A Balancing Act: Air Balance is an important part of HVAC maintenance

When it comes to HVAC, no news is good news for restaurant facility managers. When you start hearing chatter about the building being hot and humid, drafty, smoky or uncomfortable, you know a problem has already taken root. It’s a lot like a piano being out of tune. In addition to unhappy customers and employees, these comfort issues typically are indicators of energy inefficiency within a system. So, what can facility managers do to prevent comfort and energy threats?

Identifying Common Problems

“Facility managers need to be trained on air balance and push it to their service contractors,” recommends Jeff Dover, resource manager at RFMA.

A good place to start is to gain a foundational understanding of building pressure and common HVAC deficiencies along with following seven easy steps to bring your restaurant back into tune. Most importantly, learn how to look for negative building pressure. Remember, the goal is to stay slightly positive in building pressure.

There are three methods to identify negative building pressure. The first and most reactive method is to monitor signals that your building is negative. These signs are hot/cold spots, entry doors that are hard to open, poor smoke capture, humidity, condensation dripping from diffusers and drafts.

Second, you can measure the building pressure yourself or with the help of your service contractor by using a pressure reading tool such as an anemometer to get a ballpark pressure reading. The third and most accurate method is to hire an air balance firm to check the facility’s building balance once a year. If comfort-related issues or a negative building pressure reading are observed, then an air balance needs to be scheduled.

Investigating the Cause

What causes a building to become negative or unbalanced? The usual offenders are equipment deficiencies, improper preventative maintenance programs, and adjustment errors such as kitchen staff fiddling with thermostats or service contractors opening or closing dampers.

 Here are 10 example deficiencies you or your service contractors should be on the lookout for:

  1. Exhaust fans in poor condition
  1. Supply air leaking above ceiling
  1. OA dampers improperly installed
  1. Exhaust fans not sealed to curb or hinged correctly
  1. Dirty compartment/coil in the RTU
  1. Tops of diffuser not insulated
  1. Filters improperly sized for hoods
  1. MUA not operating properly
  1. Dirty indoor/outdoor filters
  1. Worn/broken belts

7 Steps to HVAC Balance

Once you’re ready to bring a facility back into tune, there are seven easy steps to complete. These steps may be completed by the facility manager alone, but are more likely in partnership with a service contractor. To get started, pull out the facility’s previous balance report to use as a base line for data.

One Principal Engineer at a hamburger fast food chain overseeing thousands of locations explains how her team uses the air balance report to get started with troubleshooting comfort issues.

“The reports really are my first line of defense when someone says ‘Hey, my store is cold/hot/humid,’ ” she points out. “The first thing I do is pull out the T&B report and see what it says. I look at the punch list and ask was anything wrong? Not fixed? It helps when I have to remotely assess or diagnose problems.”

Whether the previous air balance report has been reviewed or not, proceed to the following steps:

  1. Ask the onsite restaurant managers what the complaints are from employees and customers.
  1. Turn on all HVAC equipment.
    • Verify thermostats are set to “FAN ON”
  1. Check building pressure with the flame test in different areas around the restaurant (Figure 3)
  1. Observe smoke capture
    • Is the hood in the correct overhang position?
    • Are there drafts along the cook line?
  1. Check for common comfort issues (hot/cold spots, entry doors that are hard to open, poor smoke capture, humidity, condensation dripping from diffusers and drafts).
  1. Inspect the equipment.
    • Are the filters clean?
    • Are the belts in good condition?
    • Are the exhaust fan wheels clean?
  1. Determine an intervention plan.
    • If some preventative maintenance actions and/or repairs need to happen, start with the service contractor.
    • If equipment is inoperable, have it repaired or replaced.
    1. If the preventative maintenance actions are in order and the problems persist, call in a certified air balance company that has experience with restaurants like yours.
Facility managers need to trust that their service contractors will notify them of airflow-related issues. Those technicians are out on the roofs and looking at the HVAC system components more than anyone else. If the restaurant has negative pressure or other out-of-tune symptoms, the service contractor needs to inform the facility manager right away. After all, you want your customers and employees to continue singing your praises. 

Air Balance Basics for Existing Facilities

We all understand the concept of the “band-aid approach” whereby you find a quick cover-up to a problem without actually investigating the root of the it.  This concept applies very frequently in the context of a Facility Manager or Building Owner wrestling with HVAC emergencies that are being caused by negative building pressure. They will tackle issues such as condensation, hot/cold spots, humidity, odor, and difficult to open doors with band-aids of increased air conditioning, dehumidifiers, wet floor caution signs, door mechanisms, air fresheners, apologizing to patrons, comping customers’ bills, and so on.  This is understandable when you’re managing 80+ facilities, all with problems that stretch far beyond just HVAC.  However it comes with a cost of spending a lot of time, money, energy, and reputation just to have the issues continuing to come back.  While balanced airflow is not a tangible product that is easily seen or touched, the consequences of an unbalanced building are very perceptible.

Facility Managers are ready to de-mystify their HVAC issues with understanding of the root causes.  Use the air balance basics below to recognize when an issue is airflow-related.

What does it mean to have a balanced airflow?

Think of a financial statement with income listed in one column and expenses in the other.  Much like a budget where you want cash coming in to be at least equal to or greater than cash going out, you typically want the air going into a building to be slightly greater than the air going out.  Similarly, think of a balanced scale.  In the graphic below, air is being drawn out of the building by exhaust fans, to remove heat and smoke from kitchen cooking appliances and foul air from the restrooms, at a rate of 4000 CFM (cubic feet per minute).  Air is also being introduced into the building through an outside air fan, to provide fresh breathing air for the occupants and to replace the exhausted air, at a rate of 4500 CFM.  The result is a slightly positive building pressure of 500 CFM (4500 – 4000 = 500), which signifies a balanced airflow.  Conversely, if the air coming into the building is slightly less than the air leaving the building, then you have a negative building pressure, which is the frequent culprit of many HVAC problems.

Which brings us to a crucial pairing to the air balance concept.  That is if balanced airflow is peanut butter, than a performance test is the jelly.

What is an air test & balance service?\
 

An air balance testing service is the process by which the performance of HVAC airflow is measured.  Once it is tested, the systems are then adjusted, or balanced, so that the air brought into a building is slightly greater than the air being pulled out of the building.  The benefit for testing and balancing being a combined service is explained by Rob Falke, President of the National Comfort Institute, “This [positive] pressure condition can be designed, but to be sure it actually happens requires air diagnostic testing.  However, it’s hard to say how great the positive pressure reading in the building will be. It depends on how tight (or leaky) the envelope of the building is, and what other pressure generating forces exist, including the wind, appliances, exhaust fans, and the stack effect of the building.”  The result is a comfortable, healthy indoor environment with an HVAC system that is optimized to perform efficiently.

 Sources:

  • Digital image. Air Concepts LLC. N.p., n.d. Web.  Nov 25 2015.
  • Falke, Rob. “How to Measure Building Pressures.” Contracting Business, 1 May 2006. Web. 25 Nov. 2015.

Talking to Kitchen Staff About Restaurant Air Balance

Muppet chef

Regarding restaurant air balance, negative building pressure costs restaurant facility managers thousands of dollars every year.  Uncomfortable kitchen staff, as well-intentioned as they may be, are often instigators of a facility’s air circulation becoming off balance.  Hot and bothered, they’ll tinker with the thermostats or other HVAC components in an effort to come into agreement with the air they are working in.  The issue is that most kitchen staff aren’t aware of the sensitivities of a balanced HVAC system and may make an adjustment that throws the system into inefficient operation, causing the entire operation to cost much more than necessary.

During your next site visit or conversation with on-site managers, restaurant facility managers should take a moment to explain the basics of air balance to kitchen staff.

Here are some points to explain:

1. The single most important thing to explain is that HVAC equipment works as “one system.”  What happens in the kitchen can and will affect the comfort in the dining areas, and vice versa.

Kitchen hood air transfer graphic

Graphic provided by Trane

2.  Explain basic building pressure.

  • Building pressure is a large factor of customer comfort, kitchen hood smoke capture, condensation issues, energy savings, door pull issues, insect issues. etc.
  • Kitchen airflow is the largest contributing factor to the overall building pressure.
  • High velocity airflow near kitchen hoods (like from a portable fan) can adversely effect the ability of those hoods to capture and remove heat and smoke.

3.  Emphasize regular cleaning of grease filters.

  • The kitchen staff and/or the building owner should ensure that all kitchen hood grease filters are being periodically cleaned.
  • They are in place to protect the exhaust duct work, exhaust fans, and the discharge area of the exhaust fans, which is typically the rooftop.
  • Grease filters can quickly become clogged if not thoroughly cleaned on a regular basis. Also, these should also be replaced immediately if they are damaged.

HVAC cover

Hiring an experienced and professional TAB firm to perform a test and balance on your HVAC system periodically can provide confidence that your systems are balanced and operating properly.  This will ensure that your kitchen staff is operating under the best conditions and that your customers are comfortable.  

Using An Air Balance Report for HVAC Upkeep

There is much hype these days in the facilities management industry about the importance of preventative maintenance, especially for critically important HVAC systems. In our experience,  we are often urgently called out to a facility because the site’s HVAC hasn’t been well maintained. While we’re happy to help, we also want to share insights so you don’t have preventable crises.

In a recent FER magazine article Realizing ROI on Planned Maintenance – author Michael Sherer quotes David Pogach, LEED GA, Longhorn Steakhouse Facilities Manager, as saying:

“We look at planned maintenance as a way of making sure equipment lasts its expected life cycle. … We know these programs work. They save money, so for us it’s not a debate of whether to spend the money now or later. We maintain our equipment.

“Planned maintenance makes the most sense for equipment that in-house staff doesn’t have the expertise or time to maintain. Most operators who have programs in place start with HVAC because putting people on the roof is a liability issue, and most foodservice employees don’t have the expertise to service HVAC systems.”

Following are ways you can use your air balance report to help start a new preventative maintenance program or audit the effectiveness of an existing one:

1)    In your report, you’ll have a list of deficiencies and recommendations for optimal operation (figure 1). First and foremost, you should schedule completion of these tasks as part of your quarterly or semi-annual preventative maintenance program.

 

2)   Another great use of a test and balance report is using the unit inspection checklists to see what should be monitored by your HVAC contractor (figure 2).

figure 2
Rooftop inspection checklist

 

3)   The report will also include unit3)  A third way to make the most of your air balance report is to use the HVAC system layout drawings to locate and inventory all equipment that needs to be maintained (figure 3). Please note that not all test and balance contractors provide this. manufacturers, model numbers, serial numbers, pulley sizes, belts sizes, motor horsepower ratings, and a large amount of other useful data which would aid in the implementation or upkeep of any preventative maintenance program.

figure 3
Building and rooftop layout

 4)   Finally, make sure your preventative maintenance programs include all of the items below. Omitting regular service on these is a leading causes of problem stores.

  • Change belts when damaged and verify proper belt tension
  • Replace filters quarterly
  • Clean outside air filters
  • Clean kitchen hood filters
  • Clean fan blower wheels
  • Clean grease traps
  • Clean evaporator and condenser coils
  • Verify thermostat settings are correct and someone onsite is trained how to adjust programming

Additional Reading

1. Realizing ROI On Planned Maintenance, Foodservice Equipment Reports Magazine, Michael Sherer, Aug 3, 2015

2. How To Read A T&B Report,  Fresh Air Blog, Derick Ramos, Aug 27, 2015

3. Planned HVAC Maintenance Adds Up to Big Savings for Retailers, Energy Manager Today, Karen Henry, May 11, 2015

What to know about choosing an air balance contractor

Due to the skill level required and equipment needed, facility managers and mechanical contractors hire professional test and balance contractors to bring buildings into balance at the end of construction, remodels, rebalances for existing buildings and equipment changes. When HVAC equipment is installed and started up, it may not function according to design specification and eventually will delineate from proper operation if not corrected. 

Facility managers and mechanical contractors also bring in TAB contractors to investigate HVAC comfort problems. Are you aware that most HVAC problems stem from poorly maintained HVAC equipment or performance assumptions?

Selecting a balancing firm can be tricky business, but it doesn’t need to be. Following are criteria for choosing a balancing contractor, based on our experience during the past 30 years. We hope our perspective will serve you.

  • Use a certified firm
  • There are two main certification organizations:
  • Look for thoroughness. Like any service, you want to be sure your vendor is concerned about the details.
  • Look for integrity. Since most of the value of an air balance is invisible, you need a vendor you can trust.
  • Experience with your industry. HVAC systems differ among restaurants, retail stores, hotels and hospitals. Make sure your balancing partner is familiar with your type of facility needs.
  • Maintain objectivity. Have a third party firm balance your HVAC system to prevent shortcuts and misreporting.
  • Hire directly. Avoid conflicts of interest by hiring the balance partner yourself.
 Air balance report necessities
  1. Air flow measurements and adjustments
  2. Punch list with images
  • Punch list items refer to discrepancies with the design prints. For example, the prints might show there is a diffuser in the rest room, but the facility does not have it.
  • HVAC equipment data
    • Make, model, serial number, fan/motor data, voltage, belt size, equipment condition, amperage, pulley size, etc.
  • Building pressurization
    • Reading of the balanced building pressure

The above list includes the basic deliverables you should expect from an air balance report. You can read our article  How to read a Melink Test & Balance Report for a visual example of an air balance report.

To prepare for the service, a balancing firm will request the design prints of the facility and inspect any previous balance reports. In many cases with existing buildings, prints and reports are unavailable. If that happens, the air balance technician will have to work from best practice measurements. This is one of many situations where having an experienced and certified balancer is an asset because of the knowledge required to do this well.

Once onsite, the balance technician will briefly talk to your management staff and ask about any HVAC-related issues they are experiencing. A common complaint of restaurant facilities is a hot kitchen, which can be indicative of a rooftop unit with dirty blower wheels or filters, as well as loose belts on a failed compressor. These complaints give the balance technician an idea of where to begin.

Next, the balancer will spend time inspecting and measuring the equipment on the roof. He or she will record RPMs and amps, check exhaust fans and look for basic adjustments. Then the balancer will go back inside to check building pressure and take measurements of the airflow. All of this data will tell the technician what he or she needs to do. After more adjusting, such as dampers or RTU belt tightness, and measuring the effects, the technician will bring the HVAC ecosystem back to design standard.

At that point, pressures and measurements are then documented in a report. In the case of a Melink balance, the technician will also check thermostats and train staff on the proper settings, if requested by the manager. Findings will be explained to the manager as well. Finally, the facility manager or project manager will receive the report after it has gone through quality inspection.

ADDITIONAL READING:
Sources:
  • DuChane, Greg. “Optimizing Air Balance Report Data.” Trane Tracks (Apr.2015): n. pag. Trane. Web.
  • “NEBB.” International Certification, High Performance Building Systems. N.p., n.d. Web. Sept.1, 2015.
  • Prager, Ron. “Demystifying HVAC: Why Test and Balance?” (n.d.): n. pag. Web. Sept. 1, 2015. 

Troubleshooting Air Balance With Mechanical Contractors

Are you still experiencing HVAC comfort or efficiency problems?  It’s time for the next level of technical HVAC skill.  Though at this point you may have realized you’re dealing with negative building pressure, you might wait on calling the air balance contractor and first become more informed about the problem with your management team.  It’s time to call in your trusted mechanical contractor (MC).

Your contractor’s first steps will be to inspect many of the same areas we advised in our previous post. These areas should include circuit breakers, thermostats, as well as the areas listed below.  In addition, you should locate any past air balance reports and confirm that all the punch list items were corrected.  With these observations and baseline data as your starting point, you or your MC can begin to formulate a hypothesis. To dig deeper into problems, check the following areas where we most frequently find the causes of HVAC comfort issues:

1.   Filters inside the unit

Dirty, old, or clogged filters will restrict airflow through the unit.  Filters should be at least replaced quarterly for a commercial unit and can be added as part of a preventative maintenance scope of work.  In the Restaurant Facility Management Association’s Facilitator Magazine, Red Lobster Facility Manager Angela Hughes writes in her article Staying On Top of Comfort Concerns, “The washable metal filters inside each makeup air fan need to be cleaned during major preventative maintenance.  These are often overlooked by HVAC preventative maintenance vendors.  Dirty filters can block airflow into the unit and greatly affect the building balance.  If the filters are damaged or missing, be sure to replace them.”

Dirty air filters

Above: Dirty Outdoor Filters

 

2.  Inspect coils inside units

Dirty, clogged, or frozen coils can also heavily restrict airflow through the unit. Mechanical contractors are equipped to unfreeze and clean coils.  Angela Hughes explains, “Dirty coils will cause the unit to freeze up and temporarily shut down, which causes stress on the compressors.”  Further, if the rooftop unit (RTU) blower compartment and/or coils are dirty, then they are likely causing reduced airflow and contaminated air.  The solution is to clean internal components of the RTU.

Frozen evaporator coil
 

Above: Frozen Evaporator Coil

Dirty RTU blower compartment

Above: Dirty Rooftop Unit Blower Compartment
 

RTU dirty coil

Above: Dirty blower wheel inside Rooftop Unit

3.   Check refrigerant levels

Low refrigerant levels can lead to uncomfortably warm temperatures. Your mechanical contractor should be equipped to refill refrigerant.

 

4.   Open up units and inspect outside air dampers

The amount of outside air is specified in the building’s design, however it is often adjusted later as a quick-fix for short term issues, leading to bigger problems in the long run.  It is common to find improperly installed and inoperable outdoor air dampers, which negatively impact the building pressure.   The dampers will need to be adjusted to proper position and outside air intakes may also need to be installed to achieve desired airflow.

Improperly installed air dampers
 

Above: Improperly Installed Outside Air Dampers (sealed closed with caulk)

 

5.   Check for negative building pressure in your facility

The tell-tale sign of negative building pressure can be found with using the door test.  A quick way of checking your building’s air pressure is to test it with a lighter or a match at an exterior door.  Crack the door open and place a lighter in the crack as pictured below.  If the flame pulls toward the inside of building, then the building is negative.

Door lighter test

 

Above: If flame pulls toward inside of building, the building is negative.

 

6.  Has your facility undergone a remodel, renovation, or a major change in equipment?

Remodels, renovations, or major equipment replacements change the distribution of airflow and requires an air balance service.  HVAC equipment installed in a building will not function at design specification at start up.  Adjusting the system to design specification requires testing, adjusting, and balancing.

These are 6 examples of what your mechanical contractor may discover in their assessment process.  If they are able to find and properly resolve the HVAC comfort or efficiency issues, then your troubleshooting may end here.  If not, you may need to consider calling in a certified test and balancing firm.  See our next post in this series for understanding what to look for in a test & balance contractor.

Additional Reading:

  1. Bringing in an Air Balance Contractor, Larry Moore, Melink Test & Balance
  2. Angela Hughes, a Red Lobster Facilities Manager with distinguished technical knowledge of HVAC systems, authored a very practical approach for FMs to self-diagnose comfort problems without prematurely spending money on contractors. Staying On Top Of Comfort Concerns
  3. For suggestions on preparing for an air balance, read Optimizing Air Balance Report Data  by Greg DuChane, Retail-Restaurant Vertical Market Director at Trane
Resources:

DuChane, Greg. “Optimizing Air Balance Report Data.” Trane Tracks (Apr. 2015): n. pag. Trane. Web.

Hughes, Angela. “Staying On Top Of Comfort Concerns.” Facilitator Magazine Apr/May (2015): 66. Restaurant Facilities Management Association, 25 June 2015. Web. 26 Aug. 2015.

Melink Test & Balance Technicians. HVAC Deficiency Images. Digital image.Melink Test & Balance. Melink Corporation, n.d. Web. 26 Aug. 2015. .

Do Any of These 4 HVAC Issues Occur at Your Restaurant?

Are you contracting out your preventative maintenance?  Unfortunately, we’ve seen a lot of restaurant managers be misled by their mechanical contractors into thinking their “building is balanced”, but still notice misreported or never- reported problems that are causing complaints from their guests.  For example, you’ve been told that air filters and screens used for the outside air intake are clean, or that belts are tight, when they are in fact loose or cracking and ready to break.  These facility problems would cost so much less if treated immediately.  For example, a $10 fan belt replacement, if not replaced by your facility management when needed can cause irreversible damage to the rooftop RTUs, along with the cost of uncomfortable guests.  These instances escalate in the summer and fall months, when outdoor weather threatens indoor comfort.

Be aware of these frequent summer sick building symptoms, so you can call out the indicators, if necessary:

  1. Humidity- Sits in the carpets or hardwood floors causing buckling, odor, and mold.  Often triggers allergies for guests.
  2. Too much exhaust and little or no fresh air-causing a negative building pressure, so anything in the outside air can come in, including bugs and pests.
  3. Condensation on windows and/or grills
  4. Entry doors hard to open- Leaving guests frustrated, or worse-assuming the restaurant is closed

All the above issues can cause a negative building pressure, allowing the outside air to infiltrate the building through every crack and crevice, causing damage that could shut a restaurant down from a health code standpoint. If you’re concerned that your building is uncomfortable or not running how it was designed to, you have the option of calling in a third party HVAC balance service who can give you an objective diagnosis of the issue, and fix it.