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!

 

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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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How to Make Sense of Heating Coils?

Various winter storms have already ripped through multiple parts of the country, and we’re not even into 2020 yet!!  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.

 

Capital Coil’s available shipping schedules: 

 

 

Hot Water, Any Size, Replacement or New:

3-4 weeks: Standard shipping

10 work days:  Add 20% premium

5 work days:  Add 40% premium

3 work days:  Add 75% premium

Hot Water Booster Coils

Any size, any rows, any fins, any quantity:  1 work day to 2 weeks

Steam Coils (Standard or Steam Distributing)

3-4 weeks:  Standard shipping

10 work days:  Add 20% premium

5 work days:  Add 40% premium

3 work days:  Add 75% premium

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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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