Do You Need to worry about performance on replacement HVAC coils?

With replacement HVAC coils, performance is almost never the issue. This is a common mistake that a lot of folks make. When duplicating a coil, your efforts need to be directed towards making sure the coil fits correctly, as that’s usually the main issue. While you may be thinking that doesn’t make a whole lot of sense, here are the main reasons:

  • Coils were never intended to be filters, but that’s exactly what they become over time. For those that routinely work with coils, you know its design is tailor-made for the collection of dirt and Water Coilother air particles The tubes are staggered, which means that dirt can not get through. The fins are rippled and corrugated, which typically leads to the same result. Wet coils tend to collect more dirt than dry coils. The process of cleaning coils is very difficult, and the deeper the coil, the more difficult it is to clean. The end result, depending on the age, maintenance and operation, means that your coils operate anywhere from 50%-70% of their maximum efficiency.
  • Fins do approximately 70% of the work in a coil, with the tubes making up the remaining 30% (generally). When manufactured, the tubes are expanded into the fin collars. But, over time, the fins tend to loosen a little. While not sliding back and forth, the fins lose efficiency and their performance is lessened.
  • So what’s your typical solution after 5, 10 or 15 years? You’d probably raise or lower the water temp on you coil. You might also speed up the drive to get more CFM across the coil. You’ll try most anything to make up for the loss of the coil’s efficiency. Everybody does.
 

But when you replace the coil, it’s new and clean. Additionally, with a new fin/tube bond, your new coil is operating at 100% efficiency, while the old coil was working at 60% – 70% efficiency…maybe. With this automatic increase in efficiency means that performance is not really the issue. Your main concern should be that the coil fits in the space available. Otherwise, your new coil is nothing more than an ugly, metallic coffee table.

Your main goal is to replace your coils with as little trouble and cost as possible. While you may still have offsets in piping, as well as other small installation adjustments, performance should be the least of your worries. We’re here to help you meet your requirements quickly and easily.  CALL OR E-MAIL US!  We look forward to the opportunity to work with you on your future projects.

 
Replacement HVAC Coils

RELATED POSTS

Construction Vs Performance: Need To Know Terminology

Tips on Hand Designation & Counter-flow

Four Things That You Need When Buying Replacement Coils


Condenser Coils Failing? Here’s probably why….

Did you recently turn on your DX systems only to find your Condenser Coils are not working?  Simple fix right?  Unfortunately, no.  If you get lucky, you can send us the model number of the unit, and there’s a great chance we’ve already built it.  In the case that we do not have that model number on file, you have two options.  You can go back to Carrier and wait two months for an OEM part while paying through the roof.  Or you call Capital Coil, and we’ll walk you through the engineering it takes to replace a condenser coil.                                                                      Condenser Coil

Very rarely do condenser coils ever freeze so the first thing you’re going to want to know is if your coil died of corrosion, old age, or possibly vibration.  Old age is obviously preferable because with a few easy dimensions, we’ll have enough to price up your duplicate coil.  Condenser coils are usually outside and are easily accessible for measurements and digital pictures.  With just the size, the rows, and fins/inch, you can get a price.  And digital pictures of the headers and return bends will give us a good idea of the circuiting and sub-cooler circuits. 

If the coil has been eaten away by corrosion, it was an improper design to begin with.  Most people don’t know that salt in the air will ruin aluminum fins within a year or two.  There are two ways to combat this.  The first option is to make the switch to copper fins and stainless steel casings.  While this will extend the life of your coil considerably, most people are not too happy about the additional cost over aluminum fins.  The second option is to use a coating.  Coatings are the much more popular choice.  They are a fraction of the cost as copper fins and only add one week to your lead time. 

When your HVAC coils are installed near a moving piece of equipment, vibration can occur and cause leaks.  The area where these leaks occur is very important and will clue you in to if the problem is vibration.  If they are near the tube sheet and look like they are slicing through the tube, 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.

The last concern is with cleaning condenser coils.  Since condenser coils see outside air almost exclusively, they need to be cleaned more than other coils.  The reason for this is most condenser coils have fin spacing of 12-20 fins/inch.  With fins that tight together, the coil can and will act like a filter.  And when the coil is clogged up, the performance suffers greatly.  Recently, we’ve been getting more and more calls about using a heavier fin thickness.  This is to help with high pressure cleaning and corrosive cleaning agents. 

When dealing with an HVAC coil manufacturer, 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 has seen every issue to make sure your everything from the quote to the installation go smoothly! Give us a try on your next project!

RELATED POSTS

Top 5 Reasons HVAC Coils Prematurely Fail

You should never have to worry about performance on replacement coils. Well… almost never!

Repair or Replacement HVAC Coils?


Direct Expansion & Chilled Water Cabinet Coils

There are lots of ducted cooling applications with chilled water and/or DX (Evaporator) coils where you need to add incremental cooling to an existing system. However, there is an important difference when using heating coils. Because it’s a Cabinet Coilheating coil, there is no humidification occurring or water/condensate to draw. Due to these factors, cooling coils require a little more creativity and labor to install.

At Capital Coil & Air, we have removed all of the guesswork out of the application. Capital Coil manufactures Custom Coil Cabinet sections from as small as 12” x 12” sections to as large as 54” x 90” sections. We manufacture these units in both Chilled Water and DX (Expansion), as well as in 1/2” & 5/8” copper tube coils. You have the option to select anything from (3) rows to (8) rows. Additionally, we will custom-design the Cabinet around whichever site you select. Cabinet units include both insulation & drain pans, while the supports and casing allow you to connect directly to the ductwork. We can also add a Heating Coil inside the unit for more dehumidification if needed. Cabinet Coils are perfect for either heavy or light-duty installations.

All Cabinet Coils are available on Capital Coil’s Quick-Ship Program as well. As you are probably all-too-familiar, trying to custom design coils in the field is a pain. Using Cabinet Coils will greatly ease the whole installation process. Please see our Insulated Cabinet Coil Brochure for more details on available custom sizes.

Capital Coil & Air looks forward to the chance to your coil replacement specialists. Please give us a try on your next project!

RELATED POSTS

Chilled Water Coils & Moisture Carryover

New Product Offering: Insulated Cabinet Coils

Top 10 Chilled Water Coil Facts


Chilled Water Coil Circuiting Made Easy

Chilled Water Coil

Circuiting a chilled water coil is one of life’s great challenges in the coil business. You’re bound to run across folks with years of experience in the industry that can not effectively explain this concept. While not the most exciting of subjects, the necessity of circuiting chilled water coils can not be overstated. Capital Coil & Air has attempted to simplify the idea of circuiting as much as possible.

For starters, circuiting a chilled water coil is ultimately up to the performance of that coil. Circuiting is really a balancing act of tube velocity and pressure drop. In other words, think of a coil as a matrix. Each coil has a specific number of rows, and a specific number of tubes within each row. For example, a chilled water coil might be 36 inch fin height and 8 rows deep. The coil has 24 tubes in each row, and multiplied by 8 rows, there is a total of 192 tubes within the coil. While you can try to feed any number of tubes, there are only a few combinations that will work.

    • Feeding 1 tube – you will be making 192 passes through the coil, which will essentially require a pump the size of your car to make that process work.

 

    • Feeding 2 tubes – equates to 96 passes, and your pressure drop will still be enormous.

 

    • Feeding 3 tubes – 64 passes, which is still too many.

 

    • Feeding 4 tubes – See above.

 

    • Feeding 5 tubes – Impossible as 5 does not divide evenly into 192 (passes).

 

    • Feeding 6 tubes – Still constitutes far too many passes, which again leads to additional pressure drop.

 

    • Feeding 7 tubes – Same rule for feeding 5 tubes.

 

    • Feeding 8 tubes –  Same rule for feeding 6 tubes.

 

    • Feeding 24 tubes – This feed consists of 8 passes, which is in the ballpark, and with a pressure drop you can live with.

 

    • Feeding 32 tubes – 32 tubes will see 6 passes. You might see a slight decrease in performance, but it’s off-set by a continuously better pressure drop.

 

  • Feeding 48 tubes – The magic combination, as 4 passes typically elicits the best performance and pressure drop simultaneously.

Rule #1: The number of tubes that you feed must divide evenly into the number of tubes in the chilled water coil.

Rule #2: The chilled water coil must give you an even number of passes so that the connections end up on the same end.

Rule #3: Based on the number of passes, you must be able to live with the resulting pressure drop. Acceptable tube velocity with water is between 2 and 6 ft. per second.

You’re bound to run into different terminologies depending on the manufacturer. More times than not, the different verbiage confuses more than it clarifies. However, understanding the basic tenets of chilled water coil circuiting will remove much of the perceived difficulty.  Check out Capital Coil’s Chilled Water Coils product page.

 

Related Posts

Coils and Counter-flow: 5 Common Questions

Chilled Water Coils & Moisture Carryover

Top 10 Things You Need to Know About Chilled Water Coils


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?

Counter-Flow

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.

 

RELATED POSTS

Tips on Hand Designation & Counterflow

Chilled Water Coils & Moisture Carryover

Chilled Water Coil Circuiting Made Easy


10 Things To Know About Chilled Water Coils

Chilled Water Coil

1. A water coil is a water coil. There is really no difference between hot water coils and a chilled water coils in construction. Hot water coils are usually 1 or 2 rows and chilled water coils are usually 3 to 12 rows deep.

2. The vast majority of chilled water coils are constructed from either 1/2″ OD tubes or 5/8″ OD tubes. A lot of that depends on the tooling of the original equipment manufacturer and what is more economical. Either size can be used and substituted for each other, which makes replacing your coil that much easier.

3. 1/2″ Tubes are on 1.25″ center to center distance. 5/8″ tubes are on 1.5″ center to center distance. For example, if a chilled water coil has a 30″ fin height, there will be (24) 1/2″ tubes per row or (20) 5/8″ tubes per row. The tube area of the coil is remarkably the same. They are almost interchangeable.

4. The quality of the coil often times is directly tied to the tube thickness. Many installations have water not treated properly or tube velocities that are too high. There are few perfect installations in real life. Increasing the tube wall thickness on a chilled water coil is a great way to ensure longer life.

5. Fins make great filters! Of course, they are not designed to be filters, but it happens. You can make any coil cheaper by making them 14 fins/inch with less rows rather than 8 or 10 fins/inch. Just remember that deep coils are very difficult to clean. Cheap is not the way to go most of the time!

6. Fins are designed for maximum heat transfer. They are much more complicated in design than they appear to be when looking at the chilled water coil. They are rippled on the edge to break up the air. They are corrugated throughout the depth of the fin. The tubes are staggered from row to row and the fin collars are extended. All of this to maximize heat transfer. Unfortunately, the byproduct of this is the fins can end up being great filters. Be careful in the design of any chilled water coil.

7. Fins are aluminum for a reason! They give you great heat transfer at an economical cost. You need a compelling reason to switch to copper fins as copper is very expensive, and you’re likely to double (or maybe triple) the cost of the coil. Coatings are popular for this very reason.

8. Many chilled water coils are built with 304 stainless steel casings. The casings are stronger, they last longer, they are stackable, and it’s fairly inexpensive. After all, what is the point of building the best coil possible and have the casing disintegrate over time around the coil? Sometimes, it’s money well spent!

9. Circuiting the coil is the tricky part of any coil. Circuiting is nothing more than the number of tubes that you want to feed from a header. There are two rules. You must keep the water velocity over 1 foot/second and below 6 feet/second. 3-4 feet/second is optimum. The second is the number of tubes that you feed must divide evenly into the number of tubes in the coil.

10. Replacing  your chilled water coil is easy. Rarely do you have to worry about the performance. When you replace a 20 year old coil, it is dirty and the fin/tube bond is not good. The coil is probably operating at 1/2 of its capacity at best. When you put a new coil on the job, your performance will automatically be terrific. Your main concern is now making the sure the coil physically fits in the space allowed. And always have this in the back of your mind: Smaller is always better than too large. Smaller you can always work with, whereas too large makes for a very ugly and expensive coffee table.

There you have it – everything you need to know about chilled water coils. Interested in learning more, please reach out to Capital Coil & Air! We look forward to the opportunity to be your coil replacement specialists!

RELATED POSTS

DX & Chilled Water Cabinet Coils

Coils and Counter-flow: 5 Common Questions

Top 5 Reasons HVAC Coils Prematurely Fail


The Smart Approach to Buying HVAC Coils (and Saving Money)

HVAC coil replacement does not have to be cost prohibitive. As you are all aware, money is tight these days, and budgets for maintenance and upkeep are constantly being cut. People are asked to do more with less, so every dollar spent must be spent wisely. In our previous newsletters, we have outlined various reasons about why you should do business with Capital Coil & Air. However, one of the most compelling reasons is cost and how you spend your money.

We now live in an age where you can skip “middle men” and buy direct from a manufacturer or supplier. Think about your own life and how your own personal shopping habits have changed over the years. When was the last time you used a travel agent to book a trip? In 2020, you’re much more likely to go to Tripadvisor or an airline’s website and make travel reservations yourself. Greater access to more choices gives you the opportunity to save money in the process.

Spending money in business these days is no different. Consumers have access to more information than ever before. Consumer studies show buyers get 60% of their product information from a firm’s website before ever speaking with a sales rep. The days of an account manager or manufacturer’s representative being the sole source of information are over. Right now, you can access Capital Coil’s website and see our entire HVAC product offering, including dimensions, quick-ship programs, and our Coil Selection Program. With information at the press of a button, Capital Coil’s expert customer service will consult with you to ensure that you’re getting exactly what you need, when you need it. Working with Capital Coil & Air directly cuts out that “middle man’s” costly mark-up and saves you money without sacrificing quality. Avoiding the “middle man” and having a direct line to the manufacturer also ensures quick response times, and helps to make sure that no information gets lost in translation.

Capital Coil & Air does have a select number of exceptional representatives in a few areas, and because they are valuable assets in the HVAC industry, we are comfortable passing your project information along to those representatives. But if not in one of those areas, you are free to work with us directly.

At the end of the day, technology has allowed you as the consumer to buy smarter, faster, and cheaper. Aside from those previously mentioned “middle men” who does not want faster and cheaper? Capital Coil & Air would like the opportunity to be your “direct supplier” on present and future projects. Give us a call and test us out!

 

RELATED POSTS

Top 10 Questions You SHOULD Be Asking Your Coil Supplier

Four Things That You Need When Buying Replacement Coils

Your Goals as a Buyer of Commercial HVAC Replacement Coils


Repair or Replacement HVAC Coils?

Regarding replacement hvac coils, there are multiple reasons why coils can fail prematurely. Sometimes, they 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 on-going maintenance, air quality, and water/steam quality all have an effect on a coil’s lifespan.

Chilled Water 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.

 

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.

RELATED POSTS

Four Things That You Need When Buying Replacement Coils

Replacement HVAC Coils: 10 Common Ordering Mistakes

Top 5 Reasons HVAC Coils Prematurely Fail


Coil Costs: What Will Make Your HVAC Coils More Expensive?

We get questions all the time about how we build our HVAC coils, and what will add costs and what will not. This post will address the many inaccuracies other “mass production” manufacturers Hot Water Coilshave put out there. It’s very simple. There are only three areas on a coil that will add costs: the casing, the tubing, and the fins. Now we’ll deal with the many inaccuracies that most manufacturers try and “upsell” to you.

  • Connection sizes: There should be no additional cost switching from a 2” MPT connection to a 3” MPT connection. Only on rare cases with a 4” or 5” connection, should you ever see an adder in price.
  • Pitching the casing in a steam coil: All steam coils should be pitched. There is not some mysterious adder you need to pay to have you coil built the right way.
  • Casing depth and dimensions: Whether you want your coil 4” deep or 8“ deep, or want a 2” flange instead of a 1” flange, there should be no cost associated with simply more sheet metal.
  • Distributors on a DX Coil. This is our favorite. We actually had a call from a contractor who asked how much extra it was to get a distributor on his DX Coil. Distributors come standard with DX coils!
  • Flanges for “stackable” coils. This is just standard practice to meet the needs of your customer.

Coil Casing Adders: Most HVAC coils we manufacture are built with 16 ga. galvanized steel casing. We offer 3 other options that are slightly more expensive, but it all depends on your application if any of them are actually needed. Stainless steel casings are used in a corrosive atmosphere and are the most expensive option (even then, it’s only 10-15% more). 14 ga. galvanized steel casings are used primarily in coil banks where you might have between 2-4 coils stacked on one another. This adder for 14 ga. casing is only roughly 2-3% per coil.

Tubing Adders: There are many materials options in tubing and we offer all of them. Whether you need stainless steel, carbon steel, cupro-nickel, or standard copper tubes, we can build exactly what you need. Like any product, the more unusual the material, the more expensive the cost is. For most jobs with just copper tubes, adding a thicker tube wall will add only 10-15% in cost to the job and could double the life of your coil. For just a couple hundred dollars, that coil that would last 10 years could last 20. Some applications, like high pressure steam coils, require a thicker tube wall or more durable material or the life span of that coil will be extremely short. You’d be surprised at how many other manufacturers’ coils we’re asked to rebuild with the correct materials.

Fin Adders: Most coils are offered with aluminum fins with a thickness of .006”. The adders to go up in fin thickness are not much, but always remember, the thicker the fin, the more air pressure drop it’s going to add to your coil. The most costly adder you can do to a coil is adding copper fins. It will double the cost of your coil, and in some cases, be 2.5 to 3 times more expensive. This wasn’t the case 20 years ago, but the price of copper has risen over the last few years. We usually recommend coating your coils instead. It’s far more economical and only adds a week to the lead time.

Capital Coil & Air understands that people do business with you like and who you trust. Coil manufacturers should be an open book with this information. Unfortunately, most try and prey on what you don’t know. Hopefully, this helps with any confusion. Capital Coil & Air looks forward to working with you!

RELATED POSTS

Four Things That You Need When Buying Replacement Coils

10 Things You Need to Know to Buy Replacement Coils Effectively

The Smart Approach to Buying HVAC Coils (and Saving Money)


Chilled Water, DX (Expansion) Coils & Moisture Carryover

Moisture carryover is present on DX or Chilled Water coils where dehumidification happens.  Many people do not think it’s a problem…until you have moisture running down ductwork or spewing all over the inside of an air handler. If you’ve ever experienced that then you probably know all of these rules regarding moisture carryover.Chilled Water Coils

  • Entering air temperatures of 80/67 of return air in the Northeast carry far less moisture than an outside 95/78 entering air temperature in Florida. Outside air always has more moisture. Your location plays a part as well. The drain pans will absolutely have be sized differently. Florida’s will be much larger in size.
  • Fin design is irrelevant when it comes to moisture carryover. Whether you have copper corrugated fins, or aluminum flat fins, plate fins or even the old fashioned spiral fins, none of it has any effect on moisture carryover.
  • Lastly, be careful when installing a new chilled water or DX coil in a system. Many end users like to increase the airflow on older coils because those old coils can act like filters, the fins are covered in dirt/dust and you’re not getting the same airflow through the coil. This dirt on the coil also semi-prevents moisture carryover. When that brand new chilled water coil is installed, the airflow might be higher than that 550 ft/minute and that, of course, will cause moisture carryover problems. 

 

Please give us a call with any questions about your coil, your system or its design. Capital Coil’s engineering is unparalleled in the industry!

RELATED POSTS

10 Things You Need to Know About Chilled Water Coils

Top 10 Chilled Water Coil Facts

Chilled Water Coil Circuiting Made Easy