4 tips on HVAC
1. Factors to Consider When Choosing a Boiler and Water Heating Training Program
Just as there is a range of training formats available for boilers and water heaters, managers have options when it comes to program providers. Determining the most suitable provider for the facility depends on the manager's goals. For example, a number of different providers, such as those who conduct seminars or have online programs, can handle refresher training on the basics of boiler and water heater operations.
More specific training, such as would be required to learn the details of operating and maintaining an advanced boiler-control system, is often best handled by training representatives from the manufacturer.
Managers can start the selection process by getting a list of references from the prospective vendor or provider and talking with people who actually went through the training to better understand their experiences.
For each program being evaluated, managers must consider a number of factors. If the program is held at a remote location, what are the travel costs? Can people attend different sessions, or will all operators and maintenance personnel have to attend the same sessions? How often does the provider offer the program?
If the program is to be held in the facility, what does it cost to bring in the trainers? Does the facility have the necessary space and equipment? Can managers honestly expect operators and maintenance personnel to attend the sessions without interruption or being called away for an emergency?
2. In Boilers, Retrocommissioning Can Address Energy Inefficiency
Today's tip from Building Operating Management comes from James Piper, a contributing editor for Building Operating Management and Maintenance Solutions magazines: A retrocommissioning process can identify and address areas of energy inefficiency in boilers and water heaters.
The retrocommissioning process begins with a detailed review of the boiler or water heater, including data on equipment installed, connected loads, the critical nature of the loads, maintenance history, and operating performance.
Besides installation errors, operators might have made changes to the installation over the years. Of particular interest are changes they implemented to correct maintenance issues that are preventing the unit from operating as efficiently or effectively as intended.
Next, facility managers need to review maintenance records for the boiler and consider whether technicians have performed maintenance according to manufacturer recommendations or bypassed certain features to circumvent operational issues. They also need to determine whether the boiler has required more maintenance as it has aged, and they need to identify operational and maintenance issues.
Technicians need to check and test safety features to ensure proper operation. They also must measure the boiler's efficiency under different loads and verify the boiler's control system operates properly.
Once technicians have completed the test and managers have analyzed the results, managers will be able to identify the steps operators and technicians can take that will improve efficiency and performance. These steps can range from small changes in operating procedures to large overhauls of boiler components. Managers then will be able to estimate the cost and time needed to take these steps and evaluate their options.
The results of data-gathering and testing will be a road map managers can use to improve equipment operation. It will provide a list of recommended tasks, along with relative costs. Managers can implement some steps without interfering with the boiler's operation. Others will require careful scheduling because of the needed shutdown and interruption of service.
Retrocommissioning is not necessarily a one-time task. Facility managers must be ready to repeat the process to ensure the boiler or water heater continues to operate efficiently. The timing of the process will depend on the application, as well as the condition and size of the installation.
3. How to limit contamination on cooling-tower performance
One common issue with cooling tower operation is contamination. The environment in which cooling towers operate exposes them to a range of contaminants. Inorganic solids such as dust, dirt, sand, and silt are introduced into the tower from the atmosphere and the tower's water supply. These solids collect in the tower basin, erode circulation-pump impellers, clog spray nozzles, and form scale on heat-transfer surfaces.
Another common contaminant in cooling towers are organic solids, such as leaves, grass clippings, pollen, algae, and bacteria. As with inorganic solids, organic solids tend to collect in basins, nozzles, and heat-transfer surfaces. But unlike inorganic solids, organic solids can pose a health risk to personnel.
Managers have several options for limiting the impact of contamination on cooling-tower performance. Water-treatment programs can help keep the contaminants suspended in the water, limiting their ability to form scale. Programs also can help minimize the growth of organic contaminants.
Even with a well-designed water treatment program, the quantity of solids in a cooling tower's circulating water tends to increase, so most tower manufacturers recommend a blowdown system that bleeds off a portion of the circulating water and replaces it with fresh circulating water. Technicians need to set the concentration of solids in the circulating water, as well as the rate at which water is replaced, in order to keep the tower operating within the manufacturer's guidelines for suspended solids.
To limit the accumulation of living organisms, manufacturers use two methods of water treatment — biocides in circulating water and exposing the water to ultraviolet (UV) light. Biocide programs must be designed for the specific environment in which the tower operates and be regularly monitored to be effective.
UV systems use chambers installed that expose the circulating water to a moderate level of UV light. The light is intensive enough to disrupt the DNA material within most organisms, either killing them or preventing them from reproducing.
4. HVAC Efficiency Should Be Part Of A Broad Strategy
Today's tip from Building Operating Management comes from Daniel H. Nall of Flack + Kurtz. For facility managers interested in efficiency, the HVAC system offers a significant opportunity. But the opportunity to boost HVAC efficiency should not be addressed in isolation. To be most effective, HVAC efficiency tactics should be part of a broad strategy to reduce energy use.
The pursuit of energy efficient buildings involves the integration of multiple strategies and systems. These systems include architectural enclosure, lighting, domestic water heating, vertical transportation and HVAC.
For HVAC systems, the loads come primarily from five sources: the building envelope (heating and cooling), lighting (cooling), occupancy (cooling), equipment for programmed use (cooling) and ventilation (heating and cooling).
Ventilation load is a function of either the number of persons occupying the space or of the mechanisms necessary to control contaminant concentration and introduction to the space. In most climates of the eastern and southwestern regions of the United States, minimization of outside airflow is an effective energy conservation strategy for some portion of the year, when the outside air is either warm and humid or very cold. Control of ventilation rate determined by occupancy, referred to as demand-control ventilation, is a common energy conservation strategy, especially for spaces with intermittent dense occupancy. Conventional practice would require continuous provision of the maximum calculated ventilation rate, allowing the peak occupancy to be averaged over several hours. Demand-control ventilation would provide the exact flow rate required for actual occupancy at a point, but would allow ventilation to be reduced to a minimum when the space is "in use," but unoccupied. Procedures for implementing demand-control ventilation are described in detail in ASHRAE Standard 62.1, the ventilation standard for acceptable indoor air quality.
With heating and cooling loads reduced to a minimum, utilizing a high-performance building envelope, high-performance lighting with daylight-responsive lighting controls and occupancy sensors, Energy Star office equipment and demand-controlled ventilation, the energy efficiency of the HVAC systems themselves can be addressed.
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