Before a new commercial building is commissioned, there is typically a lot of thought that goes into hot water demands. Water heating systems are designed to accommodate the building’s projected usage patterns, taking into account factors like occupancy and fixture counts.
Such planning is foundational, yet it may be insufficient for meeting the building’s needs long-term. That’s because the needs of the building are never static. Tenant turnover and evolving facility uses all contribute to shifting demand. A space once occupied by a high-traffic tenant may now see intermittent use, while other areas may experience increased load.
Even as the building and its usage patterns change, the hot water system typically doesn’t. That may mean a system that is significantly misaligned with the facility’s current needs.
Signs of Misalignment
When this type of misalignment occurs, it doesn’t necessarily manifest as a complete failure; rather, it may take the form of subtle yet persistent operating issues. Some telltale signs for facilities teams to keep an eye on include:
- Inconsistent availability of hot water during peak times.
- Temperature fluctuations at different fixtures.
- Rising energy consumption and cost, without a corresponding rise in occupancy.
- Increased wear on pumps, valves, or heating elements.
For facilities teams, it’s important to be alert to any of these issues, along with any tenant complaints about unsatisfactory hot water availability. These could all be indicators that the current system is either undersized or oversized in relation to usage needs.
Performance Consequences
Misalignment can create performance issues and operational challenges, regardless of whether the unit is too large or too small to meet the facility’s current demand.
In facilities that have reduced or redistributed occupancy, oversizing is common. Oversized systems tend to be inefficient; larger storage tanks and higher-capacity heaters may mean temperatures are maintained for water that’s never used, contributing to significant rates of standby heat loss.
This naturally drives up energy costs, but that’s just one negative impact. For example, oversizing can also contribute to water quality concerns, as more time spent in storage tanks and piping can increase the risk of water stagnation. Oversized systems also lead to short cycling, where heating equipment turns on and off more frequently. This accelerates wear on components and reduces equipment longevity.
Undersized systems can present problems of their own. Mostly, they just struggle to meet demand, especially during peak usage hours. Performance degradation can take many forms, including longer wait times for hot water, temperature drops during simultaneous use, and increased strain on heating equipment. Regardless, the effect on tenant satisfaction can be dire, particularly in applications where consistent hot water is mission critical: think restaurants, healthcare facilities, fitness centers, and spas.
Practical Steps
Both scenarios can bring about unwanted consequences, but thankfully there are practical steps facilities teams can take to evaluate and improve their system, without necessarily requiring a full system replacement.
A good place to begin is with simple data collection. Review things like usage patterns, energy consumption trends, and occupancy schedules to help identify any gaps between system performance and demand. Submeters and temperature sensors may be useful for accurate data gathering.
It also helps to assess system controls. Adjusting temperature setpoints and recirculation schedules can significantly improve efficiency. Balancing the distribution system can also be beneficial. Balancing valves or controls can help ensure consistent flow rates throughout the space, which in turn ensures a more even temperature and eliminates some of the system strain.
There are also equipment-level adjustments that can make a difference. For example, facilities teams may consider retrofitting their water heaters with variable speed pumps or segmented tanks, which enable the system to respond more dynamically to evolving demand.
Ultimately, hot water systems may become inefficient over time; that doesn’t mean they fail overnight, but it may mean they fall short of the mark operationally. Being alert to system sizing issues is a critical step toward keeping systems aligned with the building’s needs.
Cheryl Wagner is the senior manager of mechanical solutions at Bradford White Water Heaters, an American manufacturer and five-time ENERGY STAR Partner of the Year.