BACnet and Digital Inputs for VFDs

If you’ve read our blog for a bit, you will have most likely realized that many of our topics come from the inquiries of customers and partners. Instead of helping just one customer at a time, we developed blog posts in order to share simple solutions to common HVAC issues.

Recently, a customer contacted us asking about an issue they were experiencing with their VFD. In their case, their VFD system would only start after a power cycle. Then, before running for some time, the VFD would ultimately stop once again – not good.   

In utilizing their system, they had been starting the drive with a contact closure on digital input 18, but also had the VFD connected over BACnet. 

In this case, where both communication and hardwired points are connected, it is possible to get multiple start or stop commands conflicting. This can result in unreliable start and stop behavior on a VFD system. This happens when the BACnet BV start point is placed on a graphic or in the schedule, while the BO is also scheduled or commanded. 

If you’re also experiencing this issue with your VFD system, here are some steps on how to remedy the situation and in order to have your VFD running smoothly once again.  

In cases where the VFD is only going to start using the hardwired point: 

Set parameter 8-01 “control site” to “[1] Digital Only”.  Now BACnet commands to start or stop the drive will have no effect, only the hardwire digital point will work. 

If this does not rectify the issues you are experiencing with your VFD, please feel to reach out to our team directly. Here at AirReps, we have a team of experts who are always ready to assist when it comes to all things HVAC.  

Things to look for when installing a VRV System

When installing a Daikin VRV (Variable Refrigerant Volume) system, there are several key factors to consider to ensure proper installation and maximize system performance. AirReps has invested in VRV field project specialists in each of our offices to make sure each job is a success. Our team is here for clients and partners to lean on for questions and guidance on how to properly install each unique system. Every job is different, and we’re great at working around the different nuances of the job.  

 

  1. Take the Daikin install and commissioning class 
  • This really is step one. It’s worth taking our certified classes, which provides attendees with the foundation to build upon for a successful installation and start-up of our equipment.  

 

  1. Correct Location for Indoor and Outdoor Units
  • Indoor Units: Install the indoor units free from obstructions that could restrict airflow. Ensure there is easy access for maintenance. Always check the install manual as each individual indoor unit has variations in clearances.  
  • Outdoor Units: Place outdoor units in areas with sufficient air flow, avoiding locations that might cause the unit not to breathe properly. Always refer to the install manual. 

 

  1. Refrigerant Piping Layout
  • Work closely with AirReps to ensure the design intent is met. These systems are carefully designed on paper; we need to work closely to make sure the layout of the piping in the building will avoid unnecessary traps or breaking piping rules.  

 

  1. Condensate Management 
  • Outdoor units- Keep in mind that these units will go into defrost mode and produce a substantial amount of condensation in the wintertime. Ensure there are clear paths for the condensation to travel 
  • Indoor units- Follow local code for disposal of condensation. Ensure that condensation can flow freely and that there are no obstructions in the piping network.  

 

  1. Electrical Connections
  • Ensure proper electrical connections according to Daikin’s guidelines and local codes. Proper grounding and protection against power surges are essential to avoid damage to the system. For the low volt wiring portion, 18-2 stranded, non-shieled copper wiring is required. No splices of any kind. Refer to the installation manuals.  

 

  1. System Pressure Testing
  • Before charging the system with refrigerant, perform a pressure test to check for leaks in the refrigerant lines. This is critical for ensuring system efficiency and preventing refrigerant loss. For Daikin VRV 3 equipment, you can pressure test to 450 psi if you have a FXTQ fan coil(s), without FXTQ’s, 550 psi is permitted.  

 

  1. Correct Refrigerant Charge
  • Charge the system with the correct amount of refrigerant as per the Daikin specifications. Overcharging or undercharging the system can lead to poor performance or system failure. Work closely with AirReps on this, we’ll give you the accurate trim charge based off of your actual pipe lengths.  

 

  1. Clearance for Maintenance
  • Ensure that there is enough space around the units, both indoor and outdoor, for future maintenance and service. A minimum clearance around the units should be followed to allow for airflow and technician access. 

  

For any additional questions about your commercial HVAC system, Daikin VRV, or any other products from our lineup of manufacturers, contact our AirReps HVAC experts at [email protected] today! 

VRV Process Step 1-The design

One thing I’ve always been a fan of is a well-developed process. Whether working toward a personal goal and taking the necessary steps to achieve that goal, the process is always the fun part for me. The many steps involved in making a VRV system successful is a process; one where every part of it is extremely important.

In this blog post, I will explain, step by step exactly what it takes to make a VRV system successful, from start to finish, and ultimately, make a VRV system successful for the end users.

The first step in the AirReps VRV process is the design. The design is critical! If the design is off, the equipment will struggle in various fashions, and will ultimately become a detriment to everyone involved.

Below are the “Big 7,” seven factors to look out for when designing a VRV system. There are many nuances to this process and work, and the most important takeaway should be to reach out and work with us at AirReps on every facet of this process. The earlier we are involved, the more we can do to ensure that your specific HVAC needs are filled quickly, efficiently, and in the most cost-effective way possible.

We’re here to help and want all parties to be successful in this process.

 

1. Proper Load Calculation/Block Load Considerations

It’s crucial to conduct an accurate load calculation. This step is the foundation of the design process. The cooling and heating demands of the space must be carefully calculated, considering factors such as building orientation, insulation levels, occupancy, equipment heat load, and local climate conditions as well as a block load calculation.

By using the correct load calculation methods, you can determine the required capacity for the outdoor unit and the number and size of the indoor units. Overestimating or underestimating these values can lead to inefficiency, higher operational costs, and insufficient comfort levels, as well as equipment failures. It’s critical to be as precise as possible with the load calculation, we often see these systems drastically oversized with the assumption that these systems can turn down enough due to them being inverter driven. This assumption can be fatal for the equipment.  

 

2. Indoor Unit Selection

Daikin offers a wide range of indoor units designed for various applications, from ducted to wall-mounted and ceiling-mounted units. Choosing the right type and size of indoor units is essential to achieve optimal air distribution and comfort levels.

Factors to consider when selecting indoor units include room size, aesthetics, airflow direction, and noise levels. For example, larger spaces may require multiple ceiling cassette units for even air distribution, while smaller rooms might be better served with wall-mounted units.

An important factor to key into is the proper placement and usage of any fan coil, ensuring proper clearances for the space that are laid out in the install and engineering manuals.

 

3. Outdoor Unit Sizing

The outdoor unit is the heart of the VRV system, responsible for circulating refrigerant through the system. Sizing the outdoor unit correctly is crucial to ensure efficiency and reliability. An oversized unit can lead to higher upfront costs and reduced energy efficiency, while an undersized unit may struggle to meet the heating and cooling demands of the space. Oversized and undersized equipment can shorten the life span of the equipment.

Ensure that the selected outdoor unit can handle the total load requirements of all connected indoor units, factoring in variations in building load over time.

 

4. Piping Design

Piping is one of the most critical components in a Daikin VRV system, as it connects the indoor units with the outdoor unit. Proper piping design ensures that refrigerant flows efficiently, optimizing system performance and preventing issues like pressure loss or refrigerant leaks. The big thing for these systems is to ensure we can get oil home to the compressor, not having oil traps in the network of piping.

Key considerations for piping design include refrigerant line lengths, pipe diameter, and the number of bends or turns in the piping. Keep in mind that longer piping runs and more complex installations require additional planning to maintain system efficiency.

 

5. Zoning and Control Strategy

One of the major advantages of a Daikin VRV system is its ability to provide zoned climate control, allowing individual temperature control in different areas of a building. Proper zoning is crucial for maximizing energy efficiency and ensuring comfort in each space.

Consider the specific needs of each zone, such as occupancy patterns and usage. Also, determine whether you need a centralized control system or individual remote controllers for each zone.

 

6. Noise Levels and Sound Considerations

Noise can be a significant factor in the design of HVAC systems, especially in environments like offices, hotels, or residential areas. Daikin VRV systems are designed to operate quietly, but proper selection and placement of units can help minimize noise issues.

When selecting indoor and outdoor units, consider the noise levels in both the occupied and external areas, which is incredibly important in terms of user satisfaction.

 

7. Maintenance Access and Serviceability

Lastly, ensuring that the system is easy to maintain, and service is a key consideration in the design phase. Proper access to both indoor and outdoor units, along with clear service routes for technicians, will make routine maintenance tasks like filter cleaning/changing, refrigerant charging, and coil cleaning more straightforward.

Plan for enough space around each unit for ease of access and ensure that the system components can be accessed for troubleshooting.

Your first step when it comes to the VRV process? It should be to reach out to us to begin working together here at AirReps. We’re the experts on this equipment from all ends, from system design to hands-on technical expertise. Our team of experts at AirReps are each dedicating to creating systems that thrive for many decades down the road. It starts at the beginning of the process.

 

Making Decisions in Uncertain Times: A Long-Term Approach for HVAC and Energy Efficiency

In today’s evolving energy landscape, making the right HVAC and energy efficiency decisions is more complex than ever. Shifting tariffs, regulations, and technology create uncertainty. The key is to act based on the best available information while maintaining a long-term perspective.

 

Weighing Financial and Operational Impacts

HVAC investments—whether system upgrades, efficiency measures, or alternative energy solutions—should be evaluated on total lifecycle value, not just initial costs. While energy-efficient upgrades often require upfront capital, long-term savings in energy, maintenance, and resilience frequently justify the investment.

 

Tariff & Policy Shifts: Timing Investments Wisely

Economic conditions, inflation, and market stability all influence when to invest in building upgrades. While rising energy costs are a major factor, strategic investments in HVAC and energy efficiency must also consider broader financial conditions.

  • Inflation & Cost Stability: Delaying a project may result in higher costs later due to inflation and supply chain volatility. Investing during periods of relative market stability can lead to better pricing and project execution.
  • Incentives & Policy Timing: Government incentives, rebates, and regulatory changes can create financial opportunities that may not be available in the future. Acting before these incentives phase out can maximize ROI.
  • Long-Term Strategy: A well-planned energy efficiency investment can serve as a hedge against both operational costs and economic downturns, ensuring long-term financial resilience.

 

Making the Best Decision & Adapting When Needed

Waiting for certainty before making a decision is rarely an option. The best approach is to act based on available data while remaining flexible enough to pivot when conditions change.

For example, an energy upgrade may seem financially viable under current tariffs but could become even more beneficial if incentives improve. Successful decision-making is not rigid—it’s an evolving process that adapts to new information and opportunities.

 

Embracing Disruptions with a Strategic Mindset

Disruptions—whether from supply chain challenges, policy shifts, or changing building codes—are inevitable. However, when viewed with a long-term lens, these fluctuations often have minimal impact on well-planned projects. Businesses should prioritize efficiency, reliability, and resilience over reacting to short-term market shifts.

 

 

AirReps Approach

At AirReps, we focus on optimizing the ownership experience by helping clients make informed, strategic decisions. Whether implementing a solution today or waiting for the right opportunity, we work alongside our clients and partners to find the best path forward. True success comes from balancing efficiency, performance, and long-term value—ensuring every decision supports both financial and operational goals throughout the life of the project.