ECM Fan Array – vs. 3 Phase Motor & VFD

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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

ECM Fan Array

Fan with VFD 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/
  • Complicated Installation

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.

ECM Fan-2Low 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.Standard vs. ECM Fans-1

Compact footprint:  ECM motors have a reduced footprint.  They provide a significant savings in design layout for units.

Related Blog Posts:  
Custom Air Handling Unit Design | The ECM Fan Array
Project Snapshot: WCCC UMass Data Center | Custom Air Handling Units

Featured Manufacturer:    Cambridgeport Custom Air Handling Units  using ECM motors and fans by EBM Pabst

Also see QPAC Fan Arrays for retrofit applications.

Call us for more information or a product demonstration on ECM Motors & Fans.



Large Refrigerant Charges – No More

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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.

SerescoIf 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.

When the indoor pool industry has questions, they turn to Seresco for answers and guidance. We have already published two articles on this subject;  Refrigerant Issue Heats Up and Escalating Costs for Owners of Dehumidifiers Using R22 Refrigerant.

Why is all this important to you?

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.

Related Manufacturer:  Seresco
Related Documents:  NP Series Brochure
More information on the NP Series from Seresco.  

For More Information - askRick






ECM Fan Retrofit with Q-PAC

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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.

Related Blog Posts:  
Custom Air Handling Unit Design | The ECM Fan Array
Project Snapshot: WCCC UMass Data Center | Custom Air Handling Units

Featured Manufacturer:    Q-PAC – providing custom ECM fan solutions


Call us for more information or a product demonstration on ECM Motors & Fans.





Cooling Coils & Moisture Carryover

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Chilled Water CoilsCooling Coils & Moisture Carryover

(Credit to Guest Blogger: Matt Jacobs, Capital Coil & Air)

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.

Learn more on the Capital Coil & Air

Related Blog Post:
Top 10 Things You Need to Know about Chilled Water Coils
Top 10 Chilled Water Coil Facts
Chilled Water Coil Circuiting Made Easy

More questions about chilled water coils:  





Passive House Design – What Does it Mean

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Passive House – What Does It Mean

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

Buildings designed and built to the PHIUS+ 2015 Passive Building Standard consume 86% less energy for heating and 46% less energy for cooling (depending on climate zone and building type) when compared to a code-compliant building.  PHIUS has developed climate specific standards for all of North America .

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.


Related Blog Post:
New Look DOAS Units-Less Space, Less Noise, Less Cost
Energy Efficient Make Up Air Units

More questions about Swegon GOLD RX:  





Adiabatic Humidifiers – Now OK for Hospitals

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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 notoriouHigh Pressure Humidification Spraysly 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 advHigh Pressure Humidification Gridanced 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 about 800 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.


High Pressure Humidification PanelNot all adiabatic humidifiers are suitable for healthcare facilities however: only high pressure atomisers 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:





Related Blog Posts:
Ask Rick:  What is adiabatic humidification?
High Pressure Water Atomizing Humidifier | Energy Savings
Ask Rick:  How does a high pressure atomizing humidifier work?

Indoor Pool Dehumidifier – With NO Outdoor Condenser?

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Can you build a pool dehumidification unit without a remote condenser?  

Today,  the answer is YES!   Seresco  has introduced a new revolutionary design that needs no outdoor condensing unit.  This is really ingenious; complete dehumidification with cooling and no External Condensing Unit.  Yes, correct, Seresco has now developed a unit that is a complete package providing dehumidification and cooling all in one indoor unit.



The Optional R3 Expansion Module can now be added to Seresco NE Series Dehumidifiers in sizes from 4 to 8 tons.  The module allows dehumidification and cooling capacity in one single unit.  That’s right, no outdoor condenser, just one unit.  The waste heat from the unit can be recycled to heat pool air or pool water (like typical units).  Additional heat is transferred to the exhaust air stream through a heat exchanger and exhausted to the outdoor environment.  The exhaust fan and coil are integral to the unit.  It’s simple and it works.

Awesome Features:

  • NO OUTDOOR CONDENSER – Unit provides full A/C capacity with no outdoor condenser (using an evaporative condenser in the exhaust airstream).
  • No site refrigeration work.
  • Refrigerant charge reduction by up to 80%
  • Compact – Mounts underneath NE Series main unit, adds only 18 inches in height. Can be shipped and mounted separately.

This is a real breakthrough for the industry. Call us now for selections and further information.

Related Blog Posts:
Indoor Pool Design – Reducing Refrigerant Charge by 85%
Project Snapshot – Equinox Fitness Pool Dehumidification

More questions about Seresco Dehumidification:  


Project Snapshot: 60 State Street – Field Erected AHU

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Project Name: 60 State Street – 10th Floor, Boston
 Architect: Dyer Brown Architects
Mechanical Engineer: C3 Commercial Construction Consulting, Inc.
Mechanical Contractor: Northeast Mechanical
Equipment: Custom Field Erected Air Handling Unit
Manufacturer: Custom Air Solutions by Cambridgeport
Size: 25,000 CFM
DAC Sales Engineer: David Goodman

David & Harry – DAC’s Best Site Supervision Team

Project Overview:

The new Arup offices located at 60 State Street, 10th Floor are the first to be certified for a new healthy building certification called WELL which overlaps with a number of requirements for LEED-certified environmentally friendly buildings aimed at reducing a building’s greenhouse gas emissions and water and energy consumption.  There are seven new projects in Massachusetts being designed to be WELL certified.

Natural and indirect lighting, materials, work areas, sound, food and snack choices, and HVAC all get special attention with features necessary for a more healthy work environment.  Studies prove newly remodeled office space such as this greatly increase productivity and decrease absenteeism by placing more attention (and cost) on building considerations. Read Boston Sunday Globe article.

The existing unit was very old and rusted but compact and squeezed into the mechanical space and ducts.  The new unit occupies the same footprint but the Arup Fit-out also called for more air for improved ventilation.

The 25,000 cfm unit was designed to be 100% Knock Down construction.  It was taken up the elevator in pieces and completely built in the mechanical room by the Northeastern Mechanical team with Cambridgeport supervision.  Per the WELL standard, the new unit has Pre and MERV 13 filtration, and UVC lighting was also deployed on the cooling coil to prevent any bacterial growth.   The unit also has 3 ECM fans which do not require any VFD.


Related Blog Posts:

Project Snapshot: WCCC UMass Data Center | Custom Air Handling Units


For More Information - askRick




New Look DOAS Units – less space, less noise, less cost

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Swegon GOLD RX: Air handling units with unbeatable advantages

GOLD enables designers to re-think system design. Its extra small footprint and ultra-low sound levels make it possible to place air handling units in non-traditional spaces such as in close proximity to occupied rooms. In addition to maximizing usable space, GOLD’s decentralized design also allows smaller plenums and shafts (smaller ducts), individual tenant metering, flexible tenant time scheduling and reduced sound and energy consumption. Combining both unit and controls optimization, GOLD provides unparalleled energy efficiency levels, reliable operation, and fast commissioning.

RX models include direct-driven supply air and return air fans, supply air and return air filters and rotary heat exchanger; up to 85% total energy recovery; air flows up to 16300 cfm; variable speed regulation of the rotor and cooling energy recovery.

Smallest Footprint 

The GOLD Dedicated Outdoor Air System (DOAS) unit has the smallest footprint in the market. Up to 40 sq.ft. per unit can be saved and converted to leasable area. There will be no problem getting GOLD to fit.

Lowest Operating Cost 

The GOLD has been designed to optimize the EC motors, unit specific fan design, and casing combination for a superb overall efficiency. This, coupled with wheel efficiencies of 85% and serviceability of the fan/motor and filters, delivers the lowest operating cost to the building owner.

ComfortImproved Occupant Comfort 

GOLD has the lowest overall sound power levels of any unit in its class. Units can be placed closer to the occupied space and your risk of a client complaint due to a sound problem is significantly reduced. In office buildings, GOLD helps improve employee effectiveness and attendance by improving IAQ and thermal comfort.


GOLD comes with integrated controls which have been installed in thousands of buildings across the globe. The controls are the brains behind the best-in-class efficiencies, providing unbeatable value of ease of specification, reliability, and total project cost.

Certified Passive House Component

The high energy efficiency and efficient heat recovery has awarded the GOLD RX (sizes 04-35 and 50) with a Passive House Certificate from the Passive House Institute. This makes GOLD globally unique as it is the first ventilation unit capable of high air flows (<5300 cfm) that fulfills the requirements of the passive house certification.

Learn more on the Swegon GOLD RX

Related Blog Post: Energy Efficient Make Up Air Units
More questions about Swegon GOLD RX:  





Project Snapshot: Ayer-Shirley High School | Thermal Composite – DOAS Units

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Project Name: Ayer-Shirley High School
 Architect: Symmes Maini & McKee Associates
Mechanical Engineer: Symmes Maini & McKee Associates
Mechanical Contractor: E. Armanti & Sons, Inc.
Equipment: 4 Dedicated Outdoor Air Handling Units
Manufacturer: Annexair
Size: 3,500, 5,500, 10,000 and 12,000 CFM
DAC Sales Engineer: Pat Will

Project Overview:

The towns of Ayer and Shirley, on Massachusetts’ northern border, faced precipitous student enrollment declines as a result of the closure of the Fort Devens military base a decade ago. The towns came together to form a new district and share resources, and also to maintain a critical enrollment mass.  Whereas the original 1960 building once housed over 1,000 students, the new grade 9-12 population was planned for 460 students. The Massachusetts School Building Authority prescribed a combined middle and high school. SMMA convinced the communities to rethink the logic of this assumption by thoroughly analyzing the physical attributes of the building, and then stepping back and master-planning the District’s entire portfolio of schools.

Designing for Educational Success

Small, undersized spaces on eight distinct levels separated by narrow corridors and an underutilized open air courtyard with isolated community use spaces and tiny lobbies divided the student body and after-hours public uses making the building hard to navigate and supervise. The poor condition and environment led to over 100 students choosing alternative, out-of-district school options. SMMA aimed to maximize opportunity for pupil and adult interactions, incorporating corridor learning commons; teacher planning centers; small group rooms and larger flexible classrooms, with four teaching surfaces; and flexible, mobile furniture systems into our design. The building has remained occupied during construction, requiring careful shifting of spaces to allow for seamless, uninterrupted education.


HVAC Highlights:

  • DOAS Units
  • GAS Heat
  • Enthalpy Wheels
  • Thermo-composite panel system

The units on the Ayer Shirley High School project were supplied by Annexair and incorporated their Thermo-composite panel system.  The design looked for replacement units that would weigh the same as original and provide 30% more capacity.  Weight was a key design factor.  The Annexair units are 30% lighter than traditional steel units.  So we were able to satisfy the design criteria with a lighter unit.  Additionally the units come with a lifetime warranty against corrosion.    Best of all they are the same cost as traditional steel units.

Take a look at the specification for key features.

UNIT HOUSING SPECIFICATION (Thermo-composite) The unit housing shall be no-through metal with 2’’ Thermo-Composite and foam panel construction – interior and exterior.  No-through metal construction will be inherent to all the component construction in the assembly.  All panels and access doors shall be double wall construction with R14 foam insulation for every 2” of construction.  All foam insulation must be Greenguard certified®. Unit casing will have no exterior condensation at interior AHU temperatures down to 43F while unit exterior conditions are maintained at 95 F dry bulb / 85 F wet bulb.  The panels shall be tested in accordance with SMACNA and ASHRAE 111 to have a deflection of no more than L/1150 at 10’’ and withstand air pressures up to 8” w.c with less than 1% leakage.  Fire resistance of the panel will be in compliance with UL 94.

Thermo-Composite panels shall be provided for the entire unit construction, including but not limited to, walls, doors, floors, roof, interior partitions, and electrical compartment.  The frame shall consist of anodized extruded aluminum profiles which incorporates a thermally broken construction; welded together for reinforcement and insulated for superior thermal performance.  Base structure shall be fully welded and have integral lifting lugs which can be removed once the unit is installed.  All roof and side wall seams shall be positively sealed to prevent water and air leakage.  Panels will be non-load bearing type.

Access doors shall be provided to all major components to facilitate quick and easy access. Access doors will be made from the same material as the unit casing and shall incorporate thermal break construction.

Annexair - Composite Panel - Picture1Unit shall have the entire exterior finished with a PVDF coating designed for UV resistance. Paint shall pass ASTM B117 3000-hour salt fog resistance test and ASTM D4585 3000-hour moisture condensation resistance test. In addition, paint must meet AAMA 620-02 standard for color, chalking, gloss retention, and abrasion resistance. The air handler unit casing shall be provided with a lifetime warranty against corrosion resistance under normal use.

Related Thermo-composite Panel Blog Post:

For More Information - askRick