A: No, that’s one of their major virtues! The reheat is internal to the coil using return water from the cooling part. This eliminates the need for any extra piping, control valves or electrical involving the reheat section.

In the end, the Desaturation Coils should prove to be a wise investment for the homeowners seeking to be rid of moisture problems and interested in ensuring the air management systems run free and clear.