Load Banks Versus Fan Heaters for Data Center Commissioning

Both load banks and fan heaters are commonly used in data center commissioning. Both produce the heat and power to stress the heating, ventilation, air conditioning (HVAC) system to simulate real-life working conditions. Any issues found during this phase can be rectified before going ‘live,’ alleviating the risks of failure during real life situations.

The load banks or fan heaters are strategically placed throughout the center to simulate the heat and power produced by the server racks and ancillaries. On a basic level, the load banks and fan heaters are doing the same thing—producing heat. However, there are big differences between the two that should be considered. The following article discusses the differences in operation and how each is suited to data center commissioning.

1. Control and Integration

Fan heaters are simple pieces of equipment that are controlled locally to select temperature/kilowatt levels with no instrumentation. Load banks, however, offer a range of local and remote options that can be upgraded to meet specific power test requirements. Furthermore, more advanced load banks have the option to integrate into building management systems. The entire test can be controlled from one location and integrated into existing commissioning systems. This is especially useful for increasingly common ‘hyper-scale’ data centers.

2. Reliability

HVAC testing often takes many hours to complete. Fan heaters tend to lack reliability and can easily overheat or fail. Due to their low cost, this is often not a huge issue, and a replacement is soon added. The failure rate of load banks is much lower due to the heavy-duty resistive elements and their rugged construction. Fan heaters can easily be integrated back into the system if one fails, but there is downtime while the replacement happens. A load bank has a much lower failure rate, and with more advanced control (like SIGMA LT) there is the opportunity to set up redundancies to allow another load bank to take over and still complete the test without any drop in power.

3. Data Capture

Fan heaters do not capture test data. Leading load banks, and particularly SIGMA LT-controlled units, have data capture functionality. The data collected is available with time stamps corresponding to applied power and line voltages. If proof of commissioning is required by the client, load bank testing is a much better option. The results can be analyzed and pulled into a report, providing full validation of the load test. Fan heaters do not offer this capability.

4. Networking

Advanced load banks have the capability to be networked together and controlled from a central point. Electrical load can be distributed to specific load banks in the network or spread out evenly. Especially in a large data center, the capability to control from a single location saves considerable time and effort. With fan heaters, operators typically need to turn each heater on individually. Doing this multiple times during a test is very time consuming, and it likely means large time delays between applying the correct loads.

5. Longevity

As you might expect, a typical load bank has a much longer working life than a fan heater. The construction and purpose are completely different. A load bank is constructed for continuous operation and for testing power supplies, while a fan heater is constructed to simply produce heat. Data center commissioning is a critical process and needs the correct tool for the job. It is not realistic to expect the longevity of a fan heater when it is not being used as intended.

6. Versatility

With the high rate of use and versatility, load banks can be viewed as a great investment. During and after the commissioning process, the same units can not only be used for HVAC testing, but also for periodic testing of diesel generators, power distribution units and uninterruptible power supplies (UPS). The load banks can stay on site and be used for many years. Although fan heaters are a cheaper alternative, once the commissioning is complete, there is often very little use for them.

7. Cost

Load banks are generally more expensive than fan heaters. However, it is important to consider labor costs and overall completion time of the commissioning process. In larger data centers there is often a requirement for hundreds of fan heaters to complete the test. Each fan heater needs to be connected and manually switched to the correct kW rating. Each time the load need changes, the process is repeated. With networked load banks, the control system can change every load bank output with the press of a button. As a result, the time for commissioning and labor requirements are drastically reduced. It is important to factor in this cost implication when deciding between the two solutions.

Summary: Determine Your Unique Factors

There are multiple variables to consider when selecting fan heaters or load banks for data center commissioning. It is important to understand the client, commissioning requirements and the level of detail needed. For hyperscale and critical data centers, load banks are the only option, but for smaller, less critical facilities, fan heaters may be sufficient.

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