Tips on Hand Designation & “Counter-flow”

Are your chilled water coils right hand or left hand?  Are you looking into the face of the coil with the air hitting you in the back of the head?  What exactly is counter-flow and why is it important?  Are you completely confused by why right hand vs. left hand even exists?  Most manufacturers probably do not know or understand the technical reasons themselves.

First, let’s figure out what coils even need a hand determination.  Chilled Water Coils, Direct Expansion (Evaporator) Coils, and Condenser Coils are the only coils that need this figured on almost every job.  Hot Water Coils, Booster Coils, and Steam Coils rarely need this determination!  The reason for this is when the coils are only 1 or 2 rows deep, they can be flipped over.  When a chilled water coil is 3+ rows deep, hand determination is much more important because it needs to be counter-flow.  With most suppliers determining hand designation with the air hitting you in the back of the head….do you want the connections on the right or left?

Chilled Water CoilsYou’ve probably heard the term “counter-flow” countless times, but here’s the simplest explanation.  For peak performance, you want the air and the fluid traveling in opposite directions through the coil.  Is it the end of the world if your coils are not counter-flow?  The short answer is no, but you will lose anywhere from 12-15% of the output.  So if your coils are piped incorrectly, don’t expect to get the full performance.  Steam and hot water coils are 1 or 2 rows deep, so again, counter-flow is pretty much irrelevant.  However, it can make a BIG difference with any chilled water or direct expansion coils (3-12) rows deep.

We also get asked many times “what is the proper way to pipe coils?”  Put simply, steam coils should always be fed on the highest connection and the return on the lowest connection.  Water coils should always be fed on the lowest connection and returned on the top connection to ensure that all of the tubes are are fed the same volume of fluid. 

Hand designation and counter-flow are two pretty simple concepts when they are properly explained.  When dealing with a 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 in handling pretty much any scenario that you may come across, so we want to be your coil resource for any and all projects. Please give us a try on your next job!

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Fan/Coil Units Without the Mysteries

Lots of companies in the HVAC business attempt to keep their products as complicated as possible in order to lend a certain “mystery” to the industry, which has never made sense to us at Capital Coil. We have all been in this information age for quite some time with more information/data available to more people than ever before. We feel that by removing some of the “secrecies” surrounding fan/coil units, our customers will be able to better understand the products as we do.

Most of our potential customers know Capital Coil strictly for our HVAC coils, which makes sense because the word “coil” is in our company’s name. But some people may not be aware that we do in fact offer multiple fan/coil models with various quick-ship options, or that fan/coils comprise a significant portion of Capital Coil’s overall business.

With that said – what are fan/coil units (FCU’s) exactly?fan/coil units

  • Fan/coils are easy to understand when you remove a lot of the complex terminology. Our definition of a FCU unit is one that is direct drive and not belt driven…easy enough to understand, right? There is a fan, a coil, and sometimes a filter. Capital Coil offers numerous model types, but the only thing that really differentiates the various models from each other is the casing on the outside of the unit. And the casing is typically based on how and where you want to install the unit.
  • The fan is directly mounted on the motor, and the maximum CFM that can be used in these units is typically 1,200 FT/min. However, Capital Coil does offer some units that can have a CFM as high as 3,000 FT/min, or (7.5) tons.
  • FCU’s can be divided into two groups based on airflow – Horizontal and Vertical. Think of fan/coils installed in a hotel or classroom. These are typically vertical units because the air goes from the bottom of the unit to the top discharge airflow.  Horizontal units have horizontal airflow with inlet and discharge both horizontal as well.
  • As mentioned, fan/coil casings are determined based on how and where you want to install the unit. But figuring that out involves asking some additional questions, such as is the unit hidden above the ceiling or is it exposed? Is the unit horizontal or vertical? Does the unit need a filter?
  • Like most any product, there are several “packages” that you can select, such as certain valves, that will make the unit more expensive and complex. But once you strip away the complex terminology and are able to understand the basic design and concept of FCU’s, they are pretty easy to work with.

Now you know that Capital Coil is very much in the fan/coil business, and when you are looking for something fast, Capital Coil should be your first call or email!

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Cooling Coils & Moisture Carryover

Moisture carryover is present on cooling 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.

  • 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. Cooling Coils

    -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 (Evaporator) Coils 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 of 550 ft/minute, which 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 is here to help you avoid situations like the one described in this post, and we would love for the chance to work with you!

 

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