IN NEED OF A COIL YESTERDAY??

Why are quick-ships so important??

With winter and various “polar-vortex’s” in full swing, time is not on your side if your current supplier isn’t able to meet your needs. Generally speaking, most jobs require some form of “quick-ship“.

Approximately 70% of all Capital Coil’s orders over the last (3) months have involved some sort of quick-ship. Quick-ships are an integral part of Capital Coil’s overall business structure, and for that specific reason, unlike other manufacturers, Capital Coil & Air NEVER shuts down its quick-ships!!! Steam Coil

You can call the OEM, but more times than not, they are not flexible or nimble enough to handle your emergency within an acceptable time-frame. Whether you need a coil in (3) weeks, or (5) days, Capital Coil has got you covered.

Quick-ships are generally based on emergency conditions, and that is precisely the worst time to discover that your regular supplier has suspended their quick-ships. When we call Capital Coil reliable and dependable, one of the main reasons is because of our ability to keep our quick-ship program open 12 months/year.

Capital Coil does not try to be all things to all customers, but quick-ships are an integral part of our business. Keeping our quick-ship program available all year is a top priority, and this has allowed us to hit 99.9% of our quick-ship requests over the last (3) years. An unfortunate forklift mistake makes up the other .1%. Through the last 3 months of 2019, approximately 75% of all orders were quick-ships, and they have either all been completed on time, or are 100% on schedule.

So why do so many manufacturers seem to get so overwhelmed at some point every year? Many manufacturers take on a glut of OEM business, or other large projects with small profit margins. In many cases they do this simply to keep the factory running during the slower periods of the year. This has the effect of delaying standard lead times, and in many cases, cancelling quick-ships altogether. It is very hard to do business with companies that make themselves unavailable when you need them the most.

An RFQ that sits on a desk unanswered is useless to everyone involved. If you need a quote, you’ll have your price and any required submittals that same day. It really is that simple and easy! Working with Capital Coil removes many of the annoying and unannounced shut-downs that come with other manufacturers, so please let us help you when you need it the most!

 

RELATED POSTS

Uncertain About Recent Changes In The HVAC Industry?

Repair or Replace Your HVAC Coils?

10 Things You Need to Know to Buy Replacement Coils Effectively

 


Construction Vs Performance: Need To Know Terminology

If you have ever dealt with commercial HVAC coils, you have probably come across numerous “industry terms” with little to no explanation as to what these terms actually mean. To further confuse you, some verbiage is specific to the actual construction of the coil, while others are only important when determining a coil’s performance. If you do not work with coils on a frequent basis, it is hard to decipher what exactly these terms are referring to. To help translate this industry verbiage, Capital Coil & Air has come up with a list/glossary of the most common and relevant terms that you are likely to come across on most coil jobs.

 Performance

  • AHRI (Air-Conditioning, Heating, and Refrigeration Institute): Developed industry standards for air conditioning, heating, and commercial refrigeration equipment. All of CCA’s coils are AHRI-certified, so you know you’re getting dependable quality and performance in every product.
  • Air Pressure Drop: Air Pressure Drop is a result of Flow Rate, Fin Type, Rows and Fins per Inch. In addition, on either Chilled Water or DX (Evaporator) Coils, the air pressure drop is affected by the condensate on the fin surface.
  • Airflow (CFM): Cubic Feet per Minute, which refers to the amount of air flowing across the coil. A typical cooling coil should produce between 400-500 FPM. You want to avoid exceeding 550 FPM on all Chilled Water & DX Coils. Too little airflow means your coil is not running at peak capacity, while too much airflow can result in excess water carryover.
  • Entering Air Dry Bulb Temperature: You guessed it! The sensible temperature of the air entering the coil.
  • Leaving Air Dry Bulb Temperature: The sensible temperature of the air leaving the coil. Why does this matter? If you are trying to replace and duplicate a coil’s performance, making sure that your new coil can meet or exceed the old coil’s leaving air temperature is a crucial factor.
  • Entering Air Wet Bulb Temperature: This temperature signifies the amount of moisture in the air entering the coil.
  • Leaving Air Wet Bulb Temperature: Conversely, this temperature refers to the amount of moisture in the air exiting the coil.
  • Total Capacity: The sum total of a coil’s sensible and latent capacities.
  • Steam Pressure: Only relevant to steam coils, the saturated steam pressure at the inlet of a steam coil. Steam pressure is usually relative to the steam coil’s total capacity.
  • Steam Condensate: Again, applies only to steam coils and is a measure of the condensate generated by that steam coil.

Construction

  • Casing Type: The supporting metal structure for tubes and the header. Different casing options include Flanged (standard), Slip & Drive, Inverted, Stackable, and Collared End Plates & End Plates only. Steam Coils require Pitched Casing to allow for adequate condensation drainage.
  • Casing Material: The coil’s casing can be made from a variety of different materials. Options include: 14 or 16 Gauge, Galvanized Steel; 304 or 316 Stainless Steel; Copper & Aluminum. Please contact us directly to see about options other than those listed.
  • Connection Material And Type: Standard connection types are MPT (Male Pipe Thread, threaded on the outside), FPT (Female Pipe Thread, threaded on the inside), ODS (Sweat Connections, no threads)
    • Water & Steam Coils: Copper MPT, FPT, (with options for steel MPT & FPT)
    • DX & Condenser Coils: Copper ODS normally
  • Circuiting/FeedsCircuiting is determined by the number of tubes in each row divided by the total number of tubes fed (or feeds). Feeds are also known as the number of parallel circuits in the coils. Always feel free to call Capital Coil’s sales department with any circuiting-related questions.
    • Water Coil: Enter the coil’s performance data into CCA’s coil selection program, and select the “auto” sizing option to determine the optimal number of feeds.
    • Condenser Coil: Since the condenser is a rating program only, the user must enter a value for the number of feeds. A good rule of thumb is to have approximately 8 – 15 psi refrigerant pressure drop in the condenser.
    • DX Coil: Enter coil’s performance data into CCA’s coil selection program, and select the “auto” sizing option to determine the optimal number of feeds.
    • Steam: Always a full or double circuit
  • Fin Height: FH is measured in the direction of the fins, or perpendicular to the direction of the tubes.Water Coil
    • For 5/8″ tube coils, fin heights are available in increments of 1.5”
    • For 1/2″ tube coils, fin heights are available in increments of 1.25”
    • For 3/8″ tube coils fins are available in 1.00″ increments
  • Fin Length: FL is always measured in the direction of the tubes, regardless of which direction the tubes are running.
  • Fins per Inch: Represents the fin spacing on the coil. The number of fins per inch is an essential component when ordering a replacement. Using a standard ruler, simply count the number of fins per inch on the coil.
  • Number of Rows: Rows represent the coil depth and are always counted in the direction of the air flow, regardless of how the coil is mounted. Count the number of rows by viewing the header end or the return bend end of the coil.
  • Hand (Left or Right): A coil’s hand is determined by the direction of the airflow. Look at the finned area of the coil, and if the air is hitting you in the back of the head, look to see which side of the coil the headers are located. If the header(s) are located on the right side, then the coil is right-handed. Likewise, if the header(s) is located on the left side, it is left-handed. An important point to remember is that you always want the airflow to run counter to fluids, refrigerant and steam flow.

Miscellaneous

  • Laminar Flow: Tends to occur at lower fluid velocities, below a threshold at which it becomes turbulent. In other words, laminar flow is smooth while turbulent flow is rough. Greater heat transfer occurs in a coil with turbulent flow as opposed to a calm, laminar flow.
  • Dry Weight: The estimated weight of the coil; not counting internal fluids or packaging.

RELATED POSTS

Tips on Hand Designation & Counter-flow

Coils and Counter-flow: 5 Common Questions

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


Why Is Fin Design On HVAC Coils Important?

HVAC Coils

At first glance, fin designs on HVAC coils seem about as exciting as watching grass grow. “Why would I ever care about fin design 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 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.

RELATED POSTS

Repair or Replacement Coils?

Top 5 Reasons HVAC Coils Prematurely Fail

Are You Asking Your Coil Supplier These Questions?


Top 10 Chilled Water Coil Facts

Every Chilled Water Coil selection is about balance. Your coil selection balances the rows/fins versus the cost of the coil pressure drops/performance. Trying to cut corners on your initial selection may save you money upfront, but you will inevitably pay it back down the line through added energy costs. This is a truism for every manufactured coil.

  1. Fins cost less money than rows/tubes. A good cost-cutting tool when selecting a coil is to choose 14 fins/inch. This will turn your (8) row coil into a (6) row coil, which will dramatically lower your costs. If you choose to go this route, one thing to keep in mind is that 14 fins/inch will be semi-inconvenient to any maintenance crew tasked with cleaning the coil. Don’t expect a Christmas card from them that year.
  2. That raises the question of whether or not you can even clean a deep (6) or (8) row coil? In short, you can, but it is not easy. Chilled water coils are especially difficult to clean because they are almost always wet. Due to this fact, they typically attract dirt and additional particles that other coils do not. Generally, when cleaning a coil, most of the dirt get pushed to the middle, and for that reason, 14 fins/inch may not be the best idea after all. Chilled Water Coils
  3. Did you know that fins do approximately 70% of the heat transfer in a chilled water coil, while the tubes are only responsible for the remaining 30%? This is precisely why the fin/tube bond is so important. Without a perfectly crafted fin/tube bond, coils become inefficient very quickly. You pay for that inefficiency through increased energy costs.
  4. How long does a coil last? At what age can I expect my coil to fail? Unfortunately, there is no single answer to either question. Everything is dependent on a combination of maintenance, duty, and numerous other factors. If your initial selection was correctly chosen, and proper maintenance was kept, 15-20 years is a good timeframe.
  5. You may have a situation where your coil is 20 years old, and everything appears to be operating in good condition. There are no leaks and all looks ok. However, over that length of time, what you don’t see is that the fins have thinned and are no longer bonded to the tubes, and the coil is dirty in places that you cannot see. Again, while the coil may look to be running in top form, it’s probably only running at 60% capacity. Most likely, the tubes have also thinned over time, so when the next deep freeze occurs, you can guess the likely outcome.
  6. You really need to replace the coil, but have been told to make do with the current coil? To make up for the lack of efficiency, you might try to “jury-rig” your system. One method is to change the drive on the fans to deliver more CFM. This increases the air pressure drop, which in turn increases motor brake horsepower. Another option to help increase the coil’s efficiency is to lower the temperature of the chilled water from the chiller. We tend to mess with the system and apply temporary Band-Aids, when replacing the coil is the only guaranteed long-term solution.
  7. If you want to spend money wisely on a chilled water coil, simply make the tubes thicker. The tube thickness for a 5/8” tube coil is .020” thick, so increase the tube thickness to .025”. The same applies for a ½” tube coil, with a tube thickness of .016”. Increase it to .020”. By doing this, you get the added bonus of making your return bends thicker, which also helps to extend the life of the coil.
  8. Not quite sure about circuiting on a chilled water coil? You are going to have a hard time making an accurate selection unless you understand how to circuit a coil. Circuiting is really nothing more than selecting the number of tubes that you want to feed, and how many passes the water makes through the coil – depending on your GPM. Circuiting is one of the most important factors in ensuring that your coil is running at peak-performance.
  9. Curious about the balance between cost, size, materials, and maintenance? Every chilled water coil needs to be maintained for its entire life-span. If you’ve made your selection, and something seems off about the coils, chances are mistakes were made during the selection process. Some indicators include the coil being too big for the space allowed, or incurring out of control energy costs. What is the point of saving $500 on a chilled water coil if you have to spend $5,000 in maintenance over its life-span?

As coil replacement experts, we run into this issue every day. Our goal is to work with you to ensure your selections are correct the first time. The person in charge of budgets will be grateful to you over time. Capital Coil & Air welcomes the opportunity to work with you on your next coil project! We want to be your coil replacement specialists.

 RELATED POSTS

Chilled Water Coil Circuiting Made Easy

Chilled Water Coils & Moisture Carryover

Top 10 Things You Need to Know About Chilled Water Coils