HVAC Ductwork Design

HVAC Ductwork Design

Have you ever wondered how HVAC ductwork is designed?

There are six methods for designing low, medium, and high-pressure HVAC systems:

 

  • Equal Friction Method
  • Static Regain Method
  • T-Method
  • Extended Plenum Method
  • Velocity Reduction Method
  • Constant Velocity Method

The most commonly used method is the Equal Friction Method. This method is used for low-pressure systems found in commercial buildings. It’s distinguishable by pressure loss per every 100 ft. of duct and is designed to be the same for the entire system. A well-designed system has an average friction rate of about 0.1” of water column per 100 ft. of duct length.

After determining the desired friction rate and CFM (cubic feet per minute) of airflow for a system, an air duct calculator properly sizes the ductwork that can support these requirements. The disadvantage of the Equal Friction Method is the lack of provision for equalizing pressure drops in duct branches. This only works if the duct layout is symmetrical.

 

 

Air Duct calculator for HVAC ductwork design

 

 

Why Is Duct Design Important?

HVAC systems are comparable to cardiovascular systems. Rooftop or air handling units are the heart, and the HVAC ductwork design is the body’s arteries and veins. Continuing this example, if arteries or veins are too big or too small, issues (such as high blood pressure or a stroke) can arise.

Comparatively, if ductwork is incorrectly sized, vital issues to the units can arise. Having ductwork that is too large can lead to a low CFM (Cubic Feet per Minute) of air flow in a given space. This can cause the unit to run longer in attempt to heat or cool a space. Inversely, having too small of ductwork can lead to high velocities and static pressures. This can create a loud environment and put unnecessary stress on the system.

In conclusion, incorrectly sized ductwork negatively impacts a system’s lifespan and energy expenses. Properly sized ductwork leads to lower energy expenses, longer unit lifespans, and more comfortable environments.

 

 

How Does a Melink Technician Verify Ductwork Installation?

While on site performing a Test & Balance, Melink technicians assess if duct systems are installed correctly. They analyze the duct system in the situation where proper airflow is unattainable. Unless unit total speeds are further adjusted to deviate from the design and rectify the imbalance.

As a result, Melink technicians reference mechanical plans, duct design tables, or an air duct calculator to verify proper duct size. Afterwards, they reference this to the given amount of air flow, then compare it with the installed ductwork.

 

 

A close up of a device Description automatically generated
This picture represents how air moves in ducts. Red areas have high static pressure, and green areas show high velocity.

 

Trained technicians inspect and identify dynamic losses areas, portions of ductwork with high friction rates and static pressure.

Dynamic loss examples due to installation errors are incorrect duct take offs, failure to include duct turning vanes, long runs of flex duct, or crimped flex duct. These issues can shorten the unit’s lifespan if not corrected. For instance, these issues can average costs of $1,200 per year extra in energy expenses.

Lastly, duct design discrepancies found during a TAB are reported and photographed for the customer’s reference.

 

 


Contributed by Andy Austin, Jeremy Neff & Anna Rusconi

 

COVID-19 and Building Ventilation

Keeping your HVAC breathing through the Covid-19 pandemic.

 

The United States continues the fight against COVID-19, many reopened businesses are concerned about indoor air quality. As a result, new requirements are being implemented for the public’s safety.

Recently, New York allowed for the reopening of shopping malls but with a mandate from Gov. Andrew Cuomo: Update HVAC filters with at least a MERV-11 rating to capture the potentially airborne coronavirus particles. Likewise, Colorado’s Denver Public Schools unanimously approved Denver schools to get ventilation upgrades to help stem the spread of coronavirus. So what do these guidelines mean, and could other states follow these policies?

 

 

HVAC Filters

Minimum Efficiency Reporting Value (MERV) is used to measure the effectiveness of air filters on a scale of 1 to 16. The higher the MERV rating, the greater the filtration, i.e. the smaller the particles it can catch. The Centers for Disease Control and Prevention (CDC) recommends to improve central air filtration to the MERV-13 level (or the highest compatible with the filter rack) and to seal edges of the filter to limit bypass.

 

 

MERV filter rating for HVAC systems
Model of MERV filter ratings. (Source)

 

However, updating an HVAC system’s air filters may not be as simple as it sounds. For instance, a common factor that will get overlooked is that most HVAC systems that were designed for lower MERV filters (likely most of them) will need to be rebalanced for the new filters. The higher the MERV rating, the better the filtration but also the higher the static pressure (or resistance) that the fan must work against, resulting in a drop in airflow. The reduced airflow could cause comfort problems and even frozen coils. To prevent these issues, the airflow will need to be measured with the new filters installed, and then the fan speed will need to be increased to achieve the designed airflow.

Yet this is still not a “one size fits all” solution for all. Many HVAC units cannot handle the higher-rated filters. Using a filter with a higher MERV rating may cause the motor to burn out. This is why it is important you have a trained technician review your unit before making any changes.

 

 

Other Building Ventilation Recommendations

In addition to replacing filters, ASHRAE recommends the following actions, with the ultimate goal being consistent and frequent air changes:

 

  • Increase outdoor air ventilation (use caution in highly polluted areas); with a lower population in the building, this increases the effective ventilation per person.
  • Open minimum outdoor air dampers, as high as 100%, thus eliminating recirculation. (During mild weather, thermal comfort or humidity within a facility normally wouldn’t be affected. During extreme weather, this clearly becomes more difficult to control.)
  • Consider portable room air cleaners with HEPA filters.
  • Consider Ultraviolet Germicidal Irradiation (UVGI), protecting occupants from radiation, which is particularly in high-risk spaces such as waiting rooms, prisons and shelters.

 

 

Developing Solutions

While the experts are recommending the above items, they are not mandatory across the country. States’ policies vary. Not to mention that COVID-19 research is still developing.

 

 

COVID-19 changing building ventilation

 

The result, in the near term, is likely to be a patchwork — some commercial buildings, schools, colleges, and other facilities will make investments, while others will not. One example of an organization making the investment to fight COVID-19 is KIPP DC, a publicly funded and privately operated network of seven school campuses with 1,200 employees and 7,000 students. KIPP DC has taken huge measures, working to find the ideal system optimized to filter the coronavirus.

 

 

KIPP DC’s Coronavirus Filter System (Source)

 

 

Hire Melink to Help

Overwhelmed and not sure where to begin? Melink employs a 100% self-performing, NEBB-Certified national network of Test and Balance (T&B) HVAC technicians that can quickly deploy to assess mechanical systems, verify airflow rates in accordance with ASHRAE 62.1 standards, and perform any traditional T&B work.

We have multiple, long-standing relationships with some of the largest national restaurant, retail, hotel, and supermarket chains. These relationships began because those partners liked the idea of having just one third-party company to coordinate. Melink handles all their properties by objectively verifying that the HVAC systems were installed and are working as expected.

We are here to help you navigate the ever-changing recommendations and regulations of the pandemic. Let us help you keep your doors open while helping protect your employees, customers, and equipment. Contact us.

‘Hire a Veteran Day’ is Every Day at Melink

July 25 is National Hire a Veteran Day. At Melink Corporation, we have veterans at nearly every level of our business, and we make hiring veterans a priority year-round.

Currently, there are 12 military veterans in the Melink family. Four are in leadership roles and eight serve in roles ranging from sales to field service, via Melink’s national network of technicians. In total, veterans comprise approximately 12% of Melink Employee-Owners.

 

 

National Hire a Veteran Day - Statistics for Melink's military veteran employees

 

We have found that our military veterans are loyal, hardworking, and have a strong sense of integrity. They bring a different perspective on life, leadership, and hard work. Hiring and employing veterans offers Melink a chance to support those that have given so much for our country. It is a mutually beneficial relationship, and our veterans’ military values easily translate to Melink’s core values.

 

 

How We Hire Veterans

To help us get matched with veterans, we work with a couple recruiting firms. Originally, we started working with the firms to find the right type of candidate to fill the challenging role of a Melink Field Service Technician.

For this role, veterans seem to be a natural fit and are drawn to the position. The role requires travel, a self-reliant work ethic, and adherence to a specific code of conduct. Plus, a technician is often away from his or her family for an extended amount of time.

For me, hiring veterans is rewarding on several different levels. I feel that we understand the capabilities of these individuals and that we can translate their military experience into the civilian job market.

Due to several of us in the leadership team are veterans ourselves, we have a unique advantage when hiring veteran talent. We truly enjoy the chance to provide opportunities to those who have also sacrificed and taken up the call to serve our nation.

 

 

Meet Our Veterans

We are proud of our veterans and stand by them:

 

 

Army

 

Jon Sawyer

Matt Meyer

Mark Goodhind

 

 

 

Melink Navy veterans

 

Navy

Schyler Forcier

Jason Eckel

 

 

 

Air Force

Jonathan Perry

Ralph Conti

Eric Kelly

Kent Edmonds

 

 

 

Marines

Michael Berry

Larry Moore

Derrick Prince

Hire a Veteran Day

TOP 3 Points to Consider Before Scheduling an HVAC Balance

There are a few important items that you want to take into account before you schedule an HVAC balance. While these 3 points may seem obvious, there are many instances where a technician gets onsite and the job-site isn’t ready or they can’t access areas that they need. These tips can save time and money for everyone!

 

1. HVAC equipment is installed and operational.

This one seems like a no-brainer! However, there are always occurrences when a technician arrives onsite to perform a balance and necessary equipment either hasn’t been installed or isn’t properly operational. Examples include VAV’s or dampers that haven’t been installed, or a RTU that isn’t operational.

Ensuring that all ductwork has been completed, balancing dampers are properly installed, any grilles, registers and diffusers are installed, and the RTUs have clean filters helps make sure a technician can provide a proper air balance, as well as mitigate any potential return service costs. Making sure that all equipment (especially RTUs) has undergone a proper start-up to confirm power should always be completed ahead of Melink’s arrival.

 

2. All HVAC equipment can be easily accessed by a technician.

Another hindrance to any proper test & balance is not being able to access the necessary equipment. This includes equipment installed inside the building, as well as equipment on the roof. When working with a customer located inside a mall or shopping center, security and approved roof access becomes another added component.

Melink typically requires assured access to all applicable HVAC system equipment, including RTUs, VAVs, Exhaust Fans, dampers, etc. Access to fully open dampers, ceiling-height diffusers, and thermostats that may be in an office is necessary to properly complete the balance. Our Account Coordinators will also discuss roof access, security measures, and accessibility to ladders or lifts.

 

3. Allotting adequate time (2-3 weeks) to schedule and complete the balance.

Though some
seasons are busier (or slower) than others, our goal at Melink is to provide
every customer the same level of service excellence no matter the time of year.
This includes communication with the customer, scheduling the site visit with
one of our National Network technicians, performing the balance and working
with the customer on any punch-list items, and finally, providing a certified
test & balance report.

Our team of National Account representatives and technicians work with the customer through each step of the process. Scheduling an HVAC balance with Melink approximately 2-3 weeks out from turnover will help to ensure a proper and complete balance. It also allows enough time to work through any punch-list items or lingering comfort issues for the customer.

HVAC Systems – How to help ensure a good investment

Life of an HVAC System

Heating, ventilation, and air conditioning (HVAC) equipment is similar to your car; it can last 7-20 years! The life expectancy largely depends on the quality of the equipment, and how the equipment is maintained. Without a maintenance log of all your systems, how do you estimate the remaining ‘miles’ your equipment has left? The answer – have an independent HVAC site survey.

Benefits of Site Surveys

Performing an independent HVAC site survey before purchasing new HVAC equipment, helps to ensure you are making the right decisions. During an HVAC site survey, or HVAC audit, independent partners help you determine the current state of your equipment. To do so, your independent partner should tailor a unique scope of work to help you with your specific needs.  HVAC site surveys can be complex with much focus on the fine details, or it can be a more general inspection of all equipment. Explain to your independent HVAC partner your situation and goals, then let them help you create a plan or program that suites your needs.

Self-Performing

“Why are you underlining independent?”, you might ask; because it is vital to ensure the gathered information is unbiased. Your partner should be a true owners advocate, working while looking through the eyes of the end owner. This task may be complicated for your equipment providers, preventative maintenance providers, and internal employees, there may be a conflict of interest in reporting one outcome verses another. One other important question to ask your independent provider is – “Are you self-performing?”.

You might be thinking – “Here we go again with these underlines.”, but self-performing is just as important as independent. Performing an HVAC site survey is a quality control related process. To fully achieve a high-quality result in your HVAC site survey, you should consider using a self-performing company. A self-performing company will use 100% of their own employees to survey your equipment. Therefore, the end product, or HVAC site survey report, is created from the findings of trusted partners or direct employees.

Once the time is right to replace or repair HVAC equipment, be sure to consider having an independent partner help you along the way. We’d appreciate if you’d consider Melink Corporation. We have a national network of self-performing technicians, and have been working with national and regional partners for over 30 years! Let us know how we can help!

Stay Ahead of HVAC Problems this Spring

While many are excited to emerge from a long and cold winter and enjoy the rising temperatures that come with spring, not everyone loves the shift in seasons. Facility managers around the country dread the season change as it always brings lingering HVAC problems to the forefront. Every year during the spring and fall as temperatures are changing, buildings around the country work hard to adjust to the change in seasons as well. The HVAC systems go from cold temps outside and constant heating of the building to cooling instead, or vice versa. This dramatic change takes a toll on the building envelope and interior and can make underlying HVAC problems that went unnoticed during one season, suddenly very noticeable. Employees and paying customers alike are feeling the discomfort of hot and cold spots, condensation dripping, A/C not kicking on correctly, doors blowing open, and other annoyances.

These types of issues not only affect the comfort for your customers in the facility, they can also lead to long term maintenance and higher energy costs should they not be fixed quickly. This is where having an independent 3rd party onsite to inspect the equipment can assist. Hiring an independent company can help in identifying the underlying cause of such problems and repair minor issues that may have gone undetected for years. By having the facility inspected by a truly independent company, facility managers can know that the information they are receiving provides a truly accurate snapshot of their facility and is not biased or swayed based on loyalties. You will get real results with accurate and actionable information.

If you are experiencing any of these issues with the upcoming season change, it is recommended to have these issues investigated immediately. Prices begin to rise just as the temperature does in the summer, as construction demand is at its peak during this time. Seeing some of these issues in your building? Contact us here to talk with our team about ways to get in front of problems before they get worse!

The R-22 Phase-Out: What It Means and How to Best Prepare

What is R-22?

R-22 is an HCFC (Hydrochlorofluorocarbon) refrigerant found in older commercial and residential HVAC equipment, such as RTUs (roof top units), split systems and other equipment.  R-22 and other HCFC refrigerants are known to deplete the Earth’s protective ozone layer and contribute to harmful climate change.

 

The US has slowly been phasing
out the use of R-22 per the following phase-out schedule:

 

  • 1/1/2010:
    The US government banned the use of R-22 in new HVAC equipment.
  • 1/1/2015:
    The US government bans the production and import of all R-22
  • 1/1/2020:
    The US government will ban the use of all R-22 (with a few exceptions).  This will be the end of the road for R-22 use in the US.

NREL (National Renewable Energy
Laboratory) estimates 40 million commercial RTUs (roof top units) were
installed in the US, in the decade prior to 2010.  The US Department of Energy also estimates
that are at least 1.6 million old, low-efficiency RTUs in operation in the
US.  This means there is a huge tidal wave of R-22 equipment in
operation that will need to be replaced in the very near future.

How does the 2020 ban affect me?
R-22 costs have skyrocketed and are already more than 4X the cost/lb. of
R410A. Older R-22 units have much lower EER ratings and are as much as 50% less
efficient than current-day high-efficiency units.  In most cases, older R-22 RTUs cannot be
converted to R410A refrigerant, and the older units will need to be replaced with a new, more energy efficient, more
environmentally friendly RTUs
.  It is
already cost prohibitive to repair older R22 units, and the “fix-on-fail”,
emergency replacement philosophy will be MUCH more expensive than a pro-active
roof-sweep or planned equipment replacement program.

How can I best prepare for the phase-out, and where should I start?  I recommend companies start with an HVAC inventory of their older equipment, in addition to a detailed survey of all their facilities to verify the age and condition of all HVAC equipment, including newer and older HVAC equipment.  I also recommend involving a national or regional HVAC installation partner, and an independent, national testing, balancing and commissioning partner such as Melink Corporation to provide the unit data and a complete assessment of the entire mechanical system.  The survey should include duct-work inspections, inspection of the RTUs and exhaust fans.  Additionally, air-flow measurements should be recorded to verify proper building airflows and identify existing air-balance issues.  If the entire HVAC system is not inspected, the building will often continue to have comfort problems and building balance issues, even after the new equipment is installed.  The positive effects of the new, energy efficient HVAC equipment will not be fully realized, resulting in a lower-than-expected ROI.

 

 

  • For
    further information on HVAC surveys and other custom scopes of work, please
    e-mail [email protected]
    or call us at 513.965.7300.

Top 3 Points to Consider Before Scheduling a Balance

  • HVAC equipment is installed and operational.

This one seems like a no-brainer, but there are always occurrences when Melink arrives to perform a balance and necessary equipment either hasn’t been installed or isn’t properly operational. Examples might include VAV’s or dampers that haven’t been installed, or a RTU that isn’t operational.

Ensuring that all ductwork has been completed, balancing dampers are properly installed, any grilles, registers and diffusers are installed, and the RTUs have clean filters helps make sure that Melink can provide a proper air balance, as well as mitigate any potential return service costs. Making sure that all equipment (especially RTUs) has undergone a proper start-up to confirm power should always be completed ahead of Melink’s arrival.

  • All HVAC equipment can be easily accessed.

Another hindrance to any proper test & balance is not being able to access the necessary equipment. This includes equipment installed inside the building, as well as equipment on the roof. When working with a customer located inside a mall or shopping center, security and approved roof access becomes another added component that must be considered.

Melink typically requires assured access to all applicable HVAC system equipment, including RTUs, VAVs, Exhaust Fans, dampers, etc. Access to fully open dampers, ceiling-height diffusers, and thermostats that may be in an office is necessary to properly complete the balance. Our Account Coordinators will also discuss roof access, security measures, and accessibility to ladders or lifts.

  • Allotting adequate time (2-3 weeks) to schedule and complete the balance.

Though some seasons are busier (or slower) than others, our goal at Melink is to provide every customer the same level of service excellence no matter the time of year. This includes communication with the customer, scheduling the site visit with one of our National Network technicians, performing the balance and working with the customer on any punch-list items, and finally, providing a certified test & balance report.

Our team of National Account representatives and technicians work with the customer through each step of the process. Scheduling service with Melink approximately 2-3 weeks out from turnover will help to ensure a proper and complete balance, and enough time to work through any punch-list items or lingering comfort issues for the customer.

Want to learn more? Contact us today!

A Good Time For Technology

Future of Technology

“Life moves pretty fast.  If you don’t stop and look around every once in a while, you could miss it.”  In my estimation, this quote from Ferris Bueller is more relevant now than when first uttered.  We’re in a period where everything continues to speed up. We’re moving along at breakneck speed to get to the next task, the next meeting, the next event, that it’s often easier to keep your head down.  The downside is that it’s easy to miss some of the amazing things happening in the world due to technology.

Smartphones

Smartphones, for example.  In the span of just a few years they’ve managed to become a nearly indispensable tool.  Gone are the days of proud parents stuffing their wallets with photos – you now have a literal gallery at your beck and call.  Simply carrying the phone gives us the ability to capture those special moments that in years past may be missed.  Try remembering what life was like travelling to a new city before we started carrying portable GPS units in our pockets.  What would previously take hours of planning is now done in minutes (if not seconds).  That’s not to say the consequences of ‘pocket computers’ have been beneficial, but I’d argue the good outweighs the bad by a significant margin.

Furthering Technology

Imagine opportunities to create new technology.  Instead of further connecting people (like the smartphone did), think of developing the next generation of sustainability.  Advancing business capabilities to reduce the amount of energy they consume and to make facilities healthier.  To help build intelligence that create win-win scenarios for companies and consumers at the same time.   Regardless of anyone’s beliefs on climate change and why it’s happening, it’s clear that the climate is changing.  Another thing that has been clear for some time is that the resources that we have on this planet are finite.  Finally, we’ve also learned that the cheapest energy of all is the energy that doesn’t get used.

Make an Impact

Right now, there is such an opportunity available.  Melink is actively searching for an Embedded Software Engineer and an Application Developer who would like to join our family as we continue our journey towards a brighter, more sustainable tomorrow.  We’re growing our sustainable offerings. These offerings include energy-saving demand controls for commercial kitchens (Intelli-Hood), innovative geothermal solutions (Manifest), and HVAC commissioning (Test and Balance). Melink is about to release an innovative new building health monitor (PositiV) and has more innovation on the way.  We’re also creating an awesome Portal that will connect our employees, technology, products, and customers with a clean, intuitive interface. This will create new applications to expand the reach of our hardware and improve the work-life balance of our employees.  Help us build the new tomorrow.

Apply online here

Considerations for a Successful HVAC Equipment Upgrade Program

Have you ever replaced old HVAC equipment just to find that, after spending a lot of money, the comfort issues you were experiencing previously are still there?  Or you now have new problems that weren’t there before?  Your HVAC operates as a complete system, and the new equipment is only as good as its installation quality and the existing system it is connected with.  Here are some tips to help you get the most out of your HVAC equipment upgrade program.

  1. First, be proactive.  Get ahead of HVAC issues before they get worse or before they occur at all.  The more proactive you are, the lesser the negative impacts to your facilities operating budget, revenue, customer relations, and human resources.  On the flip side, with a fix-on-fail approach, you deal with costly emergency repairs, you have high energy costs from inefficient equipment, your revenue and customer relations suffer as uncomfortable customers take their business elsewhere, and your human resources incur lost productivity and even turnover of employees due to uncomfortable/unhealthy working conditions.  Not to mention the effect on your stress level when you have to deal with HVAC breakdowns!
  2. Start with a site survey.  You need an accurate inventory of your existing HVAC equipment, so you can make decisions on what to do with it.  Be clear about what information you need to have collected from the field, information that will enable you to make a thorough evaluation and meaningful recommendations.  Examples include equipment age, condition, features, operating measures, and so on.  Remember that your HVAC is a system, made up of many components all working together.  The focus can tend to be limited to the heating/cooling equipment, but there are also other pieces of the system that are very important, such as exhaust fans, ductwork, air grilles, and controls, to name a few.  Issues with these other components could limit the effectiveness of any new heating/cooling equipment.  The system is only as good as its weakest member.
  3. Assess the data.  Review the data returned from the site surveys to assess the overall scale and scope of your upgrade program.  Determine your trigger points for repair versus replacement, such as equipment age, condition, and efficiency.  This is the methodology that will help you to objectively decide whether you will continue to invest in a piece of equipment or replace it altogether.  In grading the equipment, this could be a simple, Green – Yellow – Red system of classification.  Green meaning ‘do nothing’, the equipment is good as-is.  Yellow meaning ‘repair’, the equipment has some issues that can be corrected at relatively low cost.  Red meaning ‘replace’, the equipment has completely failed or is no longer worth investing in.
  4. Prepare a scope of work.  Apply the previously prepared methodology to your entire equipment inventory.  This then becomes your scope of work for each site.  Put the scope in writing and be clear about your expectations.  Your equipment suppliers and installation contractors will need this scope in order to provide you with accurate estimates of cost and lead time.  This advanced planning, budgeting, and coordination will help to ensure the subsequent execution of the work goes smoothly.
  5. Consider the timing.  Equipment suppliers and installation contractors tend to be busiest in the summer and early fall months when construction activity peaks.  Avoiding these times helps to ensure you have the support you need, and your costs may be lower.  Plus, upgrading before summer helps to prepare your facilities to handle the hot/humid weather ahead.  Any temporary outages of heating/cooling that may occur while equipment is being repaired or replaced is less impactful on the facility operations during times of milder weather.
  6. Vet your partners.  Working with the right people makes a world of difference.  Partner with suppliers and contractors who are trustworthy and reputable.  Make sure they have experience with your type of facility and HVAC system, and are qualified for the services to be performed.  With the right team, you can accomplish most anything.
  7. Inspect the work.  After the equipment is repaired or replaced, it is imperative that it be inspected, tested, balanced, and commissioned in order to receive the full benefit of your capital investment.  This is your final assurance that you get the quality and performance expected out of your HVAC system.  When issues are uncovered during this process, be sure to have them corrected by the suppliers and contractors while they are still under warranty.  If left unaddressed, those issues will become headaches and costs to your facilities and operations teams later.

Managing an HVAC equipment upgrade program can be a daunting job.  When it is handled in a proactive and organized fashion, and includes the right partners, the results can be extraordinary.