Heat balance is exactly what it sounds like: ensuring buildings maintain a steady and even temperature. In this column, I will outline steps you can take to heat-balance the multifamily-residential and commercial buildings with which you work.
Start by asking a key question: Are all of the apartments or offices within range of the desired indoor temperature (DIT), or are some running too hot and others too cool? The goal is to balance the heat comfortably throughout the entire building without wasting fuel. This is difficult to achieve, but having an energy-management system (EMS) makes it possible. EMS are known for reducing fuel use, conserving energy, and saving money, but many HVAC engineers do not realize an EMS also can be used to benchmark and applied proactively to heat-balance buildings, push for further savings, and identify and document any buildingwide or individual-unit balancing issues — and prove the results.
Next, make sure the EMS is set with a DIT at a level appropriate for your building. Then use your EMS online monitoring program to track the actual temperatures inside the building and record — over time and on average — how long the boiler must run (burn fuel) to achieve the DIT. This data is your starting benchmark. Many factors can cause runtime to be too long, such as dirty tubes, poor firing, bad heat exchange, and water leaks. If the boiler runs too long and burns too much fuel to achieve the DIT compared with “average norms” for similar buildings, your system probably is not balanced. Most buildings typically operate in an imbalanced state.
The next step is to identify and pinpoint the location of the imbalance by analyzing areas where there are a wide range of high and low temperatures. Use an accurate thermometer to measure the temperature in each apartment/office and match the measurements against those from the EMS wireless sensors. Look for reasons that a sensor would be receiving readings that are too cold or hot. Are there drapes or furniture in front of the radiator? Are windows sealed properly? Was an air conditioner installed incorrectly? Also, look for drafts created by the building's construction, such as a space's unusual exposure to wind that requires additional insulation. Of course, these are problems that can be addressed to improve the building's balance and help reduce boiler runtime. When the boiler runs for a shorter period of time, there also is less wear and tear on the system, and less electricity and water is used.
In addition to individual-unit issues, if your HVAC system is not working properly, your building will be out of balance. An EMS with an online building-monitoring/management system can provide system alerts that notify you if something is not working properly. Is the stack temperature too high? Are there steam leaks? Is there a bad coil? Is your system losing water? What is the temperature of the makeup water? Finally, how long does it take from the time the burner kicks on in response to a call for heat until it turns off in response to a pressure control/sensor? Your EMS and online monitoring system can be used together to determine the need for repairs.
For example, a 120-family, six-story building with a one-pipe steam system in Queens, N.Y., was out of balance. The first step was to check the temperature sensors in each apartment and confirm the accuracy of their readings. Each of the system's line sensors also were checked. The analysis required that a gate valve be adjusted to release the proper heat. Once adjustments were made, sensors were moved around, and the process was repeated until the entire building was balanced.
A balanced building saves money, lowers carbon emissions, provides greater comfort, and, most importantly, gives you peace of mind.
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Jerry Pindus is the founder and chief executive officer of U.S. Energy Group, developer and integrator of energy-control, monitoring, and analysis systems. He is a member of numerous professional associations, including the Community Housing Improvement Program and the Bronx-Manhattan Association of Realtors. He can be reached at firstname.lastname@example.org.
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