How to make your HVAC OEM Replacement Coil Buying Process Easier??

Roughly 100% of HVAC OEM replacement coil shipments use some kind of trucking company or common carrier. There are occasions when the shipment is small enough to use UPS or FedEx, but the vast majority of HVAC shipments are sent by way of truck. Anyone who has frequently used freight companies has experienced damaged shipments and/or late arrivals. In our industry, these annoyances and inconveniences are typically written off as “the cost of doing business”. Think of the airline industry as an example. Our expectations have been reduced to point where we expect something to go wrong and are pleasantly surprised when the trip is smooth from start to finish.

Many folks might not know this, but even before the pandemic struck, the trucking industry in general had been experiencing a gross shortage of drivers throughout the country. Some estimates have put this shortage of drivers as high as 50,000 throughout the country.

So what does this shortage mean for the HVAC industry? Put simply, it translates into complications and confusion for all involved.

Longer delivery times. For example, a delivery that used to take (3) days is now (5-7).
One major reason for the longer delivery times is that trucks now have many more stops than in years past. There are also many instances of more trips through connecting terminals as well.
More time on the truck usually equates to both “visible” and “hidden” freight damage.
The shipments become harder to track, and with fewer people at the trucking companies doing more work, shipments can and will get lost entirely.

Because the freight process is at the very end of the OEM replacement coil buying cycle, Capital Coil & Air has developed some simple strategies for the entire buying process that should help in avoiding many of the annoyances listed above. We’ve also added a very useful “hint” to counter longer freight delivery times.

Getting a price, delivery & accurate proposal from your vendor: Capital Coil responds to every quote request quicker than any of our competitors, and we are always willing to put that claim to the test. A (2) day delay in receiving your quote is the same as a (2) day freight delay on the back end.
Receiving your submittal drawings in a timely fashion: You need to approve these drawings, so once again, how is a (2) day delay in receiving approval drawings any different than receiving your order (2) days late?
Quick-Ships: As you’ve probably experienced numerous times in the past and/or present, other coil manufacturers seem to be consistently shutting down their quick-ship programs with little to zero notice for the customer. Why is this? Many manufacturers take on a glut of OEM replacement coil 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.

Capital Coil NEVER shuts down our quick-ship programs, and we emphasize NEVER! Over the last (2) years, CCA has hit approximately 99% of all quick-ship orders.

Crating equipment to minimize freight damage.
Shipping on time: Simply put, we consistently ship when we say we’re going to ship.
Select a freight carrier that delivers to your area without interlining or stopping at several terminals: This is when freight damage is most likely to occur!
Pay the carrier fee for a guaranteed delivery date: Although seemingly not well-known, most carriers offer a guaranteed delivery date for a fee of $50-$100. Paying the fee will ensure that your order is now a “priority”, and most freight companies schedule deliveries based on these “priorities” first. If both your order and delivery are critical and time-sensitive, Capital Coil can help you with exploring these delivery options.

Capital Coil & Air will work with you throughout the entire buying and shipping process because you as the customer, deserve to work with a hands on manufacturer that will not turn its back on you once the order has been placed. Please give Capital Coil a try on your next project!

Quick-Ship Fan/Coils & Light Duty Air Handlers

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Steam Distributing Coils (Non-Freeze)

Frozen Steam Coils: How Do You Prevent This?

Commercial Steam Coils: Lengths & Controls

Steam Distributing Coils

How Should Steam Coils Be Designed??

Of all of the various types of coils, steam coils operate in the most complicated ways. They are, in effect, a product of the system and controls around the coil. If not installed correctly, steam coils simply won’t work properly.

Overview:

The object of any steam coil is to have steam enter the coil as steam and exit as condensate. In a perfect scenario, the BTU load on the coil turns steam into condensate just before it’s ready to exit the coil. Under real world conditions however, condensate usually begins to form inside the tubes almost immediately. Especially when dealing with low-pressure systems, you have to find a way to evacuate the condensate from the steam coil.

Coil Pitch:

A good coil manufacturer will internally pitch the steam coil within the coil casing to force the condensate toward the outlet connection. This pitch is usually 1/8 “ per lineal foot of coil.

Coil Length:

If you require steam to travel 144” and make multiple passes through the coil, then, simply put, your system will not work properly. Condensate forms too early, and it cannot escape the coil. Because of this, coils cannot be too long. A better strategy is to break one long coil into two smaller coils side by side, while feeding from both sides.

Tube Diameter:

Steam Distributing coils often have to be 1 1/8 ” diameter tubes. If the BTU load on a coil is really large, then as a result, you will generate many more Lbs./hour of condensate. If the tube diameter is too small, then the condensate, which needs to evacuate, has no place to go.

Traps:

Traps are required on steam coil systems. The traps should be “float & thermostatic” type traps and be located 18 “ below the condensate connection on the steam coil. Without this, the condensate just sits in the system without any place to go.

Vacuum Breakers:

Vacuum Breakers are often installed in coil systems to remove any excess condensate that may remain within the coil.

Insulated Piping:

There is no such thing as a “Condensate” Heating coil, built as a steam coil. IT DOESN’T WORK. However, and this happens an astounding amount of times, due to the long distances the steam has to travel from the boiler to the coil, many times, the steam will enter the coil as condensate due to the piping not being insulated.

Anything that makes condensate lay in a coil is harmful to both the steam coil and the system. You will get a “water hammer” when the system is turned on and the incoming steam just blasts against the condensate. Worse than the loud and annoying sound that produces is the fact that it just destroys the steam coil. The brazing was never designed for “water hammer”. Also, the coils do not heat properly. Have you ever seen a long coil and run your hand down its length only to feel that the entering steam end of the coil is hot but the far end is cold? More times than not, this means that condensate is laying in the coil and not allowing the steam to properly travel the length of the coil.

Steam Coils require a real expertise to design & build. We at Capital Coil have a long history in solving coil problems and building steam coils so that they work correctly the first time. Give us a call for your next job – you’ll be pleasantly surprised!

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Frozen Steam Coils: How Do You Prevent This?

Regardless if you have steam coils or steam distributing (non-freeze) coil, you can freeze ANY coil. When freezes happen, everyone immediately looks to the steam coil as the cause. When in fact, there are numerous reasons that must be looked at well before the coil.

Freezes generally happen in older systems, however if your new system is not maintained properly or correctly installed, your steam coil can and will freeze. For instance, you’d be surprised at how many times dampers are left open, controls fail, freezestats don’t work, etc.

In a Standard Steam or Steam Distributing Coil, a freeze-up can occur when condensate freezes within the tubes of the steam coil. The two most common reasons for freezing steam coils are the steam trap and the vacuum breaker. The function of steam trap is to remove the condensate as soon as it forms. Condensate usually collects in the lowest part of the coil. If your steam trap isn’t installed properly, that condensate will lay in the coil and it will inevitably freeze as soon as it sees outside air. The vacuum breaker also helps clear the condensate, minimizes water hammers, and helps with uneven temperatures. This must be installed on the control valve and always above the steam trap.

Unfortunately, there are no ways to determine exactly where your steam coil will freeze. And a common misnomer is that the condensate turns to ice and the expansion is what causes the tubes of the coil to pop. In reality, it’s the pressure that builds up between freeze points.

Here’s couple tips in your coil design that can help prevent your standard steam and steam distributing coils from freezing:

Standard steam coils should NEVER see any outside air below 40 degrees. If it does, steam distributing is the only way to go!
5/8” OD Steam distributing coils over 72” long are recommended to have a dual supply
1” OD Steam distributing coils over 120” long are recommended to have a dual supply
Make sure your steam coil is pitched if possible. This slopes the condensate to the return connection making it easier to remove the condensate

Give Capital Coil & Air a try on your next project. Our engineering, pricing and service is the best in the industry!

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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.

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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How to Make Sense of Heating Coils

Various winter storms have already ripped through multiple parts of the country necessitating the obvious need for working heating coils!! With conditions such as these, emergencies with your HVAC systems are almost inevitable. THIS is precisely when you need your coil supplier to have the speed and flexibility to be able to tackle whatever emergencies arise.

Of all the types of HVAC coils available, heating coils are probably the easiest to select and understand. Capital Coil has listed the three most common types of heating coils that you are likely to come across.

Hot Water Coils

When looking at a water coil, the first thing to remember is that it is in effect “dumb”. In other words, water coils do not know the temperature of the water moving through it. While standard HVAC water coils are mostly constructed in the same design, the number of rows contained within the coil is a key differentiator in determining if the coil is hot water or chilled water. 99% of all hot water coils are (1) or (2) rows based on performance requirements. The “Delta T” between the entering air temperature and the hot water temperature is very large. As a result, you only need a coil with (1) or (2) rows to do the job. Face velocities across the coil can be anywhere from 600 to 1,200 FPM (feet/minute), while water velocities are usually 2-4 FPS (feet/second). As a result, you will always end up with a (1) or (2) row coil with somewhere between 8-14 fins/inch.

Booster Coils

Hot water booster coils are just another variation of the standard HVAC hot water coil. They are always (1) or (2) rows as well, but the casing is designed for duct work installation. This basically means there is usually a 1” or 1.5” casing on all four sides of the coil. You select the proper size of the coil to make sure the air velocity across the coil is correct and simply transition the duct work to make the casing size around the coil. Generally speaking, the size of the coil face is larger than the duct size, so you must transition the duct to make it larger. Just remember, a booster coil is nothing more than a standard hot water coil that is used for duct work installation.

There can also be a casing variation called “slip & drive”, where the coil is installed in the duct work. The coil does not have the standard casing on all four sides like a flanged coil. Capital Coil’s selection program allows you to pick either option.

Steam Coils

The real secret to any steam coil installation is to know that steam coils are much more of a product of the entire system than any other coil; meaning that other coil types are much more independent of the system. Steam coils require numerous considerations, such as traps, pitched casing, piping flexibility, and vacuum breakers. Steam coils are also built according to steam pressure through the tubes and headers. 2 – 50 psig is considered “low pressure” steam for coils, while 50-100 psig is considered “medium pressure”. Anything over 100 psig is considered “high pressure” steam. An important fact to remember is that each of these categories requires a separate kind of construction with different brazing and different materials. Additionally, almost all steam coils are (1) or (2) rows deep. Steam coils are known either as “standard” steam or “steam distributing”, but the differences are very easy to understand. Outside air temperatures below 40˚F require that you have a “non-freeze” steam distributing coil.

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Why Are Fin Designs On HVAC Replacement Coils Important?

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).

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.
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”)
Each fin has 192 holes stamped in the fin for 5/8” OD tubes (8 Rows x 24 Tubes), and each fin is identical.
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.
Each fin is rippled at the entering and leaving edge of the fin to help create air turbulence.
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 original 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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