Troubleshooting new construction projects presents challenges that are not always present when troubleshooting existing systems. Existing systems benefit from presumably performing properly at one time, guiding the troubleshooting process to identifying what has changed over time.

With new construction projects, the systems are being started up and tested for the first time. The root cause of performance issues may be harder to identify. In this column, I hope to share some ideas that may help in finding and solving the root cause of new construction HVAC and plumbing projects.

Slow Down To Go Fast

Troubleshooting a system that is not performing as intended on new construction projects often occurs under immense pressure shortly before turnover or immediately after the project is occupied. While the commissioning process is designed to identify issues early, many system performance issues do not present themselves until subjected to real-world conditions. 

Often, well-meaning building stakeholders attempt to make system corrections that are inconsistent with the design intent. Furthermore, these changes — often not coordinated and rarely well documented — may be initiated by the general contractor, mechanical contractor, occupants or facilities personnel. These changes introduce new issues and move the system further away from the intended operation. 

We must resist the urge to succumb to the pressure to “fix it now” and ensure we have an intentional approach to problem-solving. In one situation, the owner was convinced he understood the solution: “The equipment capacity is too small; replace it with larger equipment now!” In this instance, we recognized that we did not have reliable data and asked the frustrated owner for a two-week grace period to return the system to design conditions and collect data. 

During this period, it was agreed that only specified people would be allowed to make changes, which would be documented and time-stamped. At the end of the two weeks, with hard data in hand, we identified that the issue was that the equipment was, in fact, too large and would not be properly turned down to meet the unexpectedly low load imposed by the building. 

While the owner did not initially understand the need for the two weeks, my company ultimately gained credibility by going through a data-driven process.

Understand Design Intent 

In the design process, owner requirements are collected and documented in an Owner Project Requirements document. The engineer then creates a Basis of Design outlining how the engineer intends to meet the OPR. These documents are rarely included in the drawing and specification set that the contractor bids. 

Furthermore, changes may be made in response to cost or product availability constraints as the project progresses. It is important that these documents remain up to date because they form the foundation of troubleshooting. 

Three simple examples demonstrate the need to understand the design intent:

1. Two pumps are piped in parallel, and design flow is not achieved. Is it appropriate to turn on the second pump to meet design flow, or is the second pump intended to be redundant?

2. The owner complains of an assembly room that will not cool down below 75 degrees. The owner desires to achieve 70 degress with 200 people in the room. Are these owner expectations in accordance with the OPR? Perhaps the room is designed to meet 75 degrees with 150 people. In this instance, the room use may be inconsistent with the information the engineer was provided during design. 

3. In another instance, a hot water distribution system had 40 hose reels connected. In conversations with the owner, it was decided that no more than four hose reels would be used simultaneously during the washdown, with an allowance for one more in case of an unplanned spill. 

While this was clearly documented and never an issue, I could foresee a potential situation down the road. If the building operators did not understand the design intent, they may complain about system performance concerning hot water delivery or pressure if they tried to use more than five hose reels simultaneously. 

Understand Design Conditions

With HVAC, it is important to understand climate design conditions. Engineers do not typically design for extreme climate events simply because it is not cost-effective. We rely on ASHRAE data that defines climate thresholds. For example, it is common to design for 0.4% climate data for cooling. This is defined as not exceeding these climate values for more than 0.4% of a typical year. 

However, we are finding that heat waves seem to occur more often when these design conditions are exceeded for longer periods than predicted by historical data. In these instances, we may have to help the owner understand the conditions under which the design is intended to meet setpoint. 

The Trouble With Intermittent Issues

Systems that flat-out don’t work are sometimes easier to troubleshoot than systems that work well sometimes. It’s like when you take your car to the shop because of the noise it is making; invariably, the noise goes away when you get there. Intermittent issues often benefit from data loggers. The data loggers can track system performance changes occurring over time, even when the technician is not watching it. 

I was part of a large entertainment center project with winter heating issues because the gas burners in the large air handlers would fault and not operate until manually reset. Everything checked out fine in on-site technician visits. It was not until we monitored gas pressure with data loggers that we discovered the utility company was experiencing pressure drops in the service to the building. 

After a month of unsuccessfully trying to troubleshoot the building, we had data in hand to demonstrate to the utility company that it must correct deficiencies in its gas service. 

The Trouble With System Vs. Equipment Issues

Equipment issues can be easier to troubleshoot because they have clearly defined system performance parameters and a manufacturer that fully understands the equipment. System issues can be harder to diagnose: “All the equipment is doing what it is supposed to, but when we put them together in the system, the system is not working right.” 

While equipment manufacturers are an important part of troubleshooting, they are often not experts on the entire system. Diagnosing system issues often requires multiple subject matter experts and a strong facilitator to synthesize their contributions to identify the root cause. 

The Trouble With Troubleshooting

When we troubleshoot systems, we bring our collective years of experience to the table. It’s most challenging when something is happening that we would not have predicted and may break our previous paradigms. We have something new to learn. 

These instances benefit from experimenting. Intentionality is important. Create a plan for the system changes you want to make and the observations and data you will collect. Then review the data and formulate the next experiment to run. This process lets you pinpoint the issue and learn how the system behaves. You can observe how changing different variables affects the system’s performance. 

At the moment, troubleshooting new construction HVAC and plumbing systems can be the more stressful part of our jobs. However, these situations provide some of the best learning opportunities. The emotional investment makes learning very sticky, and we tend not to forget these stories for our entire careers. 

The best results occur when we plan our activities with intentionality and do not take shortcuts, looking for the quick fix. We must understand the design intent and conditions, and equipment and system performance. With diligence, we can put the issue behind us and apply our learnings to the next project.

Justin Bowker, PE, has been part of the engineering team at TDIndustries since 2001. He became the manager of this team in 2009, vice president of engineering in 2016, and senior vice president of engineering/virtual design and construction in 2024.