Construction work of all kinds is a collaborative practice, from ownership to the designer to the installer. Here at Balance Construction Consulting, we offer a unique combination of general contracting, HVAC design, and HVAC installation experience, and have seen many ways that subpar installation work can compromise careful design and bold ownership goals. We provide high-quality HVAC designs for a variety of architects and builders, from production builders to the highest end custom homes, and a question we often get as we are wrapping up the design process is whether we can suggest any best practices on the installation side. We certainly can! Starting with good design is a critical first step, but we are all relying on good installation practices to get the most out of the system.
During Construction
It is critical to start with an installer who will understand and follow the best practices recommended by the manufacturer. Reputable equipment manufacturers have a very strong incentive to make sure that end users have a positive experience, so they offer training and certification programs to make sure that installers represent them well. Make sure to work with an installer who is trained on the equipment that you plan to install.
Beyond that, there are a few best practices that we strongly recommend. One is to leave any linesets, which are the copper pipes that connect heat pump system components, under test during construction, just as a conscientious plumber would do with the water lines. Capping all linesets and pressurizing them with an inert gas like nitrogen makes leak detection during the construction process much easier; unlike water, it can be very hard to pinpoint the location of a refrigerant leak after the fact. This measure also keeps the linesets clean so that the heat pump start-up process is as smooth and reliable as possible.
Another installation best practice, which falls more on the general contractor than the HVAC installer, is to not use the system for temporary heat during construction. Heat pump systems are not designed for ruggedness, and the dust and other wear that occurs from using them during construction can significantly reduce their life. Use electric or fuel gas heat for construction, and only fire up the heat pump when you are almost done with the project.
Commissioning
With all that said, the best practices that are most often missing are not really related to the construction process: make sure all of the HVAC systems are properly commissioned, and make sure the end users are properly trained to use and maintain the systems. Proper design helps to ensure that the design meets the needs of the home, but only with proper commissioning, use, and maintenance will these systems deliver the benefits that they promise.
Depending on exactly what systems are being installed, there are several elements that go into an HVAC commissioning. The first is to make sure that any heat pumps are started up correctly. In many cases, the manufacturer will provide a commissioning checklist that your installer should be familiar with and able to provide. If not, the EPA Energy Star program provides a good option. It will include testing things like the soundness and length of the refrigerant loop, correct refrigerant charge, and all the electrical connections. Having these documents on hand demonstrates that the system was started correctly and can help troubleshooting later. The general contractor should collect these documents from the HVAC installer and provide them to the owner as part of the owner’s manual at the end of construction.
In addition to commissioning the heat pump, it’s important to verify that all air handlers are working correctly. That involves checking three primary things: static pressure, temperature change, and airflow. Static pressure is the resistance to airflow created by the duct system, and air handlers are designed to overcome a specific amount. If that amount of resistance is exceeded, the system will not perform well.
Once it is confirmed that the actual static pressure is within spec, we then need to check the airflows. A well-designed system will specify a volume of supply air at each register at a given fan speed. These airflows should be checked with a tool called a flow hood. It is common for airflows to go to the wrong spaces when a system is first started up, so the system should include devices that allow the commissioner to adjust the airflows until they match the design.
It is equally important to follow a similar process with any ventilation systems that have been installed. As with heat pump systems, some HRV and ERV manufacturers will provide some kind of commissioning template. In fact, Zehnder requires that their HRV’s and ERV’s are commissioned by an accredited third-party commissioner. Even if that is not the case, however, it is important to check that the airflows of the installed system match the airflows in the HVAC design. Many modern homes rely on the HRV to provide ventilation, and if these airflows are inadequate it can lead to mold, rot, and other issues.
User Education
Once we have made sure that all of our equipment is operating correctly, we need to turn our attention to educating our users. Modern heating and cooling systems often have more complicated controls and require more routine maintenance than more traditional systems. Modern heat pump thermostats offer the ability not only to set the heating and cooling set point, but also the system mode, fan speed, and other functions. Understanding these various system parameters will allow the occupant to get the most out of their system and improve user satisfaction.
Training users on ventilation system controls is even more critical. While most people are familiar with thermostats at least to some extent, balanced ventilation systems are often an entirely new concept. If users do not understand why the home needs ventilation, they may not even try to use the system correctly. Even then, many ventilation systems come with away settings, bypass modes, recirculation modes, night flush, and other unfamiliar settings. If users do not understand these settings, they can unintentionally interfere with the ventilation system, leading to many of the same issues as a poorly commissioned ventilation system.
Similarly, ventilation systems often require routine maintenance that is unfamiliar to most users. They usually have filters that need to be cleaned or washed, and knowing which of those things to do and how is critical. In addition, HRV’s and ERV’s contain a core and intake ducts that need to be cleaned at some interval as well. Whether the end user performs this maintenance or contracts it to others, it is critical that they understand that it needs to be done and why.
Getting a high-quality HVAC design for your project is a critical step in today’s design process, but it is only half the battle. It is equally critical to make sure that the systems perform as designed. It is certainly possible for a properly trained HVAC installer to provide this assurance and training, but in some situations a third-party commissioning is called for. Here at Balance Construction Consulting, we are more than happy to provide commissioning and training services that make sure that hard work on the design front leads to positive outcomes for our end users. Reach out to us today for HVAC design and commissioning support!
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