Month: May 2021

Oversized HVAC Systems and Design Temperatures

In recent years, there has been a shift away from oversize HVAC systems that are simply too much for the space they need to heat and cool. This is because more emphasis in building and energy codes is towards energy efficiency. Buildings are required to have more accurate cooling and heating load calculations to prevent the problems associated with oversized systems. These problems can include short cycles and poor dehumidification, among other things. However, sometimes systems are still not sized correctly.

Things Are Heating Up

One of the problems that lead to oversized HVAC systems is that the installer used the incorrect design temperatures when making their load calculation. Here is how that happens. In the winter, heat bleeds from the building to the outside. In the summer, the building absorbs heat. How much heat is gained or lost, and how fast it heats or cools, is dependant on the difference in temperature from the outside to the inside. There is a table that provides the industry standard for the proper design temperatures for each season. However, too many contractors ignore or tweak those recommended temperatures when they are making their calculations.

Temperatures are always in flux, whether inside or outside a building. How much heat a building games or loses is in flux as well, even from hour to hour and day to day. If the goal is to keep the temperature of a building at a constant, such as 72 degrees, then the difference in temperature from outside and inside will be less in the evening and morning during the summer when it is cooler. When the temperature difference goes up, then the cooling load will have to rise as well. In most cases, buildings have air conditioners that are not designed to change the amount of cooling based on the change in temperature. THis would require split heat pumps, which are not common.

Design Temperatures

This is where design temperatures come in. Since most HVAC equipment is fixed capacity, and not variable, the design temperature will help make sure your system is operating at its best. The question is, what do these temperatures represent? In Winter, the 99% temperature refers to the level that the outdoor temperature will be above for 99% of the time. This is based on a 30-year average. This means that in the climate in which the building is located, the temperature will only be below that point for 1 % of the time. For example, in hotter cites, the 99% winter design temperature may be 25 degrees or so.

In the summer, the 1% design temperature is the point that your climate will be above for just 1% of the time. In a hot place, that point could be in the 80’s, for example. In the past, there used to be 97.5  and 2.5% temperatures. Those are no longer used since the current design temperatures have become the new standard.

Contactors and Design Temperatures

In general, contractors do not like having to return to the scene of a job to adjust things if the customer complains about being uncomfortable. This is why they will install oversized systems to make sure there is always enough cooling and heating. They do not know how about the other factors that come into play with the temperature of a building, such as insulation and infiltration. Despite this, if you are having a new system installed, make sure that the contractor uses the correct design temperatures so that you will not only be comfortable, but you can avoid any issues with having an oversized system for the space that you have.

How Air Conditioning Impacts Productivity

How can the loss of commercial air conditioning impact productivity during hot summer days?

It’s hard to believe that after one of the coldest winters in history, summer is about to embark upon us, bringing with it much anticipated warmth, sunshine and the ability to be far more active outdoors. However, if you own a business, summer doesn’t necessarily equate to happier employees due to increased exposure to the Vitamin D supplied by the sun. In fact, chances are, that as a business owner, you probably already know that the loss of your commercial air conditioning for even a day can dramatically impact the productivity of your employees in a very negative way.

How Air Conditioning Impacts Productivity

Despite commercial air conditioning being created for the benefit of cooling machinery (mainly the paper press), it was quickly recognized as a breakthrough invention that benefited businesses greatly as consumers flocked to air conditioned movie theaters and stores. Hypothesizing that climate controlled environments could benefit not only machinery, but humans, as early as 1950, government researchers began studying the effects of air conditioning within the workplace. They quickly recognized the increased productivity of employees working within offices and factories that were commercially air conditioned. The initial study noted that air conditioning boosted the productivity of employees by at least 25 percent, as well as led to less employee absenteeism when compared to employees that didn’t work in air conditioned environments.

In addition to providing physical comfort to employees in various workplaces like offices and factories, commercial air conditioning also provides added health benefits as well. Medical journals are full of documented studies citing the adverse effects that extremely hot temperatures can have on a persons health. These studies include indisputable correlating data between summer heat waves and increased mortality from cardiovascular and respiratory diseases. Loss of commercial air conditioning within your business, for even a day, can attribute to high levels of frustration, stress, exhaustion and thereby, naturally, decreased productivity.

William Nordhaus, an acclaimed Economist at Yale University, created a mapping analysis that found that individuals living and operating in cooler climates generated 12 times the economic production versus their counterparts living in the hottest climates across the globe.

Humidity also plays a large role in the comfort of employees and their productivity. The loss of commercial air conditioning within a work environment can wreak havoc upon the desired humidity level, attributing to sluggish employees and diminished work output. If the weather is highly humid, air doesn’t just feel heavier, it is heavier, and moves differently. High humidity doesn’t allow the human body to evaporate sweat as easily as it can at comfortable humidity levels. Commercial air conditioners supply climate controlled comfort by including condensing units that draw the humidity out of the air as it cools the workplace down.

The loss of commercial air conditioning within your business can have devastating effects on the productivity of your employees, so as warmer weather looms on the horizon, savvy business owners should be preparing to assure that their air conditioning systems are up to par in order to avoid not just the cost of emergency repairs, but also to assure that productivity remains at an optimal level.

What To Know About Eddy Current Testing

Eddy current testing is a way for those who work with specialty metals to test for imperfections, such as cracks or gaps. These flaws are detected by electromagnetic induction. It can catch these flaws on the surface of the material, but also in the sub-surface. Not only that, but eddy current testing can also be used to measure the conductivity and thickness of a material. Here are some things that you might find interesting about eddy current testing.

Nondestructive Testing (NDT)

Eddy current testing is categorized as a nondestructive testing method. This means two things. For one, the system is reliable, safe, and cost-efficient. The other is that the testing is conducted without causing harm to the material or any parts connected to it. It will also do nothing to affect the use of them in the future. There are several NDT techniques, including simply using the eyeball test, and eddy current testing is one of the most important.

It is Vital in Everyday Life

It may surprise you to hear that eddy current testing is an important part of our lives, but it is absolutely true. Eddy current testing is used in many industries and for many of the products we interact with daily. As an example, eddy current testing is the preferred method to use for testing oil and gas pipelines, chemical manufacturing, nuclear reactors, and our local water systems. There is portable equipment for eddy current testing to perform inspections on site, such as on bridges. Public safety is greatly enhanced by using eddy current testing, which makes it important to us. Not only can it be used for those large components, but it can also be used for smaller parts that also have an impact on safety.

Different Probes Depending on the Mode

ECT uses test probes that come in several styles and sizes. They do not just have different shapes, but also have varying modes of operation. Take, for example, an absolute measurement probe. This probe creates eddy currents by using a coil. These currents then track any changes in the current field. Another probe has two coils, so that the operator can use comparisons to find flaws. If there is a coil lingering over an imperfection, and the other is over a good spot, then the operator gets a signal.

There are Several Factors That Can Affect Eddy Current Testing

Eddy current testing equipment generally comes with several settings. There is amplitude, frequency, and sensitivity, among others. These all need to be considered when performing ECT. That said, there are other factors in play as well. You must consider anything that might affect the flow of the currents, such as any properties of the material you are testing. If there are obstructions, then an adjustment to the settings may be required.

Magnetic permeability is one of those factors that can affect how easily the currents flow through a material. When measuring permeability, there can be interference created when using ferrous materials. That makes it hard to use eddy current testing for accurate results. To get over this, technicians can use magnetic saturation or different coil arrangements to get accurate readings.

When it comes to interference, even ambient room noise can cause problems for eddy current testing. The best option is to try to filter out any noise in the environment to get a good signal. There can also be issues if the part or material being tested has sharp or geometrical edges. Technicians can use a special scanning technique to overcome this.

The eddy current testing procedure is used on several materials, such as tungsten and molybdenum rods. It is an effective way to inspect materials for damage, cracking, fractures, and pitting.

If you want your HVAC system to run more efficiently, the experts at Corporate Mechanical can help. Reach out online or call 763-533-3070.

A Comprehensive Guide to Variable Frequency Drives

Variable frequency drives (VFD) are used in appliances and compressors of all sizes. They can help make electrical motors more efficient. They work by managing the frequency and the voltage so that they use energy in the most efficient manner possible. They are being used more and more as the development of the technologies has made the drives smaller and improved their performance. Here are some things to know about variable frequency drives.

AC Motor
Usually the motor for a variable frequency drive is a three phase induction. This is because such motors are generally the most economical. Less commonly used are wound rotors, permanent magnets, and synchronous motors.

Controller
A VFD has a controller that runs because of three sub-systems. Those sub-systems are the converter, the DC capacitor, and the inverter assembly. The converter stage is where the AC voltage is converted to DC voltage. The DC capacitor assembly and the inverter assembly work in tandem to initiate the three phase voltage. In 1983, the insulated gate bipolar transistor made it so that a VFD cost less and improved its amperage ratings.

Operating
VFDs have an extensive operator interface. It can start and stop the motor, as well as adjust the speed. There are types that allow for reversing the motor and even switching from manual control to automatic. VFDs are operated by either a computer network, digital controls, or the operator interface controls on the unit.

Drive Operations
A VFD will have three options for driver operations. Single quadrant operations are most common, and involve using constant or variable torque. Two-quadrant loads are needed when the torque alters its polarity but the speed is constant. For the highest performance, a four-quadrant load can handle speeds and torques that change direction and force.

Types of Variable Frequency Drives

Controlled Source Inverter
A controlled source inverter (CSI) works by using a SCR converter to convert all the incoming power to DC. CSI have a large internal inductor so that they can work efficiently and properly to handle the incoming power load. The advantages of this type of VFR are that the circuitry is relatively simple, they are very reliable, and they are capable of regeneration. Some of the drawbacks are that it relies on that large conductor, which is expensive, and that it is not compatible with multi-motor applications.

Voltage Source Inverter
Voltage Source Inverters (VSI) are similar to CSI in that the prime function is the covert power to DC by using a SCR converter section. However, VSI drives cannot regulate current, which the CSI drive can do. The VSI can create an adjustable frequency output for motors.

Pulse Width Modulation
The pulse width modulation (PWM) design is the most common drive controller. It can work with the largest variety of motors, and is very reliable. It is the most sold by manufacturers as well, so there are many brands from which to choose. As opposed the the VSI and CSI drives, PWM converts AC voltage to DC voltage. It does this by using an inverter section that also has gate bipolar transistor that are insulated. This creates a near-sine wave output. These drives are a low cost upfront, are compatible with multiple motors, and can operate through a power loss. The only issues are that it cannot regenerate, and can break down because of the switching transistors.

Benefits of Variable Frequency Drives
VFDs come with a host of benefits. For one, they are very energy efficient, in particular with regards to centrifugal load service. Estimates show that well over 60% of all used electrical energy is consumed by power motors. VFDs and other efficient technologies help to reduce that energy footprint.

Performance Control
VFDs allow you to regulate the amount of power a motor delivers. With fixed speed drive, a motor might be delivering more power than is needed. To have better process control, VFDs will regulate that power and only use as much energy as is required.

Now you know about the different types and benefits of using VFDs. Make sure to choose the right one for the job you have to do.

If you want your HVAC system to run more efficiently, the experts at Corporate Mechanical can help. Reach out online or call 763-533-3070.

The Benefits of Getting a Commercial HVAC Retrofit

The Benefits Of Getting a Commercial HVAC Retrofit

There is not a company in the world that is not looking to save energy and money. Those with older heating and air conditioning (HVAC) systems may want to replace their entire system, but might find the cost prohibitive. Luckily there is a way to save energy and costs by retrofitting your current system with add-on components. Here are some of the benefits to this practice.

Energy Saving and More

Energy savings are certainly a big benefit, but there is more that you can get out of retrofitting your system. For one, you can squeeze more life out of the old unit, which means saving your capital dollars for other things. You can also continue using the refrigerant that is already in your current unit, so there is no need to purchase any more. These retrofit add-ons will also help your HVAC system run more efficiently, which means it will heat your building faster and with less cost.

Retrofitting Options

Here are some of the different options you have for retrofitting your HVAC system. You can install more efficient screw compressors. This will lessen the amount of energy used in chilling the building. You can also use air-side economizers. These components will use outside air to help with cooling your building, as opposed to refrigerant. Supply fan speed controls assist with monitoring how hard the system works by allowing you to adjust the fan speeds to suit the time of year and the climate.

Kits For Retrofitting

Many retrofit components are available in kits. These kits make it simple for a home or building owner to retrofit their system without having to put in a lot of shopping and thought. Some kits are made specifically for certain types of systems, and others will work with any system.

How To Know If Your System Will Benefit From Retrofitting

It is not necessarily about the age of your system to decide whether it needs retrofitting. If your system is running long hours in a day, then you will save more money through retrofitting. Or, you may simply notice that your energy bills keep increasing. No matter what your situation, you can always call in a professional to inspect your system and discuss your retrofitting options.

If you want your HVAC system to run more efficiently, the experts at Corporate Mechanical can help. Reach out online or call 763-533-3070.

What to Expect During an HVAC Inspection

Getting a heating and air conditioning (HVAC) system inspection can help improve your system’s efficiency by finding any trouble spots. Once those problems have been found, then you can go about repairing them. For commercial buildings, it is best to have an inspection on a biannual basis to keep your system running smoothly and upgraded at all times. Here is what goes on during an HVAC inspection.

Checks on Safety

There are many moving parts to an HVAC system, and also a lot of heat. Gas-powered units are susceptible to fire and explosion if they are not maintained and checked properly. The technician can make sure that everything is clean and free of safety hazards. They will also inspect the already existing safety measures to make sure they are functioning properly.

Checks on Efficiency

Cleanliness will also help with the efficiency of the system, so the technician will make sure that the vents and ducts are clear of debris. Dirt and dust will also harm the air quality of a building, so they will make sure that there is not too much buildup. In some cases the inspector can handle the cleaning right away, but if the job is too big you may have to schedule a longer appointment.

Output Of Your System

The technician will also check to make sure that the system is heating or cooling the building appropriately. There is a lot that goes into making a system as efficient as possible. The components must be in good condition, well-lubricated, and installed correctly. Also, the size of the unit must be appropriate for the size of the building. If the system is not as efficient as possible, then you will notice it by the discomfort you will feel every day. You will either be too hot or cold, or you will have to turn the thermostat higher to reach the same temperature that it was at before.

No matter how new your system is, you must have it inspected regularly to make sure that it is running at its peak effectiveness. These inspections will help you keep on top of any issues that may arise to compromise the efficiency and safety of your HVAC system.

If you want your HVAC system to run more efficiently, the experts at Corporate Mechanical can help. Reach out online or call 763-533-3070.

A Guide to Pneumatic Control Systems

You may have heard of pneumatics before, but may not really know what it means. At its most basic, pneumatics involves using pressurized air or gas. A pneumatic control system helps to control an HVAC system by using compressed air. Here is how a pneumatic control system works.

Process

The compressed air used by a pneumatic control system is pushed through plastic and copper tubes. It starts from a controller, and travels to a controlling device, which is most often a damper or a valve actuator. There are sensors attached to the lines that measure any changes in temperature, humidity, static pressure, and other factors. In effect, the compressed air is the method by which all of this data is communicated. A thermostat will be connected to these lines and will regulate the air accordingly.

Actuators

Pneumatic actuators are the motors that drive the whole system. They control the valves and dampers. They are extremely durable and reliable, and are very cost-effective. There is no need for regular maintenance on these actuator types, either. In just about every factor, whether it be durability or affordability, these actuators are superior to electric actuators.

Modular Control Components

The components that make up the system provide excellent performance and versatility. These components, such as receivers, thermostats, and pneumatic relays, can be custom configured to fit your building’s needs. No matter what, they will relay the necessary data accurately regardless of how the system is configured.

Limitations

Despite it being an uncomplicated system, there are some limitations to pneumatic controls. Because of its simplicity, building managers often overlook or forget the need for quality preventative maintenance. It is not a process that can be handled by just anyone. The air supply should be checked regularly to make sure that it is clean and dry. Also, a regular maintenance program is required to inspect all components of the system. Every two years or so, components should be adjusted to make sure there is no shifting of the setpoint.

Maintenance and adjusting are best handled by professional contractors who know the ins and outs of pneumatic controls. They will make sure that your system is running smoothly and efficiently at all times.

If you want your system to run more efficiently, the experts at Corporate Mechanical can help. Reach out online or call 763-533-3070.

How To Maintain Your HVAC System

You may think that your heating, ventilating, and air conditioning (HVAC) system does not need regular maintenance, but you would be wrong, even if it is a brand new system. The fact is, not only can your system fail if it is not properly maintained, but the health of the occupants of the building can suffer as well. Besides, HVAC systems are an expensive investment, and there is no reason why you should not protect that investment with regular maintenance. Here are some steps to take when maintaining your system.

Filters

Changing the filters regularly may be the single best way to prevent illness and poor air quality. It helps prevent water from pooling and collecting mold and bacteria. Filters are rated using a system called MERV. The higher the rating, the more effective the filter. A clear filter allows the system to more easily cycle air through. If it is clogged, then it will spend more energy pushing air through the system, plus that air will be contaminated by the nasties stuck in the filter.

Do Not Allow Pooling Water

The air conditioner intake is a prime spot for water to collect, creating a breeding ground for bacteria. Cleaning back the tree line and keeping the roof clear will help keep debris and dirt from getting into the unit. The drain lines that carry condensation away from the unit should also be kept clear and free flowing.

Evaporator and Condenser Coil Cleaning

Evaporator coils collect moisture, which promotes the growth of mold. Air coming into the building passes over those coils as well, meaning contaminated air gets spread throughout the building. Coils should be cleaned using and antimicrobial cleaner. Ultraviolet lights may also be effective in preventing mold. However, most HVAC systems do not come with ultraviolet lights, so they would have to be installed afterwards, potentially using a separate power source.

The best thing for your HVAC system is to keep it running at its best at all times. That means even if it is a brand new system, maintaining it regularly and keeping it clean. This will make sure that the air in the building is not causing illness, and also ensure that the system is running as efficiently as possible.

If you need HVAC repair or want your system to run more efficiently, the experts at Corporate Mechanical can help. Reach out online or call 763-533-3070.

Researchers Look to UVGI To Improve HVAC Performance

HVAC Innovation

Researchers are looking into a new way to improve the air quality and energy efficiency of heating, ventilation, and air conditioning (HVAC) systems. A team from Penn State University have been testing whether ultraviolet germicidal irradiation (UVGI) would work to help maintain cooling coils and keep them clean.

The team went about testing the air flow, humidity, and pressure drop before and after cleaning the cooling coils with UVGI. They will then use that data to measure what the benefits would be of using it.

HVAC Operations

When an HVAC system is running, microorganisms collect on the coils that transfer heat throughout the system. These fungi and bacteria, along with other materials, can build up to a point that affect the performance of the system as a whole. More energy is used to make up for the gap in performance. Not only that, but the microorganisms are also spread into the building. The condensation that forms on heat transfer coils are what make them particularly susceptible to contamination.

What to Do

There are a few current options for cleaning the coils. They include mechanical and chemical methods. UVGI is also currently used, but because there is very little research about its effectiveness, it is not common. UVGI is a common disinfectant for other applications, but there are concerns not just about the effectiveness for HVAC systems, but also whether it negatively affects air quality. This new research is meant to make determinations on these questions.

The project is currently operating at two test sites. Not only will they be collecting immediate data, but they will also collect data over time to see if the results hold up in the long term. That way, they can see if UVGI continues to be safe and effective after several uses.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) have been working to “maximize the actual operational energy performance of buildings and facilities,” and this research coincides with that effort. The hope is that UVGI will prove to be a safe and effective cleaner for HVAC systems, and can be used more widely.

There is a movement across all industries and sectors to be more energy efficient and safer in all things. HVAC systems will continue to improve in both factors through research like this.

If you have any needs for commercial HVAC services, Corporate Mechanical can help. Reach out online or call us at 763-533-3070