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.Steam Coil

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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Top 10 Hints for Replacing Tube Bundles in U-Tube Exchangers

There are basically three kinds of shell and tube heat exchangers:

  • “U” Tube heat exchangers where it is possible to remove the entire bundle
  • Fixed tube heat exchangers where the tube sheet are welded to the shell and stationary and the bundle is not removable
  • Floating tube heat exchangers where one tube sheet is fixed and the other floats axially.  This tube bundle is also removable.
  1. The shell for this type of shell & tube exchanger can/will last just about forever. However, the copper tube bundles located inside will often need to be replaced. The idea here is to slide the old bundle out and replace it with a new bundle, using the least amount of labor possible.
  2. One very important question to ask is which types of tube bundles are replaceable? “U” tube bundles and straight tube bundles with “floating tube sheets” can be replaced, while fixed tube sheet bundles must be re-tubed rather than replaced.
  3. Replacing a bundle is pretty straightforward and easy. Simply slide the bundle out and measure the overall length (including the tubesheet). Keep in mind that the bundle’s OAL will always be several inches shorter than the shell’s OAL. Tube Bundles
  4. The next step is to determine the size of the tubes in the bundle. While the vast majority of bundles have ¾” OD tubes, it is possible to have ½” OD, 5/8” OD, or 1” OD.
  5. Next, decide on the tube thickness that you need. Thicker tubes will last longer, but will obviously be more expensive. Typically ¾” tubes will have a .049” wall thickness, but you can easily upgrade if needed.
  6. Including tube supports or baffles, the number of tubes in the bundle should always be the maximum number that you can fit inside the shell. If you are not sure of the # of tubes, contact us, and Capital Coil can tell you the maximum number.
  7. You also want to make sure to count the tube supports or baffles on the length of the shell. While tube supports only serve to keep the bundle together, baffles actually direct the fluid on the shell side to go back & forth across the bundle. If you are unsure which is which, tube supports run the complete circumference of the bundle, while baffles are generally staggered and look to cover only a portion of the tubes.
  8. The only real way to not get the bundle correct is if the tubesheet is not duplicated correctly. First, measure the thickness of the tubesheet. ¾”, 1”, 1 ½” are examples that you’re likely to see.
  9. Next, you want to determine the number of bolt holes, as well as the center to center distance of the bolt holes. Doing this basically determines the bolt hole pattern. The bolts are responsible for connecting the head and the tube bundle to the shell, so they all must match up exactly! But, please also keep in mind that it is possible to have no bolts in the tubesheet as the bolts then bypass around the tubesheet.
  10. Lastly, every bundle has a number of passes that create fluid which runs through the tubes. That fluid will ultimately end up back at the same end. (2) pass, (4) pass, or (6) pass are among the most common. Gasketing and head design determine the number of passes.

 

Replacing a bundle is pretty easy, and it should take you approximately 15 minutes to gather all of the necessary information. But if you happen to run into any difficulties, please call us here at Capital Coil & Air, and we’ll help walk you through everything. We have the capability to build almost any kind of bundle of various construction types and different tube materials. Please give us a try on your next project as we want to be your go-to resource for all bundle replacements.

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Are Your Quick-Ships Shut Down When Needed Most???

Why are quick-ships so important??

Christmas season is in full-swing, and your current coil supplier has suspended all Quick-Ships with little to zero notice to its customers. Does that sound familiar these days? Additionally, the clock is ticking to complete those projects that need to be done by the end of the year. In this industry, this scenario is when “Quick-Ship” availability is an absolute must. Right now, the vast majority of coil manufacturers are scrambling to complete standard orders on regular lead-times, and if by dumb-luck they are able to temporarily offer any type of expedited build, the added premiums are so astronomical that very few customers can afford to use those options.

If you need a new coil, your first inclination will probably be to call the OEM. But more times than not, they are not flexible or nimble enough to handle your emergency within an acceptable time-frame. Quick-ships are generally based on emergency conditions, and that is precisely the worst time to discover that your regular supplier has suspended Quick-Ships.

So why do so many manufacturers seem to get so overwhelmed at various point every year? In short, 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.

Capital Coil’s primary duty as the leading OEM replacement coil manufacturer is to fill in those gaps and work with you to help alleviate any emergencies. Whether you need a coil in (3) weeks, or (5) days, Capital Coil has got you covered.

Capital Coil does not try to be all things to all customers, and we’re most comfortable “staying in our lane”. Our #1 goal is to ensure that we have multiple quick-ship options open all year around…even if that means turning away an order to ensure sure that our Quick-Ships are ALWAYS available!!  Quick-ships

Because Quick-Ships make up such a substantial portion of our overall business, Capital Coil has hit 99.9% of our quick-ship requests over the last (2) years. An unfortunate forklift mistake makes up the other .1%. Throughout the first 6 months of 2022, approximately 80% of all orders were/are quick-ships, and they have either all been completed on time, or are 100% on schedule.

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 will remove many, if not all of the annoying and unannounced shut-downs that come with other manufacturers, so please let us help you when you need it the most!

 

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Light-Duty Commercial Belt Drive Air Handler Units

There are lots of jobs that require large custom built Air Handler Units, as well as jobs that require Central Station Air Handler Units that are semi-custom built units. There are also plenty of jobs that Belt Driverequire neither of the above products. This application only requires that a light-duty standard unit be built that will match the duty and requirements of the job.

 Examples

  • Strip Malls/Shopping Centers
  • Dormitories and other college campus buildings
  • Military installations
  • Office areas in factories or other industrial settings
  • Condominiums

These examples do not need large heavy-duty units that are expensive and custom built. Instead, most of these units require standard light-duty construction that can provide 800-12,000 CFM. These units come with various options and choices, and are well-built with the highest quality components available. However, the units are not designed for overkill.

Capital Coil manufactures “Belt Drive” units that operate from 800 CFM (2 Tons) – 12,000 CFM (30 Tons). They are available in both horizontal and vertical airflow styles. Included are blowers, coils, drives, filters as well as additional accessories if required. Additionally, they are available in Chilled Water Coils, DX Coils, Hot Water Coils, and electric heat if needed.

So, why would you want to use these units in lieu of a heavy-duty air handler? Cost, cost, and cost again are the primary reasons. In addition, the light-duty units weigh less, they are more economical to install, and long-term maintenance is much easier. The overall cost of a Custom-Built Unit or a Semi-Custom Station Unit is dramatically higher and not needed in most installations. Please visit Capital Coil’s Belt Drive Product Page for additional descriptions of our units.

Shipping Schedules

  • Standard lead time: (6) weeks
  • (4) week quick-ship: 30% adder
  • (2) day quick-ship: 40% adder

Capital Coil is 100% transparent on all prices and pricing options. Each option is clearly listed on all quotes to help make your buying experience that much easier.

The Air Handler industry is pretty easy to understand when boiled down. If your job allows you to stay within “Production” type units that are built to normal standards without any customizations, you can save a lot on your price. The proper units for your project are still of the highest-grade quality, but they are much more of a fit for commercial, light-duty jobs.

Capital Coil & Air looks forward to working with you on all of your future Air Handler projects. You’ll be glad you did.

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How Did The HVAC Commercial Coil Replacement Market Originate???

How in the world did the commercial coil replacement market start? This specific newsletter is more of a story than anything technical that we have covered in most of our previous emails or blogs. Rather, this is the story of how one manufacturer’s representative, Robert Jacobs, almost by accident, stumbled upon the concept of the coil replacement market back at a time when the only way one could get a replacement coil was to go through the original equipment manufacturer – (OEM). In full disclosure, Bob Jacobs is the VP of Business Development with Capital Coil & Air.

Way back in the day – (1970’s) – HVAC coils were not stand-alone pieces of equipment as they are considered by some now. Coils were nothing more than a single part in an Air Handling Unit (AHU) or a bank of coils. Like a bearing, a drive, or fan wheel, coils were simply part #’s that one needed to reference with the OEM in order to get a replacement built. This situation was a very good deal for the OEM’s because much like car parts, they could charge upwards of 3x’s the original cost of the coil or “part”. And, it was built according to their schedule/timeline, not yours’.

In the 1970’s, Bob Jacobs was a manufacturer’s rep in the Philadelphia-area, and his main line of equipment was Bohn Aluminum & Brass. Bohn was a division of Gulf & Western and competed against many of the top manufacturers, such as Trane & Carrier. For comparison-sake, Bohn was very similar to what Dunham-Bush is today.Commercial Coil Replacement

During this period, Bob Jacobs was asked by numerous local contractors to replace old and/or broken coils. Due to the lack of a quality alternative, he initially used Bohn for coil replacement projects, but replacing coils was not exactly Bohn’s “sweet spot”. It should be mentioned that during this period, replacement coils were not really on any manufacturer’s radar as a separate product – hence the point of this story. Regardless of the OEM, standard lead-times were upwards of (12) – (14) weeks, and those “replacement parts” were very expensive. It was during this period that he realized that there was serious potential for some kind of HVAC coil replacement market. To test this theory, he initially spent $75.00 on an ad deep within the classified section of “Air Conditioning & Refrigeration News”. It was the old type where one had to “circle the bingo card” to request additional information, and this single ad received over 525 inquiries from across the country!! This eye-opening initial response to his idea made him realize that he had come across something good, but now the challenge was how to satisfy this new market. Bob Jacobs initially contacted Bohn to see if there was any interest in building replacement coils, as well as marketing the idea across the United States. Bohn essentially laughed at the idea and countered that he’d be violating his sales rep agreement by going into the territories of other reps. This was very flawed reasoning as none of the other reps were engineering or selling replacement coils in the first place! Within a week, he had canceled his agreement with Bohn and was looking for alternative vendors. He also decided to run a second ad that received another 450 inquiries; furthering his idea of the need for a coil replacement market.

The next step was to reach out to Singer Coils (yes, like the sewing machine), who was located in North Carolina. Because they had built coils for other manufacturers, he pitched his idea to them along with the request that they build his special or “custom” coils. While initially skeptical of the concept, the doubters were proved wrong as his firm gave Singer over $3,500,000 in business in that first year alone. Admittedly, that $ amount in the first year in a brand new market is impressive whether it’s 1971 or 2021!!

One must also remember that these were the days before fax machines and most certainly before email and the internet. Quote requests for coils were received via USPS and were hand-drawn sketches written on things, such as legal pads, envelopes and pretty much every way imaginable compared with today. Because everything was starting from scratch at this time, there were no coil model libraries or other materials to cross-reference, so going through a random building trying to locate the correct coil to replace could be torturous. However, over the next 6-8 years, his business grew quite rapidly, and he was able to collect and build a substantial reference library of coil drawings and other relevant information. The experiences of the prior 8 years, coupled with his firm’s knowledge of commercial coils, eventually allowed his company to begin building their own replacement coils for the 1st time, rather than relying on a 3rd party manufacturer.

Bob Jacobs’ original coil replacement company developed relationships with literally thousands of customers and laid out the initial blueprint for success in the coil replacement business. Due to that success, you now have approximately (10) alternatives that have attempted to copy his model as it’s become obvious that this is a lucrative market. Even OEM’s have recognized that they need to have a piece of the replacement market. But an important point to remember is that just because a company says or even advertises that they are in the coil replacement business does not mean that they are any good or even fully understand how the replacement market operates. For example, most coil manufacturers today are still more interested in the production of larger quantities, so replacement coils are “special” to them. In other words, sometimes these manufacturers want to be in the coil replacement business, and other times, without telling you, they do not. And not knowing where a company’s focus or priorities lie makes it extremely difficult to work with them under emergency conditions.

Bob Jacobs was there at the beginning and is still quite active within Capital Coil. Having daily access to a resource that literally invented the coil replacement market is what separates Capital Coil from all other competitors. Capital Coil will continue to be your coil replacement experts, and we greatly look forward to the chance to work with you on future projects.

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Need A Replacement Heat Exchanger/Tube Bundle?

To begin with the obvious, shell & tube heat exchangers consist of a tube bundle surrounded and protected by a steel shell. While the shell can seemingly last forever, the tube bundle inside most certainly cannot. The tube bundle is not attached inside the shell, which means that the bundle can be removed if needed to be replaced. In other words, you can simply replace the tube bundle without having to replace the entire heat exchanger. A good comparison can be found with coils inside Air Handling Units (AHU’s). Due to erosion, corrosion or both, coils tend to fail before the entire AHU and subsequently need to be replaced. If everything is done correctly, the new coil should simply “slide” into the place of the old coil. The same is true of tube bundles in that ideally you want to be able to remove the old bundle, and slide in a replacement with little to no extra work. Capital Coil & Air is here to help you throughout the entire process.

Replacement Tube Bundle

The easiest route to ensure that the correct duplicate is built is to first try to cross-reference the model #. While you may not have that information at your fingertips, there is a very good chance that Capital Coil has already built that specific bundle, and/or has the ability to cross-reference whatever model that you are looking to replace. Simply send us a picture of the tag with the model & serial number, and we will do the rest.

Regarding tube bundles, the most common type of replacement bundle can be found in “U” tube type exchangers. These types of bundles are typically water/water or steam/water exchangers.

Steam/Water Bundles

When looking to duplicate a tube bundle, you HAVE to know the bundle’s correct diameter, as well as the diameter of the tubes in order to duplicate the tube area. Additionally, you must duplicate both the tube length and the flange on the bundle to match it up correctly to the shell.

Steam/Water bundles are rather basic in that water is in the tubes, with steam filling up the rest of the shell. Matching performance is almost never the problem, but matching up the dimensions is PARAMOUNT!!  

Water/Water Bundles

Water/water bundles really only differ from steam/water bundles in that there is now water on the shell side as well. Steam automatically fills the shellside, but water does need to be redirected back & forth across the bundle by a series of baffles that operate on GPM & water velocity. The baffles are also an integral part of the bundle, so if duplicated correctly along with the other physical dimensions, performance will not be an issue.  Once again, physical dimensions are PARAMOUNT!

How Can We Go Wrong?

The surest and most common mistake is not correctly matching up the bundle tubesheet to the rest of the exchanger. The tube sheets must fit between the head and the flange on the exchanger, and the bolt-hole pattern must also be an exact match. The bolts are inserted through all three parts simultaneously, and the pattern should match up with all three parts. Sometimes other tube sheets fit between the head and flange, but are also smaller in diameter. The bolts simply bypass the tube sheet and go around it. There needs to be a concerted effort to ensure that the tube sheet dimensions are correct and not too big. Additionally, the gaskets need to be sized and replaced correctly. 

Capital Coil & Air has an established track record of building tube bundles efficiently and quickly. And, in all probability, we already have information on whatever unit you need to get replaced. Like coils, replacing tube bundles usually has a level of emergency attached to it, so we offer multiple quick-ship options if needed. Please give us the opportunity to work with you on your next project, and let us help to take a lot of the guesswork out of your next project.

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