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Comparing Water Cooled Chiller Types

Comparing Water Cooled Chiller Types 1024 682 admin

Comparing Centrifugal Chillers, Screw Chillers, and Mag-Bearing Chillers: Pros and Cons

Centrifugal Chillers: Pros:

  1. High Cooling Capacity: Centrifugal chillers are capable of providing high cooling capacities, making them suitable for large-scale applications.
  2. Efficiency at Full Load: Centrifugal chillers typically exhibit excellent efficiency at full load conditions, offering energy savings.
  3. Part-Load Efficiency: Some centrifugal chillers feature variable-speed drive technology, allowing them to modulate capacity to match the cooling demand, resulting in enhanced part-load efficiency.
  4. Compact Size: Centrifugal chillers are often more compact than other chiller types, making them suitable for installations with space constraints.


  1. Limited Capacity Modulation: Traditional centrifugal chillers have limited capacity modulation capabilities, which may result in reduced efficiency at part-load conditions compared to other chiller types.
  2. Higher Sound Levels: Centrifugal chillers tend to generate more noise compared to other chiller types, making them less desirable in noise-sensitive environments.
  3. Higher Initial Cost: Centrifugal chillers are generally more expensive to purchase and install than other chiller types, making them less cost-effective for smaller applications.

Screw Chillers: Pros:

  1. Reliability: Screw chillers are known for their robustness and reliability, requiring minimal maintenance and repairs.
  2. Wide Operating Range: Screw chillers offer a wide operating range, allowing them to maintain efficiency across various cooling load conditions.
  3. Efficiency at Part Load: Screw chillers can achieve good part-load efficiency, especially those equipped with variable-speed drive technology.
  4. Lower Noise Levels: Screw chillers typically produce lower noise levels compared to centrifugal chillers, making them more suitable for noise-sensitive environments.


  1. Larger Footprint: Screw chillers tend to have a larger physical footprint compared to other chiller types, requiring more space for installation.
  2. Limited Capacity Modulation: Traditional screw chillers have limited capacity modulation capabilities, which may result in reduced efficiency at part-load conditions.
  3. Moderate Initial Cost: Screw chillers generally fall in the mid-range in terms of initial cost, making them a viable option for various applications but not the most cost-effective choice.

Mag-Bearing Chillers: Pros:

  1. Energy Efficiency: Mag-bearing chillers are known for their high energy efficiency, as the magnetic bearings eliminate friction and reduce energy consumption.
  2. Silent Operation: Mag-bearing chillers operate quietly due to the absence of mechanical friction and vibration.
  3. Reduced Maintenance: With fewer moving parts and no mechanical bearings, mag-bearing chillers require less maintenance and have a longer lifespan.
  4. Precise Capacity Control: Mag-bearing chillers offer precise capacity control, ensuring efficient operation even at varying cooling loads.


  1. Higher Initial Cost: Mag-bearing chillers are typically the most expensive option due to their advanced technology and energy-efficient features.
  2. Limited Availability: The availability of mag-bearing chillers may be limited compared to centrifugal and screw chillers, resulting in longer lead times for procurement and installation.

Factors Influencing Chiller Selection:

  • Capacity and Load Profile: Centrifugal chillers are suitable for high-capacity applications, while screw and mag-bearing chillers offer better part-load efficiency.
  • Noise Sensitivity: For noise-sensitive environments, screw chillers and mag-bearing chillers are preferable due to their lower sound levels.
  • Energy Efficiency: Mag-bearing chillers are known for their exceptional energy efficiency, making them a preferred choice for sustainable and energy-conscious projects.
  • Budget Considerations: Centrifugal chillers are typically more expensive, while screw chillers and mag-bearing chillers offer cost-effective alternatives.
  • Maintenance Requirements: Screw chillers and mag-bearing chillers generally require less maintenance and have longer lifespans compared to centrifugal chillers.

The choice between centrifugal chillers, screw chillers, and mag-bearing chillers depends on specific project requirements, including capacity, load profile, noise sensitivity, energy efficiency goals, budget considerations, and maintenance preferences. Engineers will consider these factors to determine the most suitable chiller type for their particular application, weighing factors such as capacity modulation, sound levels, initial cost, energy efficiency, and maintenance requirements. It is recommended to consult with a qualified chiller specialist or HVAC engineer to select the optimal chiller type for each unique project.

Troubleshooting Scroll Compressors

Troubleshooting Scroll Compressors 960 1280 admin

Troubleshooting a Scroll Compressor in a Rooftop Unit or Split System: A Technical Guide for Building Owners in Hot Atlanta Summers

As a building owner in Atlanta, you’re well aware of the scorching hot summers that put your HVAC system to the test. Understanding the intricacies of troubleshooting a scroll compressor in your rooftop unit or split system becomes even more crucial. In this technical guide, we will delve into the complexities of scroll compressor troubleshooting, focusing on topics such as compressor performance, measurements, common failures, and compressor replacement. By the end, you will come to appreciate the importance of relying on a trained and insured mechanical contractor to handle these tasks, especially in the face of Atlanta’s blistering summer weather.

  1. Determining Compressor Performance: When it comes to assessing the performance of your scroll compressor, the demanding Atlanta climate adds an extra layer of importance. Begin by examining the compressor’s electrical operation, ensuring that power is reaching the unit and checking for any electrical anomalies. Once the electrical side is verified, you can proceed to evaluate the mechanical functionality of the compressor, a critical aspect given the extreme conditions it operates under.
  2. Normal Superheat and Subcool Measurements: In Atlanta’s hot summers, accurate measurements of superheat and subcooling in your comfort cooling DX system become crucial for maintaining optimal performance. Superheat, measured at the suction line, indicates the temperature increase of the refrigerant above its boiling point at a given pressure. Subcooling, measured at the liquid line, reveals the temperature decrease of the refrigerant below its condensing point. While specific values for normal superheat and subcooling can vary depending on the system, it’s essential to consult the manufacturer’s specifications or a professional, especially considering Atlanta’s sweltering climate.
  3. Common Causes of Scroll Compressor Failure: Given the intense heat and humidity in Atlanta, scroll compressors are susceptible to certain failures. Understanding the common causes can help you appreciate the need for professional assistance. These causes include: a) Insufficient lubrication: Inadequate lubrication leads to increased friction and wear, compromising compressor performance and eventually causing failure. b) Overheating: Restricted airflow, excessive refrigerant pressures, or inadequate oil return can result in high discharge temperatures, leading to compressor overheating and failure. c) Electrical issues: Atlanta’s electrical grid and system fluctuations can impact compressor performance. Voltage fluctuations, improper wiring sizes, or faulty electrical components can cause compressor failure. d) Contamination: The presence of moisture, acid, or debris can contaminate the refrigerant system, damaging internal compressor components and impacting its reliability.
  4. Determining the Type of Failure: Accurately diagnosing the specific type of compressor failure in the face of Atlanta’s summer weather requires expertise and specialized tools. Mechanical contractors perform tests such as megohm readings, amp draw analysis, and refrigerant system analysis to pinpoint the root cause accurately. Attempting to diagnose the failure without the necessary experience and equipment can lead to misdiagnosis, further damage to the system, and increased discomfort during the sweltering Atlanta summers.
  5. Procedure and Equipment for Compressor Replacement: When it comes to replacing a scroll compressor in Atlanta’s heat, professional assistance is indispensable. Here’s a brief overview of the general procedure: a) Refrigerant recovery: Properly recovering the refrigerant from the system using approved equipment ensures environmental safety and legal compliance. b) Compressor isolation: Isolating the failed compressor from the refrigerant circuit by closing valves or using isolation tools prevents further damage to the system. c) Compressor removal: Disconnecting electrical connections and removing mounting brackets allows for the safe extraction of the compressor. d) Preparation for replacement: Thoroughly cleaning the system, replacing any contaminated or damaged components, and preparing the new compressor for installation. e) Compressor installation: Carefully installing the new compressor, ensuring proper alignment and connection of all components, is crucial for reliable operation in Atlanta’s demanding climate. f) Evacuation and charging: Evacuating the system to remove contaminants and moisture, followed by charging with the appropriate refrigerant and fine-tuning for optimal performance. g) System testing: Conducting rigorous tests, including leak checks and verifying proper superheat and subcooling values, guarantees the system’s reliability and efficiency in combating Atlanta’s hot summers.

Navigating the technical aspects of troubleshooting a scroll compressor in your Atlanta building’s HVAC system can be daunting. Given the challenges presented by the scorching summer weather, it becomes evident that relying on a trained and insured mechanical contractor is essential. Their expertise, experience, and specialized tools ensure accurate diagnosis, effective resolution of scroll compressor issues, and optimal performance in Atlanta’s demanding climate. Trusting professionals to handle these complex tasks guarantees your equipment receives the necessary care, minimizes risks, and ensures your building remains cool and comfortable even during the hottest of Atlanta summers.

Phasing Out of R-410A and the Introduction of New Refrigerants

Phasing Out of R-410A and the Introduction of New Refrigerants 1024 768 admin

Navigating the Transition: Understanding the Phasing Out of R-410A and the Introduction of New Refrigerants

Introduction: As a commercial mechanical contractor, part of our responsibility is to keep our clients informed about changes in the industry. One significant shift currently taking place is the phasing out of R-410A, a widely used refrigerant, and the emergence of newer, slightly flammable refrigerants. In this article, we will delve into the reasons behind this transition, address concerns regarding fire hazards, and shed light on the equipment and training requirements associated with these new refrigerants.

  1. The Phasing Out of R-410A: R-410A has long been the go-to refrigerant for air conditioning and heat pump systems due to its high energy efficiency and environmental friendliness compared to its predecessors, such as R-22. However, its high global warming potential (GWP) has prompted a shift toward more environmentally sustainable alternatives. Here’s what you need to know:

a. Environmental Impact: R-410A has a GWP that contributes to climate change when released into the atmosphere. In response, regulatory agencies worldwide are mandating the phase-out of high-GWP refrigerants to mitigate their environmental impact.

b. Global Agreements: The Kigali Amendment to the Montreal Protocol, a global environmental agreement, calls for a reduction in the production and consumption of hydrofluorocarbon (HFC) refrigerants, including R-410A. This agreement aims to limit global warming potential and transition to lower-GWP alternatives.

  1. Introduction of Newer, Slightly Flammable Refrigerants: To meet the growing need for environmentally friendly options, manufacturers are introducing newer refrigerants with lower GWPs. Some of these replacements, such as R-32 and R-454B, are classified as mildly flammable. Let’s address common concerns surrounding these refrigerants:

a. Fire Hazard: While the term “flammable” might raise concerns, it’s essential to understand that newer refrigerants are classified as slightly flammable. When used in HVAC systems, these refrigerants pose a very low fire hazard, especially in properly designed and maintained equipment.

b. Safety Precautions: Manufacturers have developed refrigerant blends with enhanced safety features, including reduced flammability and enhanced ignition resistance. The design and construction of equipment using these refrigerants adhere to strict safety standards to minimize any potential risks.

  1. Equipment and Training Requirements: To ensure safe installation and maintenance of equipment using these newer refrigerants, some additional considerations come into play:

a. Equipment Compatibility: Not all existing equipment is compatible with the newer refrigerants. It is important to consult with a knowledgeable mechanical contractor to determine if the equipment can be retrofitted or if replacement is necessary to accommodate the new refrigerants.

b. Training and Certification: Working with mildly flammable refrigerants requires specialized training and certification for HVAC technicians. Contractors and technicians should receive proper education on handling, installation, servicing, and leak detection procedures specific to these refrigerants.

Conclusion: The HVAC industry is undergoing a transition towards more environmentally friendly refrigerants, necessitating the phasing out of high-GWP options like R-410A. The emergence of newer, slightly flammable refrigerants provides greener alternatives, accompanied by enhanced safety features. It is crucial for commercial mechanical contractors and their clients to stay informed about these changes to make informed decisions and ensure compliance with regulations.

While mildly flammable refrigerants do not pose significant fire hazards, it is essential to follow safety guidelines, adhere to equipment compatibility requirements, and engage trained technicians for installation and servicing. By staying proactive and working with knowledgeable contractors, clients can embrace these changes and benefit from the increased energy efficiency and reduced environmental impact offered by these new refrigerants.

Together, we can navigate this transition towards a more sustainable future for the HVAC industry.

Note: It is important to consult the specific regulations, guidelines, and recommendations provided by regulatory agencies, manufacturers, and industry associations for detailed and up-to-date information regarding refrigerant transitions, safety protocols, and equipment requirements.

Corona Virus (CoVid-19) Services, Atlanta

Corona Virus (CoVid-19) Services, Atlanta 810 374 admin

The Corona Virus is a real threat to health and safety across the globe. The CDC is working diligently on fighting this virus. More info on their work can be found on the CDC’s website. This virus has the world’s attention, and has left many people asking “what can I do?” The CDC has issued guidance for schools, at work, and at home.

For facilities around the Atlanta Area- there are some solutions and services that we offer, that you should be aware of.

Willis Mechanical, based right here in the Atlanta area, has products and services that may help you prevent, minimize, and/or control Corona Virus. Willis Mechanical is proud to offer the following products and services:

  1. Willis Mechanical can install equipment in almost any type of HVAC system that not only kills viruses and microorganisms in the HVAC system , it also tested to kill them in the conditioned air, and on hard surfaces in contact with the conditioned air. This technology has been independently tested to kill 99% of living bacteria and viruses from a sneeze within 3ft of the source. We have had great success with this equipment in the past. (contact us for manufacturers info and test results)
  2. Willis Mechanical can provide HVAC technician teams in full Virus PPE (full face respirators and full tyvek suits) to install, repair, inspect, and maintain your HVAC systems in sensitive areas. Need those air filters changed in isolation rooms? Units cleaned with anti-viral cleaners? Airflow in these spaces is critical. We can help you maintain it.
  3. Willis Mechanical can provide a decontamination station for it’s employees and equipment. This station allows for safe and sterile exiting procedures for our team and equipment and allows for prolonged deployment of personnel to one site (medical facilities, isolation buildings, etc).

The team here at Willis Mechanical hopes this virus is eradicated quickly. But if you are wondering how your school, office, military base, or factory will protect itself and keep its equipment running- contact us and we will figure out how we can help.


HVAC Importance in the Healthcare Industry

HVAC Importance in the Healthcare Industry 1024 605 Amy Gasca

HVAC Importance in the Healthcare Industry

The healthcare industry does not have the luxury of skimping on their HVAC system. The health and lives of patients are in the hands of a facility that is expected to maintain its environment at the best standards possible. Failure to do so can result in expensive litigation, a damaged reputation, and even death.

In the United States, healthcare facilities are the second top energy consumers. HVAC performances are the largest consumer of energy for hospitals. Frost and Sullivan has a research presentation that does a great job at breaking this down in graph form:

An HVAC system goes beyond providing comfortable temperatures. It determines air quality that matters to keep patients healthy. Here are some things to consider regarding HVAC standards in the healthcare industry:

Air Quality

Contaminated air is the healthcare industry’s worst enemy. Humidity is the perfect environment for dangerous molds to thrive. Bacteria and allergens spread when air isn’t flowing appropriately. If an HVAC system is not able to properly regulate the air, this is a massive problem.  Poor air quality can make a patient’s health plummet. A neglected system will not be able to provide the proper air quality a healthcare facility needs, so it is important to make sure all HVAC components are functioning at optimal efficiency.


There are federal standards for temperature controls in a healthcare environment. Failure to adhere and report any sort of temperature variance can result in hefty fines. Exposing patients to extreme hot or cold temperatures can dramatically affect their health and is not something to be taken lightly. Maintaining a comfortable temperature for all patients is a must in a healthcare facility as each patients’ needs are important and should not be ignored.


It’s important to make sure an HVAC unit is up to standards to run efficiently at all times. The CDC’s Guidelines for Environmental Infection Control in Health-Care Facilities has a whole section dedicated to HVAC recommendations. Filters must be continuously monitored to ensure dust will not cause issues, and even as far as removing bird nests from outside components is mentioned. These little things can greatly determine an HVAC unit’s effectiveness and ability to provide the proper air to a facility. Any sort of neglect can lead to an unexpected breakdown that a facility does not have the luxury to undergo.

One of the most effective measures a healthcare facility can take is getting into contact with a HVAC contractor and getting on a preventative maintenance plan. The right HVAC contractor will take the time to properly ensure that all systems will get the utmost care that they need so patients can remain in good standings. Being on a preventative maintenance contract will ensure that patients will always be in the best care that they can be, as facility employees can focus on other priorities knowing that their air handling system is under control.


How a VFD Can Improve your HVAC System

How a VFD Can Improve your HVAC System 467 350 Amy Gasca

How a VFD Can Improve your HVAC System

Variable Frequency Drives are proven to advance energy costs when combined with your HVAC components. VFDS have been around for more than two decades and have improved and are said to be the most effective energy management tools to supplement HVAC units. Before, application was limited based on the horsepower of a system. But with time, they can now be applied to most commercial and industrial components. As VFDs continue to evolve, they become more and more powerful in energy management.

What is a VFD?

Variable Frequency Drives are a motor type that drives an electric motor by varying the frequency and voltage supplied to the electric motor. Frequency goes hand in hand with the motors speed. A VFD is helpful in managing the frequency and voltage of an electric motor’s load. This is helpful in applications that do require its electric motor to run at full speed.

How does this work in conjunction with an HVAC system?

HVAC systems are designed to operate at a consistent speed no matter the demands that are needed by its user. Building load, as you may know, is never constant. The drive motor continues to work at full capacity no matter the demand. Mechanical throttling provides a good level of control, but it is not efficient by any means. HVAC systems are designed and sized for peak load conditions but are needed less than 5% of annual operating hours. But, a VFD can be used to adjust the drive motor to gradually operate when the demand is needed rather than at full speed when it’s not appropriate. This means energy efficiency is directly affected as energy expended is dependent on the motor speed. A VFD, in short, can help the system match the load.

Which equipment in an HVAC can a VFD be applied to?

Chiller pump motors benefit from a VFD because it can moderate water flow for cooling demands appropriately by increasing or decreasing gallons per minute. Cooling tower fan motors can be manipulated by dropping speed of the fan motor to better meet the process requirements of a building.

What are the direct benefits?

Energy savings! As previously discussed, since peak load performance has been choked by the VFD, the system is not longer wastefully working at full capacity. This directly effects energy output. This will be reflected in your energy bills being drastically reduced.

Reduced stress on motor. Early motor failure is eliminated since the start/stops on the motor are reduced.

Matching of process requirements. Since most HVAC systems are designed for worst case, they are oversized for normal conditions. A VFD can help motors match load requirements more appropriately.

Noise reduction. Since fans and motors aren’t working at max capacity, you’ll notice less noise coming from your HVAC components.

Implementing a VFD to your HVAC system is a complicated process. You must first do an analysis of your existing system. For a VFD to be effective, it must be applied to a system that delivers variable flow through applying constant speed motors with mechanical restrictions. Systems that require constant flow will more than likely require a mechanical redesign for a VFD to be useful. A system that is a good candidate for VFD implementation is a pump and fan system that already has the mechanical means of reducing flow. But these means, whether they be dampers or valves, will need to be removed in lieu of VFD installation.

VFD use in retrofitting a HVAC system comes with many opportunities for a system and energy efficiency. Implementation is a detailed process that must be approached carefully in order to reap the benefits of its addition. It is important to ensure that the retrofit will yield expected savings. None the less, VFDS have rightfully earned their reputation as powerful energy savers.


Tax Break for Commercial HVAC Owners [Infographic]

Tax Break for Commercial HVAC Owners [Infographic] 150 150 Amy Gasca

Under the Tax Cuts and Job Act, businesses are now allowed to fully expense all components of an HVAC system in the same year that they are acquired rather than depreciate them over 39 years. This means huge savings.

Before, the old accounting rule only allowed for a write off of a couple percent per year because of the long depreciation time. Because the new law allows the deduction of the full cost of HVAC equipment in the year of purchase, the tax savings are substantially larger. The ACCA has an infographic that breaks down the new law in simple matters:


So, what does this mean for you?

As you may already know, R22 is being completely phased out by 2020. This means you will eventually have to replace your HVAC unit if it still requires the use of R22 refrigerant. If you do not make the switch, repairs will become costly and you are putting of the inevitable of having to replace your system.

With the new tax break, making the jump to replace your HVAC systems will be easier as you can reduce your tax bill within the same year of purchase.

If your unit is failing and costing you with the frequent repairs, you may want to go ahead and start fresh with a new system. If a new system is in your future but you aren’t sure if you want to make the decision to change, take into consideration how tax laws can change frequently. You would not want to miss out on this opportunity.




If you are ready to make the investment and save big this year on your taxes, be sure to get in touch with a trusted commercial HVAC contractor.

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