Evaporator Coils - Expert Commentary

Cooling Tower Cleaning And Preventive Maintenance Reduces Energy Costs
Cooling Tower Cleaning And Preventive Maintenance Reduces Energy Costs

A cooling tower allows building owners and operators to take advantage of low cooling water temperatures and higher rates of heat rejection per square meter inherent in evaporative cooling systems. A well maintained cooling tower enables cooling systems to perform at optimum efficiency, reliably and cost-effectively, with contractors who maintain cooling systems able to service their customers with comprehensive and routine cooling tower maintenance programs that should maintain cooling performance for many years. Humble cooling tower Unfortunately, the humble cooling tower is often the forgotten component of the water cooling system when it comes to maintenance, but extremely high up the table when it comes to safety, so while certain tasks are regularly carried out others can be overlooked. A well maintained cooling tower should be able to reliably deliver its design fluid temperature A well maintained cooling tower should be able to reliably deliver its design fluid temperature and flow rate relative to the ambient condition indefinitely, but since its heat transfer operation creates a natural ‘air-scrubber’ environment, removing impurities from the cooling air as well as the circulating water, the cooling tower needs regular routine inspections and maintenance to continue performing at its best, and a small deterioration in performance should be expected, but easily managed. Cooling towers use large volumes of ambient air to take heat away from a process through sensible and non-sensible cooling. Critical maintenance activities Non-sensible cooling is a term that describes heat rejection through evaporation, where air will gain moisture until it reaches saturation, which is when the air is fully laden with water at 100% RH. This increase in water content requires energy to occur and this is obtained by taking heat out of the circulating water, reducing the temperature of the water in the process. Sensible cooling also occurs, which is where the colder inlet air reduces the temperature of the water due the difference in the air and water temperature, and in turn heats up as it travels through the heat exchange media. Because of this, one of the most critical maintenance activities of cooling systems is to ensure that the heat transfer has the best conditions to occur. Air moving equipment Maintenance on the air moving equipment will focus on the condition of the fans themselves The best conditions mean that the airflow is optimal, the heat exchange surfaces are clean and correctly installed, and the water distribution is balanced and operating correctly. Unless it is a natural draft cooling tower, the airflow will be created by fans which are driven by motors that are either directly attached to the fans or operate through gearboxes or fan belts. Maintenance on the air moving equipment will focus on the condition of the fans themselves, ensuring that the blade angles are set to achieve the necessary airflow if they can be adjusted and that the gearboxes or belts are operating properly with sufficient lubrication in bearings and gearboxes. Heat exchange media The heat exchange media in the cooling tower should be selected to offer the best trade-off between the tendency to foul and the amount of heat exchange surface. Maintenance on these components focuses first on the cleanliness of the heat exchange surfaces, as well as ensuring that the correct type of heat exchange media is being used and that it is properly fitted. The distribution systems in cooling towers are also essential to efficient operation Incorrect fill type or poor installation can lead to the packs becoming blocked quickly or could result in higher pressure drops reducing airflow. Poorly fitted fill packs can lead to air bypassing the water through gaps in the fill pack and results in loss of thermal performance and higher drift rates. The distribution systems in cooling towers are also essential to efficient operation. Heat exchange surfaces Heat exchange surfaces are only effective if there is a steady flow of water over them, blocked or broken nozzles can lead to an imbalance of water flow which results in variations of wetting rates or even dry spots throughout the fill where the airflow will be less effective. Water flow, airflow and heat exchange surface are the essential ingredients in cooling tower thermal performance, but these three critical subsystems don’t make up the entire system. The remaining systems are related to safety, access and containment, which carry a significant importance when concerned with the safe and effective operation of a cooling tower. Preventing direct sunlight Cooling towers are ultimately maintainable through a series of interconnected subsystems These systems include drift eliminators that prevent harmful water droplets from leaving the cooling tower, air inlet honeycombs that prevent direct sunlight from entering the cooling tower and reduce airside contamination, access systems that allow safe access for maintenance and the general fabric of tower to provide containment of fluids and protection to operators. All these things should be considered in a comprehensive maintenance plan which goes beyond cleanliness to ensure that you have not only a safe system but a high performing system. Cooling towers are ultimately maintainable through a series of interconnected subsystems that can all be relatively easily and cost effectively replaced. By allowing correctly maintained systems to operate at peak efficiency, they will work safely for many years.

HVAC Maintenance Vital As Businesses Reopen Post COVID-19
HVAC Maintenance Vital As Businesses Reopen Post COVID-19

In what can only be described as a very turbulent year, many businesses have had to shut their doors and have all but forgotten about the general upkeep of their sites. With priorities shifted to keeping companies afloat and staff employed, maintenance and servicing has taken a backseat, and many systems will be deteriorating unnoticed. It goes without saying that one of the first tasks that employers will have to tackle when returning to work is a deep clean. As we are still in the throes of a pandemic, a clean and disinfected workplace is the number one priority that needs to be ensured, before any staff can be welcomed back to work. This should be closely followed by maintenance of the site’s equipment. Importance of regular HVAC maintenance Regular HVAC maintenance is extremely important as it keeps systems performing efficiently and effectively Regular HVAC maintenance is extremely important as it keeps systems performing efficiently and effectively. The nature of HVAC maintenance does change depending on the time of year, and with some sites being shut for months and through different seasons, managers will need to review their current equipment to ensure it is compliant and working correctly as soon as possible as signs of normality start returning and facilities begin to reopen. While warehouses and factories may have still been operating in some capacity over the last 12 months, many office buildings have seen little to no employees for more than a year in some cases, therefore, risking deterioration and even damage to their systems going unnoticed and untreated. But with so many pieces of equipment at each site, it is often hard to know where to start and what to prioritize. Following HVAC manufacturer’s recommendations In order for businesses to keep functioning as best as they can and to avoid any more disruption, those in charge of maintenance and servicing need to be educated on how the conditions of a system affects the type of work it needs. Manufacturer’s recommendations should also be taken into account. To help define what these are and how to approach them, mechanical and electrical engineers recommend: The coils and pipes in HVAC equipment that are responsible for heat transfer are checked regularly, because if the equipment gets dirty, it won’t transfer heat and energy as well. Checking controls annually to ensure that the HVAC system is running properly, as control calibration can alter. By scheduling regular check-ups, accurate operation is maintained. Maintaining equipment with fans quarterly to maximize longevity. Three key areas include monitoring the impellers, belts and bearings for any dirt, wear and tear, friction or erosion. Keeping an eye on filters, as when they are clogged, it increases the pressure drop in a system, which makes fans work harder to maintain the same airflow. A quarterly clean is usually sufficient for most filters. This is also true of strainers in systems. Optimizing HVAC and electrical equipment With spring now upon us, businesses need to optimize their HVAC and electrical equipment for maximum efficiency With spring now upon us, businesses need to optimize their HVAC and electrical equipment for maximum efficiency. This includes reviewing the sequence of operations for a morning warm up and cool down. However, it’s important to remember that because of prolonged closures over the last 12 months, autumn and winter checks, and in some cases, even summer checks were not able to be carried out in 2020, so before the spring work begins, backdating the maintenance is a good place to start. Ensuring buildings’ energy efficiency With the help of experts, HVAC maintenance doesn’t have to be time-consuming and overwhelming, but it’s a critical part of maintaining an energy-efficient building that is both comfortable and reliable. With regular servicing and some basic knowledge of what is required, sites can maintain optimum efficiency all year round. Noise complaints can also be an issue, if HVAC maintenance isn’t carried out regularly. Spring is a good time for businesses to perform services on their equipment, prior to the summer months starting and should be used to ensure that condenser coils and air handler filters are both clean. The dirtier the equipment, the noisier and less efficient it becomes, which is bad news for any business. Preparing buildings for staff returning to work When a building is returning to normal occupancy after a lengthy closure, additional checks must be considered before reopening is discussed. When a building is initially mothballed, it must be prepared for long term vacancy, but many businesses will not have had this opportunity before the national lockdown, which basically entails that these checks will not have been carried out. After a building becomes unoccupied, it is not the case that maintenance activity should also stop After a building becomes unoccupied, it is not the case that maintenance activity should also stop. At the very least, the frequency of existing planned maintenance will change, but in some cases, more maintenance tasks are required in order to keep the site ticking over. This includes flushing of water systems, Legionella testing and insurance inspections to keep the property functional and compliant. Countering health and safety issues  As the COVID-19 lockdown restrictions are lifted across the United Kingdom and many businesses are gradually reopening, it will present health and safety problems that have not been faced before and will very likely see a surge in services and maintenance being required. With this in mind, it is vital that maintenance becomes a priority as normal service is resumed to not only ensure efficiency, but also to make sure that no employee or visitor to a site is put in danger. Emerging from a surreal 12 months, there is no doubt that companies will still face challenges, so it is crucial that avoidable maintenance problems do not become one of them, so don’t delay in booking routine checks.  

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