Coils and Counter-flow: 5 Common Questions

1)  Coils and counter-flow?

The first thing to remember about coils and counter-flow is that chilled water coils are always built to be piped in counter-flow. This means that the air flows in the opposite direction as the water. For example, with counter-flow, the air flows through rows 1-8, while the water runs through rows 8-1. Water always travels through the coil in the opposite direction of the air; hence the term “counter-flow.”  Direct Expansion Coils (Evaporator Coils) are also piped in the same manner.

With that said, what happens when you do not pipe cooling coils counter-flow? Almost all coil selection programs you will see or use will be based on counter-flow conditions. If you opt to not counter-flow a chilled water coil, you’ll have to reduce the coil’s overall performance by a certain percentage. That percentage reduction varies based on each coil’s unique dimensions, but a reliable estimate is a loss of 8-12%. Simply piping the coils in the correct manner from the beginning would seem to be the easiest and most cost-effective solution.

2)  Why do you feed from the bottom of the coil?

DX Coils

You always want to feed a water coil from the bottom connection so that the header fills from the bottom on up and feeds every tube connection evenly. All tubes must be fed evenly with the same amount of water. If you try to feed the header from the top, you greatly increase the risk of “short circuiting” the coil and having a higher water flow through the top tubes in the coil.

3)  What is a Water Hammer in a Steam Coil?

On a long Steam Coil, you will be hard pressed to get the steam through the length of the coil. Slowly but surely, that steam converts into condensate, which is pretty much the worst thing that can happen to any system. If not evacuated, the condensate just lays in the coil when the system is shut off. This problem comes into play when the steam is turned back on and meets the condensate laying inside the coil. In addition to the noise, the steam and condensate cause huge amounts of additional stress on the coil’s joints. As a result, over time, your coil will inevitably fail.

4)  What else happens if you do not evacuate condensate?

When you cannot or do not evacuate the condensate on long steam coils, the condensate ends up blocking the steam. A steam coil should never feel cool to the touch, but when condensate blocks steam, one part of the coil will be warm while the other will be cool. Again, that should not happen. Steam coils are interesting in that they are more dependent upon the system and installation than any other type of coil. A steam coil must be pitched to the return end of the coil. Obviously, steam is not water. Traps, vacuum breakers and other steam accessories must be installed and located properly for the system to function.

5)  Is it necessary to pipe steam and/or hot water coils in counter-flow?

Simply put – no! Circuiting a coil is only necessary to ensure the connections are on the side of the coil that you want. The rows and tubes in the coil dictate how and where you feed, but the steam supply always needs to be the high connection. This method ensures that the leaving condensate is on the bottom of the coil and below the lowest tube within the coil. Whatever else you do, know that the condensate must leave the coil!

If you have any questions or need assistance with ordering and/or installation, please contact a sales engineer at Capital Coil & Air. We will walk with you step-by-step through your entire project should you require any assistance. CALL OR E-MAIL US!  We look forward to the opportunity to work with you on your future projects.

 

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OEM Replacement Coils: Repair or Replace

When considering OEM replacement coils, there are multiple reasons why coils can fail prematurely. Sometimes, OEM Coils simply freeze and can never be repaired. Other times, the coil was selected incorrectly, which in turn, made the coil significantly underperform. Many times, there is substantial corrosion or something else in the system that causes the coil to fail. However, most coils, when selected correctly, and in systems that are properly maintained, can last anywhere from 10-30 years!  10-30 years is also a pretty wide range, and there are many variables in how long you can expect a coil to perform. Factors, such as ongoing maintenance, air quality, and water/steam quality all have an effect on a coil’s lifespan.

OEM Replacement Coils

Reasons Why Coils Fail Of Old Age

  • While the coil’s tubes are considered the primary surface, 70% of all coil performance is performed by the finned area on a coil, which is known as the secondary surface. The fin/tube bond is easily the most important manufacturing feature in any coil. Without the bond between the tubes and fins, the coil could never properly function. Like all things however, over time the fin/tube bond becomes less efficient with constant expansion and contraction. While the construction of the coil, as well as the fin collars, does not allow the fins on the coil to move, that fin/tube bond naturally weakens a coil’s life over time after installation. Because of this, it is not a stretch to say that a coil is easily 30% less efficient after (20) years.
  • Cleaning coils often pushes dirt to the center of the coil, and this occurs even more so on wet cooling coils. Just remember that coils can become great air filters if not properly maintained. The BTU output of any coil is in direct proportion to the amount of air going through the coil. If you decrease the CFM by 20%, you are also decrease the BTU’s by 20%!
  • Cleaning agents often corrode aluminum fins. Since every square inch of fin surface matters in performance, corrosion of the fin surface is always detrimental to the coil’s performance.
  • Many times, there are coil leaks simply because of old age. No coils are immune to erosion. You might find the brazing in the tubes, as well as the brazing in the header/tube connections failing over time. Steam can be both erosive and corrosive under higher pressures. Water travels through the coil at 2 – 5 ft/second, so erosion is an enormous part of coil failure, regardless of how well-maintained. Erosion is always there, whether you realize it or not.
  • Water/steam treatment and the corrosive effects of bad steam/water can all be causes of coil failure…which then necessitates the need for a reliable manufacturer for OEM replacement coils.

So What Is The Solution?

Some coils can last 5 years, and some coils can last 30 years. As you have read, there are numerous factors that contribute to a coil’s life. In the end, there will most likely have been multiple attempts to repair that coil to make it last as long as possible. The depressing news is that most of these “Band-Aid” attempts do not work well. The most likely outcome is that you are buying a new coil anyway, so why waste the time and money on a temporary solution?

Coil failure is a “pressure event”, which is a fancy way of saying that a coil is leaking. We’ve listed some of the most common repair methods that you are likely to come across:

  • Drop leaking tubes from the circuit: Keep in mind however that every dropped tube reduces the coil’s performance by triple the surface area of the tube that is dropped. Again, while ok in the short-term, this is simply another “Band-Aid” fix. Over time, your energy costs will rise exponentially, and you will probably end up buying a new coil anyway.
  • Braze over the existing braze: As mentioned above, erosion has caused the original braze to fail, so all that you are really doing is pushing the pressure to another braze, which will then begin to fail as well.
  • High Pressure Cleaning: This method bends the fins, further restricts the airflow, and pushes dirt more to the center of the coil, which can never be adequately cleaned.

The real reason why coils need to be replaced rather than repaired is due to energy costs. If your coil is not operating near desired levels, you’ll need to increase the energy to make it work at its peak performance. Energy increases might be slight at first, but they are guaranteed to continue to rise over time. For example:

  • Somebody adjusts the fan drive for higher speeds, higher CFM’s and higher BTU’s.
  • Someone adjusts the boiler; the water and steam temperatures are higher.
  • Someone adjusts the chiller (1) degree higher for colder water to the chilled water coil.

Whichever method is used, performance begins to suffer and adjustments to the system occur. These adjustments cost energy efficiency and ultimately, money!

If you have ever experienced repairing a coil, then you know it is labor intensive and typically will not work as a permanent solution. With very few exceptions, repairs should be seen as nothing more than temporary until you’re able to replace that coil!

Capital Coil & Air has seen every “repair” method used, as well its inevitable outcome, so instead of putting yourself through that, call Capital Coil and allow us to be your coil replacement experts.

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Case Study: We Need These Coils on a (5) Day Quick-ship

In late June, Capital Coil received a call from a Trane office in Ohio regarding quick-ship availability. One of Trane’s top customers had an urgent need for (12) large chilled water coils with stainless steel casing. The problem/hurdle that they were encountering was that they needed all (12) coils to be built and ship out of the factory in (5) business days. Completion of the whole project was 100% contingent on them receiving the coils in their specified time-frame. An additional complication was the fact that July 4th was the following week, and they needed to have the coils ship prior to the holiday.

Trane shopped the project around to different manufacturers, but not one could guarantee to ship in (5) days. Some manufacturers waffled and claimed that they could have them built in (6) or (7) days, but not one could guarantee to ship in (5) days. A sales rep in that same Trane office, who had worked with Capital Coil previously, suggested that his co-worker reach out to us to see what we could do. After speaking with Trane’s project manager, we immediately contacted our head of production to make sure that we had the capacity to complete all (12) coils in the required (5) days. She assured us that we had the materials and manpower on-hand to get them all built and ship on time. We agreed to accept the project and began work on the coils immediately.

Due to the size of the project, as well as it’s time-sensitivity, we had multiple calls daily with our factory to ensure that everything was proceeding on schedule. We then gave Trane daily status updates, so they were constantly informed of everything from the brazing of the coils to entering the final testing phase. Chilled Water Coil

As promised, all (12) coils were built correctly and shipped out in the required (5) days. Our logistics team was then in constant communication with the freight company to make sure that the delivery was on schedule. And just like during the production phase, we passed daily tracking updates along to Trane, so they knew where their coils were at all times and when they could expect delivery. All (12) chilled water coils arrived on July 3rd with zero freight damage, and the project was completed on time!

A company as large and influential as Trane can have their coils built by anyone, but Capital Coil was the only manufacturer that could guarantee to have their coils built and shipped by a required date. Additionally, in working so closely with Trane throughout the whole process, they were kept up-to-date in real time from the start of production to final delivery.

Capital Coil offers a level of service that you won’t get with other manufacturers. When we guarantee to ship by a certain date, we stand by that guarantee, or you do not pay!

 

Trane’s project manager’s comments to Capital Coil upon completion/delivery:

“This will help us get a jump on this project prior to the big event taking place next week! 

I will make sure to share your information with others across our great lakes region about our experience with your company, so that they know we have THIS option to go to for our coil needs. THANK YOU ALL!!”

Guidelines For Air Velocities

The height, length and resulting air velocities greatly figure in everything in determining the size and performance of a coil. Step # 1 in determining the size and performance of a coil is dependent upon understanding face & air velocities of air across the coil. Whether you use CCA’s coil selection program to help size the coil, or you are replacing an existing coil; the height, length and resulting velocity determine everything.

Hot Water Booster Coils

air velocities

Every coil has a specific, optimum velocity, so you want to make sure you are within 30% (+ or -) of that number. For example, booster coils have an optimum velocity of 800 ft/minute. That means that you can drop your velocity to 600 ft/minute, or conversely, increase the velocity to 1,000 ft/minute. The duct velocities are almost always higher, which means that you will need to transition to a larger coil. Try to get to as close to 800 ft/minute as possible, while sizing your coil to make the transition as easy as possible. Everything with coils is a balancing act.

Hot Water & Steam Coils

Like booster coils, hot water and steam coils should also have face velocities at approximately 800 ft./minute. Both steam & hot water coils have only sensible heating, which is why their face velocities can be the same. Face velocities ultimately control the coil’s cost, so 800 ft./minute really is a heating coil’s “sweet spot”.

If you are purchasing an air handler unit, oftentimes the heating coil is smaller than the cooling coil because the face velocities on heating coils can exceed those of cooling coils. Due to water carry-over, cooling coils cannot exceed 550 ft/minute, while heating coils only deal with sensible heat.

Chilled Water & DX Coils

Due to the limited face velocities of cooling coils, your choices are more limited. With cooling coils, your face velocity must be somewhere between 500 ft./minute-550 ft./minute. Remember that when dealing with cooling coils, you are dealing with both sensible and latent cooling, so the coil is wet. When you exceed 550 ft./minute, water carry-over occurs past the drain pans.

If you are purchasing an air handler unit, you probably will not have worry about the coil’s face velocity as most coils come pre-sized at the acceptable face velocities. Fan coils also come pre-sized with the correct CFM’s. However, if you are replacing an existing cooling coil, the face velocity must remain at or below 550 ft/minute!!

 Air Stratification Across The Coil

Air does not travel equally across the face of a coil. If you were to divide a coil into (9) equal sections, like a tic-tac-toe board, you would see a high percentage of air travelling through the center square, rather than the corner squares. In a perfect air flow scheme, 11% of the air would travel through each of the 9 squares, but that is not what happens. Because more air travels through the center of the coil, you want to avoid putting a fan too near the coil. Due to central air flows, most systems are draw-thru, rather than blow-thru. This is also why you want to avoid installing your coil near any 90 degree angles/turns in the ductwork. Avoid any situations that contribute more than the “natural” air stratification to help ensure your coil is at maximum efficiency.

In some situations involving cooling coils, you will have water carry-over even when the coil is sized correctly. How can this happen? Think about the tic-tac-toe board again. Air velocities are exceeding 700 ft./minute in the coil’s center, while the corners are around 300 ft./minute. This cannot and will not work.

Coils do not have any moving parts. They simply react to the air across the outside of the coil and whatever is running through the inside of the coil. Coils are 100% a function of your entire system, as well as the installation in general.

Capital Coil & Air is here to help with any coil selections that will help avoid costly missteps that lead to wasted time and money. Call us on your next project, we greatly look forward to working with you!

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5 Work Day Quick-Ships on HVAC Coils – Why Capital Coil does it right

Day 1 – 38% of all orders sent to Capital Coil are on some kind of quick-ship, whether it be on a (5 day, 10 day, or 15 day). We enter the order immediately so that all departments in the plant have the project in their systems and are ready to move on it right away. The coil isQuick-Ships engineered, routing sheets are sent to the shop floor, and everybody now knows what needs to be built. 

Day 2 – Sheet metal casings are cut and sized, headers and connections are fabricated, while tube sheets are fabricated.

Day 3 – All tubing and fins are cut, stamped and assembly begins. You can see what the coil will look like upon final assembly at this point. Coils can be seen sitting on assembly tables.

Day 4 – Tubes are then expanded into the fins, and keep in mind that this is not a short process. Headers are then brazed to the tubes, and if there are return bends, they are connected. The coil is completely assembled and moved to the testing tank. The coil is tested under water for 20 minutes at 550 PSI. About 3% of coils have small leaks someplace in the brazing and are sent back to braze again.

Day 5 – The coil is crated and sent to shipping for routing to the customer. Then most importantly, your coil will be shipping in the guaranteed (5) days.

As you can see by this description, with quick-ships, there is not a lot of room for error in the timing and shipping with OEM HVAC replacement coils. We’ve been doing this for a while now, and we’ve had an approximately (97%) success rate fulfilling all quick-ship requests. We offer quick shipments 365 days per year, with both (10) day shipments & (15) day shipments also available for lower premiums.

diagram 

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Why Are Fin Designs On HVAC Replacement Coils Important?

Replacement HVAC Coils

At first glance, fin designs on HVAC replacement coils seem about as exciting as watching grass grow. “Why would I ever care about fin designs on any coil” was probably your initial response to our question. Nevertheless, we would not dedicate a newsletter to this subject if fins were not important.

One of the primary reasons fins are so important is that you want to keep your coil as clean and maintained as possible. In order to properly maintain your coil, you need to have an understanding as to how HVAC replacement coils are constructed. While fins do not look like much, they are MUCH more complicated than what you can observe at the entering or leaving airside of the coil.

To begin, fins are responsible for a surprising 65% – 70% of the heat transfer on any coil, while tubes are responsible for the remaining 30% – 35%. Additionally, in order for your coil to work at optimum performance, you need to have a terrific fin/tube bond, (which we will discuss below).

  1. Fins are known as secondary surface, while tubes are referred to as primary surface. While this may seem counter-intuitive, the secondary surface is responsible for twice the amount of heat transfer as the primary surface.
  2. There are special dies (see picture) that stamp out aluminum or copper fins with the correct thickness, height, and depth to make the coil the correct size. For example, a coil might be 36” (height) x 96” (length) x (8) rows deep x 8 fins/inch.
    1. Fin Height: 36”
    2. Fin Depth: 12”, (8) rows deep
    3. # of fins in the coil: 768 (8 fins x 96”)
  3. Each fin has 192 holes stamped in the fin for 5/8” OD tubes (8 Rows x 24 Tubes), and each fin is identical.
  4. Each hole has extruded metal, which is more commonly referred to as the fin collar. The collars are sized to self-space the fins and allow for later expansion of the tube into the fin collar. This practice is also known as “bonding” and is essential to having your coil run efficiently/correctly.
  5. Each fin is rippled at the entering and leaving edge of the fin to help create air turbulence.
  6. Each fin is corrugated in the direction of airflow to allow for greater air turbulence. This is important to remember because turbulence creates heat transfer.

So again, what is the point of understanding the importance of fins in HVAC coils? While coils can be built with flat fins for various reasons, the vast majority of coils are built with enhanced fins. Enhanced fins help to ensure that the airflow is not running straight through the coil.

Regardless of fin type, keep in mind that HVAC coils can and will act as great “filters”. The tubes are staggered and not in-line; while the fins are designed to help break up the airflow and not facilitate an easy, straight-through air path. Dirt and/or other particles in the air get caught easily, which again, is why coils can act as great filters. Additionally, coils with more rows will usually get dirtier than coils with less rows. Lastly, chilled water or DX coils are typically wet coils, which results in them catching virtually everything in the air.

The amount of BTU’s through any coil is in direct proportion to the amount of air through the coil. For example, if you are only getting 90% of the design air through the coil, then you are only getting 90% of the BTU’s.

Coils require good filtration and periodic maintenance. If not done correctly, you’ll pay the price of higher energy costs on an inefficient coil.

By now, you have hopefully come to the realization that HVAC coils are much more complicated than they appear, and that fins are an integral part of the coil as a whole. Again, while admittedly not the most exciting topic, understanding the role and importance of fins in HVAC coils cannot be overstated. Capital Coil & Air is here to help you with any and all coil selections, and we look forward to working with you on your next project.

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Different Types of Steam Coils

There are two types of steam coils:  standard steam coils, which are used in most reheat applications, and steam distributing coils, which are used in applications where the entering air temperature is below 40 F degrees.  Many times, this type of coil is also known as a “non-freeze” coil, but that name is misleading because in reality, there is no such thing as “non-freeze”. 

Standard Steam

Standard steam coils operate a lot like hot water coils, but the construction is very different even if the coils appear to be constructed the same.  The supply and return connections are often on the same end like a hot water coil.  But, steam is very different than hot water, and the coil must be built for and circuited for steam.  Keep in mind that steam is always more erosive than hot water.  The brazing and tube wall thickness must account for steam. ALWAYS remember that even low pressure steam is more erosive than hot water, and a steam coil needs to be built accordingly.

Steam Distributing (Non-Freeze)

Steam distributing coils are a completely different type of coil because they are constructed as a tube within a tube. Every place that you see an outside tube or header, there is an inside tube and header that you can’t see. The steam on the inner tube keeps the condensate in the outer tube from freezing.  The purpose of the Steam Coiloriginal coil design was to distribute the steam evenly along the length of the coil and to eliminate any dead spots on the coil.  A byproduct of this coil was also found.  The coils didn’t freeze nearly as easily as the standard steam coil, so the coils became known as “non-freeze”, which as mentioned, is not completely accurate.  Any coil can freeze under the right conditions, but, this design is what needs to be used when the entering air is under 40F degrees!!! 

Steam Coil Design

Steam coil designs can be very tricky.  Steam coils are totally a function of the system and installation, while other coils operate more independently of the system.  There needs to be correctly designed traps, and they need to be installed in the correct place and depth in the system.  Often, vacuum breakers are also needed in the system.  The piping must also be installed correctly to make sure the steam is entering the coil and not the condensate.  Even with all of those factors, you’ll need a correctly designed steam coil that matches the steam pressure, length of the coil, and the entering air temperature.  Coils can freeze easily.  Coils can be too long in length and the steam cannot travel the length of the coil and distribute evenly.  Condensate can easily be trapped somewhere in the coil, and the result is water hammer. 

Capital Coil & Air has years of experience designing steam coils, and is here to answer any questions and help to design the right coil for your project! 

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Top 5 Reasons Commercial HVAC Coils Prematurely Fail

Capital Coil & Air has come across virtually every scenario over the years in which a commercial HVAC coil had to be prematurely replaced, and we have since created an easy guide targeting the main reasons HVAC Coils prematurely fail.

  • Coil Plugging: If you are not changing filters and/or your commercial HVAC coils are not properly cleaned in a timely manner, your coil will actually begin to act as a filter. When dirt builds up on the coil, that blockage prevents heat transfer and can cause an approximate 20% to 40% drop in performance. Dirt adds to the coil resistance and can be a primary cause for your coil to fail prematurely.
  • Vibration: When your HVAC coils are installed near a moving piece of equipment, vibration can occur and cause leaks. You can tell if vibration is the main cause if leaks are near the tube sheet and look like they are slicing through the tube. If/when that happens, the coils should be isolated from the rest of the system to prevent vibration from causing damage. One way to combat this is by oversizing the tubesheet holes, but many manufacturers will not do this. Condenser Coils are usually the most common victims of vibration.
  • Corrosive Environment: This applies to both the air in the environment and inside the tubes. For instance, if there is a corrosive element in the air, it will eat away at the copper tubes; whether you have 0.020” wall or 0.049” wall. This is very common in coastal areas where there may be salt in the air. To keep the costs down from going to a stainless steel or cupro-nickel coil, we usually suggest coating the HVAC coils. Coatings are almost always within your budget, and its application will only add about a week to the overall lead time. Steam condensate and untreated water can cause corrosion within the tubes of HVAC coils as well. If you have a steam coil that has failed before the one year warranty, there’s a great chance that corrosive agents are in the steam, and it’s eating away at the copper tubes.
  • Freeze-Ups: Most people think that when HVAC coils freeze, the water or condensate laying in the coil freezes into ice and it expands causing the tubes to bulge and eventually spring leaks. What really happens is that the coil will freeze in multiple areas simultaneously, and it’s the pressure between these areas that cause the tubes to swell and eventually burst. These are very easy to spot as the leaks will run the length of the tube rather than around the tube.  ALSO be very careful when considering “freeze-proof” coils!  If you remove 5-6 inches from the fin length to make the “freeze-proof” application fit, your coil’s performance will suffer considerably. 
  • System Design: You would be amazed to learn how many HVAC coils were never designed properly for their systems. If there is a design problem, replacing the coil will only waste time and money; while you have done nothing other than duplicate the previous problem. A little known fact in the replacement market is that a high percentage of all our projects are because the coils were built incorrectly or were never designed correctly in the first place. In some cases, owners attempt to improve the coil’s performance by adding additional rows. Most however do this without taking into account the air pressure drop or fluid pressure drop that comes with it.

When dealing with an HVAC coil manufacturer, try to partner up with one who will walk you through the engineering and explain it along the way. Capital Coil & Air has well over a decade of experience and can help you diagnose whatever problem that you are experiencing correctly the first time. We look forward to working with you on your next project!

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Syracuse University Athletic Dome Renovation

Capital Coil & Air prides itself on its ability handle all jobs – large or small! We quote anywhere from 25-50 projects/day, and there is typically a very diverse mixture of equipment and overall size & scope of projects that need to be engineered and quoted. The majority of our business comes from repeat customers because they know that we treat every job and request with the same importance – regardless of size. Today’s newsletter highlights one of our largest jobs to date to illustrate the fact that Capital Coil has the ability handle any job…no matter the size and scope.

Capital Coil has long understood that your businesses and customers depend on fast responses, fast engineering, fast shipping, and top-quality products. Again, whether it’s (2) small hot water duct-coils that you need overnighted, or banks of chilled water coils, Capital Coil wants you as our customer to be satisfied that you got a “fair-deal” with us on each and every job.

The Syracuse University Dome (SU Dome), in Syracuse, NY underwent an extensive renovation at a cost of $205 million. The old roof was air-inflated/supported and was replaced with an updated design-frame roof. As part of the total renovation, the building also changed out it bathrooms, Wi-Fi, LED lighting, and entire HVAC system. As part of the renovation, Capital Coil was asked to build (64) chilled water coils as a part of the air conditioning renovation project.Capital Coil

Modular Comfort Systems, located in Syracuse, contacted Capital Coil & Air during the planning and budgeting phase of this project. Modular Comfort Systems is a large and highly respected HVAC Representative in central New York State. After purchasing coils from CCA, they re-sold those same coils, as well as other HVAC equipment to the also very highly respected Burns Bros. Mechanical Contractors – also located in Syracuse. Burns Brothers has been working in HVAC, plumbing and process piping for more than 100 years. Both of these companies are the types of companies that Syracuse University would entrust with such an important and high-profile job.

Capital Coil built (64) free-standing chilled water coils in sizes ranging from (33” x 93”) – (33” x 118”). All (64) coils are (8) rows with 304 stainless steel casing, increased tube wall thickness of .035”, with connections built and oriented at 90 degrees to facilitate ease of piping. The coils have all been highly engineered and are exactly correct for this application/project. Each coil weighs over 1,000 lbs, so Capital Coil split up the total order into (2) separate shipments, two weeks apart, in order to help the contractor receive the delivery.

The point of this case-study is to show how proud Capital Coil & Air is to have been tasked with building coils for such a high-profile project. Capital Coil is also proud to have worked with professional organizations like Modular Comfort Systems and Burns Brothers Mechanical. But regardless of the size of the project, you’ll receive the same attention and support as anyone else who reaches out for our assistance. Please contact us as we look forward to working with you on your next project!!

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Fan/Coil Units Without the Mysteries

Lots of companies in the HVAC business attempt to keep their products as complicated as possible in order to lend a certain “mystery” to the industry, which has never made sense to us at Capital Coil. We have all been in this information age for quite some time with more information/data available to more people than ever before. We feel that by removing some of the “secrecies” surrounding fan/coil units, our customers will be able to better understand the products as we do.

Most of our potential customers know Capital Coil strictly for our HVAC coils, which makes sense because the word “coil” is in our company’s name. But some people may not be aware that we do in fact offer multiple fan/coil models with various quick-ship options, or that fan/coils comprise a significant portion of Capital Coil’s overall business.

With that said – what are fan/coil units (FCU’s) exactly?fan/coil units

  • Fan/coils are easy to understand when you remove a lot of the complex terminology. Our definition of a FCU unit is one that is direct drive and not belt driven…easy enough to understand, right? There is a fan, a coil, and sometimes a filter. Capital Coil offers numerous model types, but the only thing that really differentiates the various models from each other is the casing on the outside of the unit. And the casing is typically based on how and where you want to install the unit.
  • The fan is directly mounted on the motor, and the maximum CFM that can be used in these units is typically 1,200 FT/min. However, Capital Coil does offer some units that can have a CFM as high as 3,000 FT/min, or (7.5) tons.
  • FCU’s can be divided into two groups based on airflow – Horizontal and Vertical. Think of fan/coils installed in a hotel or classroom. These are typically vertical units because the air goes from the bottom of the unit to the top discharge airflow.  Horizontal units have horizontal airflow with inlet and discharge both horizontal as well.
  • As mentioned, fan/coil casings are determined based on how and where you want to install the unit. But figuring that out involves asking some additional questions, such as is the unit hidden above the ceiling or is it exposed? Is the unit horizontal or vertical? Does the unit need a filter?
  • Like most any product, there are several “packages” that you can select, such as certain valves, that will make the unit more expensive and complex. But once you strip away the complex terminology and are able to understand the basic design and concept of FCU’s, they are pretty easy to work with.

Now you know that Capital Coil is very much in the fan/coil business, and when you are looking for something fast, Capital Coil should be your first call or email!

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