Coils – Construction vs. Performance (Credit to Guest Blogger: Matt Jacobs, Capital Coil & Air)
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 exactly what 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.
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.
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/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)
SMARDT, Danfoss Turbocor & Southern Air Win Association of Energy Engineers Award for Citizens Bank Installation
The New England Chapter of the Association of Energy Engineers (AEE) recently announced its 2007 Energy Awards Projects. Among the award winners were Southern Air and Citizens Bank for the Citizens Bank data center project in Medford, Massachusetts.
The project achieved multiple goals including:
1) An enticing electric utility rate being available if the data center could be switched over to in-house emergency generator power controlled by the utility company during peak demand periods.
2) The customer wanted to be able to lower condenser water temperatures under light load conditions, to significantly reduce energy consumption.
3) By reducing overall energy consumption, the owner would realize financial benefits of utility rebates and reduced electric power costs, and thereby offset the project cost.
Superior Energy Savings
Reduced Operating Costs
Reduced Environmental Impact
Built In Redundancy
Total Cost of Ownership
The facility’s existing chillers were replaced with two 90 ton SMARDT brand chillers that utilize Turbocor oil-free, variable speed, centrifugal compressors. Because Turbocor compressors draw less than 2 amps at startup (rather than a typical in-rush current of 300-400 amps), they are very compatible with the emergency generator application. No in-rush current greatly reduced the generator capacity that would otherwise be needed. Furthermore, the oil-free compressor design enhances operation at the lower condensing pressures that can be achieved as oil return is no longer an issue. This provides extremely efficient operation at low load conditions, where the chillers will operate most of the time.
Featured Manufacturers: SMARDT specializing in using Turbocor compressors in its full line of water and air cooled chillers for commercial and industrial applications.
We’re Different: Your DAC Sales Engineer designs your system, executes the CAD work, coordinates the bidding process, and takes personal responsibility for your job from start to finish. No other firm offers this level of continuity, and it gives our customers a lot more confidence. No matter where you are in the process, we don’t shuttle you between departments. We don’t miss calls or information or opportunities. Our whole team is behind you, but your DAC Sales Engineer is always right beside you.
We believe in a better process: At DAC Sales, the process is as important as the finished product. Our nationally recognized design team believes every HVAC system design should be a custom HVAC system design. We make your system a perfect fit for your building, your budget and your priorities. When you work with DAC Sales, you do a lot of talking and we do a lot of listening. Our engineers bring an average of 16 years of experience, creativity, and hands-on expertise to every project. We never forget that the most important person at the drafting table or on the job is you. DAC Sales led the way on sustainability and energy efficiency, and our design process makes environmental impact and energy savings a top priority. Any HVAC system designed by DAC Sales has sustainability and energy efficiency in its DNA. As we design your sustainable, energy efficient HVAC application, we provide you with detailed drawings, personalized equipment selections, energy payback analyses and timely cost projections. Have questions or concerns? You will always know just who to call – your personal DAC Sales Engineer.We’re here for you. Give us a call:
In 1994, Rick McGinley from DAC Sales designed an air-to-air dehumidification unit for the George R. Austin Intermediate School (Freetown-Lakeville Intermediate School). The unit was supplied by Des Champs and was state of the art, for the time. It utilized two air-to-air plate exchangers, a modulating re-circulation, and outside air dampers to regulate the outside air volume to the precise amount required for humidity control. This unit conveniently provided minimum outside air flow at the time when heating costs would be highest. Code ventilation rates were still maintained with a minimum set point on the dampers.
In 2016 Craig Ashman, DAC Sales Engineer, was contacted by SED Associates of Boston to discuss the replacement of this original unit. The replacement would have to be accomplished with minimal disruption to existing structure and operations. If possible, existing duct work and roof curbs were considered to make the transition smoother.
It was determined that the most cost effective piece of equipment, both first cost and operating cost, was the Seresco 18 ton Protocol Series unit. A custom roof curb adapter was also designed and furnished to accommodate unit mounting.
Roof Curb Adapter
Glycol Cooled A/C by a Fluid Cooler– About 40% of the units Seresco provides use fluid coolers in lieu of Refrigerant Based ACCU’s. This is a standard product offering in their Protocol Line of Pool Dehumidification Units. In the Pool Dehumidification Unit, Seresco provides a heat exchanger and a pumping package. In the heat exchanger, the refrigerant loop dumps the rejected heat to a glycol loop. It is then pumped to the Fluid Cooler on the roof. Piping is PVC from the Pool Dehumidification Unit to the Fluid Cooler. The Fluid Cooler distance can be nearly anything (600 feet is not a problem).
WebSentry – This application was also equipped with WebSentry, Seresco’s online monitoring, reporting and service optimization tool. The 24-7 WebSentry monitoring then allows Seresco to remotely monitor over 100 performance parameters of the dehumidifier using sophisticated algorithms to analyze and identify potential issues and maintenance requirements long before they become potential problems.
Design Advantages: There are many reasons why this type of application makes a lot of sense. The ultimate is stable indoor air conditions through fully modulating reheat.
Up to 85% less refrigerant charge – completely factory sealed
– Compliant with ASHRAE Standards 15 and 34
– Less refrigerant means LEEDS points
– Less cost to install and maintain
Eliminates all seasonal refrigeration and oil migration issues to outdoor condenser
– Decreased risk of compressor issues
– Increased performance
– Lower maintenance costs
Air cooled AC heat exchanger can be located far from unit
– Heat exchanger uses PVC instead of copper
– Simple installation with lower cost of materials and labour
5% to 7% more energy efficient than DX systems
WebSentry® Internet monitoring and control
Touch screen CommandCenter® control systems
Premium corrosion resistance
Mechanical vestibule outside the air stream on all units
– more efficient operation
– easy to service
– protects key components from moisture and chemicals in the air stream
To check for updates on the GRAIS pool, visit the district website at www.freelake.org.
We are using more and more ECM Motors and Fans in our applications (both new equipment and retrofit). There are a lot of good reasons to consider them in your HVAC designs. Below is a side by side comparison and seven good reasons to use ECM Motors and Fans.
ECM Fan Array
Fan with VFD Array
Permanent Magnets in Rotor
Squirrel Cage Rotor
No Slip Losses
Slip Losses in Rotor
Higher Efficiency and Performance
Motor Temperature Rise
Precise Motor Speed Control/
Exact Feedback from the Motor
Motor speed not well defined
Matched System of Drive & Motor
/Easy to Install
Parameter Setting of VFD/
High Efficiency: A big advantage of ECM motors is that they are significantly more efficient when compared to AC motors. ECM motors maintain a high level (65 to 75 percent) of efficiency at a variety of speeds. This is not true for AC motors operated on variable frequency drives. As a result, ECMs are cost and energy efficient and can reduce operating costs. In most cases, they use from less than one third to one half of the electricity used by traditional induction motors used in HVAC applications.
Ease of Control: ECMs are DC motors that function using a built-in inverter and a magnet rotor (no external VFD). The motor’s operation is simply controlled by software allowing customers to optimize and integrate the motor, fan and controller with the application. Features like data communications, constant volume control and variable speed control are simple to integrate.
Low Operating Temperatures: ECM motors’ high efficiency also means that the motors run “cool” and dramatically reduce the amount of waste heat produced.
Extended Life: Motor life of the ECM is extended due to its low operating temperature operation. ECMs are also relatively low-maintenance; the use of true ball bearings reduces the need for oiling, and varied start-up speeds reduce stress on mounting hardware. Less components, less trouble.
Quiet Operation: ECM motors are also quieter than traditional inefficient motors.
Wider Operating Range: ECM motors also have a wider operating range than traditional induction motors which means that one ECM motor can replace a number of induction motor models. In this way, the number of models required by a typical customer is significantly decreased, which decreases and simplifies inventory.
Compact footprint: ECM motors have a reduced footprint. They provide a significant savings in design layout for units.
Split DX pool dehumidifiers have huge refrigerant charges and that is an ugly liability for owners. There are solutions available today that completely make that liability go away. Montgomery County in MD was recently charged $100 per pound for R22. Imagine getting a bill for $10,000.00 to just recharge their 100 lb dehumidifier’s one circuit with refrigerant. Ouch!
Effective January 1 2017, the Environmental Protection Agency (EPA) requires indoor pool owners/managers to formally track and document refrigerant leaks from commercial dehumidifier HVAC systems. Section 608 of the Clean Air Act mandates that when a leak occurs, owners must maintain records including the unit’s location, leak verification test dates, all repaired leak locations, type of verification test used and their results. The purpose is to verify whether a repair was successful and that the leak was addressed, according to an EPA spokesperson. The records must be kept on site in electronic or paper form for a minimum of three years.
In July of 2015 the EPA published a document outlining the phase out plan for all HFCs. R134A and R410A are HFCs.
If a customer has an R22 system they are paying dearly anytime they have work done that implicates the refrigerant. Systems with large R410A charges are also expensive and will get worse. Systems being designed today will be implicated by the 410A phase out during their lifespan. It is essential to take steps today to reduce refrigerant related liabilities.
Because Seresco has the best solution for this issue – a product line that has the lowest refrigerant charges in the industry. No site refrigeration work needed. Reject heat outdoors through a dry cooler.
All Seresco units can be set up to reject heat outdoors to a dry cooler. The NP Series offers up to 85% less refrigerant charge than traditional split DX dehumidifier. This limits future liability on leaks and significantly reduces initial installation costs as well.
As the EPA continues to drive change in policy, Seresco will continue to bring the market products that support environmental stewardship goals while saving owners time and money.
ECM Motors and Fans have provided a practical solution to most AHU fan retrofits. There are a lot of good reasons to consider them in your HVAC designs. (7 Reasons to Use ECM Motors). Watch how simple the process can be.
Moisture carryover is present on DX or Chilled Water coils where dehumidification happens. Many people do not think it’s a problem. That is, until you have moisture running down duct work or spewing all over the inside of an air handler. After you’ve experienced that, you probably learned all of these rules regarding moisture carryover.
Capital Coil typically does not build chilled water or DX coils over 50”. For applications that call for a 96” high coil, we will build two 48” high coils and stack them with an intermediate drain pain. We do this for a couple reasons. First, the shipping & handling is far easier and there is less chance for damage before the coil even gets to the jobsite. Second, the drain pan in the bottom of the unit for a 96” high coil would be enormous. And, it would be practically “raining” off the top of a coil 96” high.
Air velocity for chilled water or DX coils should never be higher than 550 feet/min. Anything higher and you are asking for complications. You’d be surprised how many manufacturers won’t tell you that to keep you out of trouble.
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. 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 coil 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 550 ft/minute and that, of course, will cause moisture carryover problems.
Recently, in conversations with mechanical engineering and architectural specifiers about ventilation in commercial buildings, I have noticed persistent confusion over the use of the phrase “Passive House.” Developed originally by the German Passivhaus Institut (PHI), the phrase describes the concept of building airtight, well-insulated buildings that provide occupant comfort while requiring very little energy to heat or cool. The concept was first applied decades ago in single family residential structures. However house does not mean only single family residential. The confusion is especially understandable considering that the Passive House concept is relatively new in the multi-family and commercial building sectors of North America. Passive House building principles can be applied to all building typologies from single-family homes to multifamily apartment buildings, dormitories, offices, and skyscrapers.
Today the Passive House movement is promoted and managed by the Passive House Institute US (PHIUS) which has developed building standards and certifies consultants, projects and products for Passive House design. Passive building comprises a set of design principles used to attain a quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level. “Maximize your gains, minimize your losses” summarizes the approach. To that end, a passive building is designed and built in accordance with these five building-science principles:
Employs continuous insulation throughout its entire envelope without any thermal bridging
The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air
Employs high-performance windows (typically triple-paned) and doors
Uses some form of balanced heat- and moisture-recovery ventilation and a minimal space conditioning system
Solar gain is managed to exploit the sun’s energy for heating purposes in the heating season and to minimize overheating during the cooling season
The number of commercial-scale Passive House construction projects is growing, and growing fast. And this is not just a European phenomenon. In 2016, according to Canadian think-tank Pembina Institute “the growth of Passive House certified buildings in North America during the last year has been particularly dramatic, more than …doubling the square footage.” Recently, the Massachusetts Building Code now acknowledges Passive House: PassiveHouse Planning Package (PHPP) is an Approved Alternative Energy Performance Model, for compliance with section C407 (780 CMR Chapter 13 New subsection C407.7).
As the Passive House concept continues spreading around the world, it is exciting to see the application of newer technology to meet the special ventilation requirements of Passive House buildings, providing great energy savings and occupant comfort all at the same time. Swegon, represented by DAC, manufactures a very compact and efficient Passive House certified energy recovery ventilator, the Swegon Gold unit, that has been used in Europe for many years and can ensure your project meets the PHIUS standards.
ASHRAE regulation 170-2013 has been updated with an addendum, which changes the requirements on the technology needed to humidify hospital environments, allowing the use of adiabatic humidifiers.
Historically, humidification in hospitals and particularly in operating rooms has almost always been provided by isothermal humidifiers, which produce steam. Steam is notoriously a natural disinfectant, as most pathogens are immediately deactivated when exposed to temperatures as high as 100°C; furthermore, steam is safe in terms of spreading contaminants, as it does not carry bacteria nor other microorganisms as droplets of water may.
On the other hand, steam humidification is also the most expensive in terms of running costs, as it requires a high amount of energy to bring water to boiling point and turn it into steam. When this process is performed by immersed electrode humidifiers or heater humidifiers, which consume electricity, it can become extremely costly, especially for large hospitals with high humidification loads. When available, it would be better to use gas-fired humidifiers due to the lower cost of the energy source.
A significant change to this status-quo has been made by the new ASHRAE regulation, allowing the use of adiabatic humidification such as those provided by Carel inside healthcare facilities, with important consequences on energy consumption.
The most advanced adiabatic humidifiers have reached a level of hygiene very close to steam, while bringing a huge decrease in operating costs! Isothermal humidifiers by nature consume about800 W of energy per l/h of humidity produced, while high pressure adiabatic atomisers consume just 4 W of electricity – needed to operate the pump – to deliver the same capacity.
Not all adiabatic humidifiers are suitable for healthcare facilities however: only high pressureatomisers with certain features to safeguard hygiene level are allowed. These features include the use of reverse-osmosis to treat the water, UV-C sterilisation, sub-micrometric filtration and moisture eliminators; water in the piping must be continuously circulated or drained completely if not in use.
For more information on Carel and Adiabatic Humidifiers: