Here are the Top 10 HVAC Service Calls, along with their typical solutions and estimated costs. Most of these problems occur due to poor installation, inadequate service procedures, or lack of maintenance.
#1 No Cool Air Flowing
Problem: Dirty air filters or blocked vents.
Solution: Replace air filters and clear any obstructions. Clogged and dirty filters restrict airflow and significantly decrease the system’s efficiency. When airflow is obstructed, air can bypass the filter, depositing dirt directly onto the evaporator coil, which impairs the coil’s ability to absorb heat. By replacing a dirty, clogged filter with a clean one, you can reduce your air conditioner’s energy consumption by 5% to 15%. Dirty filters also put additional stress on the indoor fan leading to fan failure.
Estimated Cost: $70 to $200
#2 Thermostat Issues
Problem: Malfunctioning or incorrectly set thermostat.
Solution: Calibrate, repair, or replace the thermostat. Approximately 25% of U.S. households use a smart thermostat. Smart thermostats are designed to be user friendly and energy efficient but can be incorrectly programmed. Issues can be related to thermostat complexity, user error, default settings, connectivity issues or lack of training.
Estimated Cost: $90 to $300
#3 Refrigerant Leaks
Problem: Low refrigerant due to leaks or improper initial charge.
Solution: Locate and repair leaks, recharge refrigerant. Inexperienced technicians can under or overcharge system with refrigerant. Make sure refrigerant charge matches the manufacturers recommendations, and don’t add refrigerant until system has been tested for leaks.
Estimated Cost: $200 to $1,500
#4 Poor Airflow
Problem: Blocked ducts, vents or dirty filters, or fan issues.
Solution: Clear blocked ducts, unblock vents, clean coil, repair or replace the fan motor.
Estimated Cost: $300 to $900
#5 Strange Noises
Problem: Loose or damaged parts, debris in the system.
Solution: Inspect and tighten components, remove debris, and replace damaged parts. Some reasons for noises can be worn bearings in the fan motor or the compressor can wear out over time, causing grinding or squealing noises. If your system has belts, worn or misaligned belts can cause squealing or screeching noises. Loose bolts, screws, or panels within the unit can vibrate and produce rattling noises.
Estimated Cost: $100 to $400
#6 AC Unit Won’t Turn On
Problem: Electrical issues, tripped breaker, faulty capacitor, or burned-out compressor.
Solution: Check and reset breaker, replace capacitor, inspect wiring, or hit the reset button located in compressor’s access panel if available. On hot days it’s not uncommon for the high-pressure limit switch to shut the system off to protect the compressor or draw excessive amps that cause the breaker to trip. Compressors can burn-out due to many issues such as electrical spikes or inconsistent voltage levels, faulty wiring or components, low refrigerant charge or contaminated refrigerant, operating in extreme weather, normal wear and tear.
Estimated Cost Electrical Issues: $100 to $350
Estimated Cost burned-out Compressor: $1,500 to $2,500 or more depending on type and size of compressor.
Solution: Unclog drain line, thaw coils, ensure proper insulation. A clogged drain line could also reduce the unit’s capacity to reduce humidity levels.
Estimated Cost: $150 to $500
#8 Unpleasant Odors
Problem: Mold or mildew in the ductwork or unit.
Solution: Clean ducts, replace filters, clean drain pan, and check for mold. Cleaning ducts enhances HVAC system efficiency by improving airflow and reducing energy consumption. It helps reduce odors by removing dust, mold, and pest residues. Additionally, it significantly improves indoor air quality by reducing allergens, mold spores, and other pollutants, contributing to better respiratory health and overall well-being for the occupants. Regular duct cleaning is a crucial part of maintaining a healthy, efficient, and comfortable indoor environment.
Estimated Cost: $300 to $700
#9 Frequent Cycling
Problem: Thermostat issues, dirty filters, improper refrigerant levels, oversized air conditioner. Oversized air conditioners can cause the system to cycle on and off frequently, a phenomenon known as short cycling which causes rapid cooling, inadequate dehumidification, increased wear and tear, higher energy bills, and temperature fluctuations.
Problem: Inefficient system, dirty coils and bent fins.
Solution: Clean coils and comb any bent fins. Dirty coils and bent fins can cause various issues such as reduced cooling efficiency, higher energy consumption, and potential system freeze-ups. The typical solution involves cleaning the coils, where the cost will depend on the severity and accessibility of the coils. Regular maintenance to keep the coils clean can prevent many related problems and ensure the system operates efficiently.
Estimated Cost: $150 to $500
These costs are approximate and can vary based on location, the specific HVAC system, and the service company rates. Regular maintenance can help prevent many of these issues and extend the lifespan of the HVAC system. Let us know in the comments below what your top 3 service call complaints are, and the typical cost to repair.
Top 10 HVAC Service Calls and their Cost to Repair
When buying a car, you might look at how many miles per gallon the car can achieve when comparing which car is more efficient. This is an indication of its ability to convert fuel into a certain distance traveled. A similar ratio in the HVAC industry is used to indicate how efficient an air conditioner or heat pump is at using electricity to produce BTU’s.
Beginning on January 1, 2023, the US Department of Energy (DOE) has changed to a new rating system where different regions of the United States are divided up. There are now Northern and Southern regions with varying efficiency ratios. Any air conditioners installed starting in 2023 and after in the Southwest and Southeast regions of the United States must meet the new SEER2 energy efficiency standard.
SEER2 Energy Efficiency Standards Map
Regions matter because different standards are based on the climate needs of customers living in the North, Southeast, and Southwest regions. People in southern climates, where air conditioners are used more frequently, require more energy-efficient systems. Therefore, depending on your geographical region and HVAC needs, split system air conditioners, heat pumps, and single-package systems may have varying efficiency standards.
Energy Efficiency Ratio (EER)
The Energy Efficiency Ratio (EER) measures the efficiency of an air conditioning system or heat pump. It indicates how effectively the unit converts electrical energy into cooling output. Specifically, EER represents the ratio of the cooling capacity (in British Thermal Units per hour, or BTU/h) to the power input (in watts) at a given operating condition.
EER Calculation
EER = Cooling Capacity (BTU/h) / Power Input (W)
EER is typically measured under specific conditions: an outdoor temperature of 95°F, an indoor temperature of 80°F, and 50% relative humidity. This standardization allows for a direct comparison of different units under the same conditions.
Seasonal Energy Efficiency Ratio (SEER)
The Seasonal Energy Efficiency Ratio (SEER) measures the overall energy efficiency of an air conditioning system or heat pump over an entire cooling season. Unlike the Energy Efficiency Ratio (EER), which is calculated at a single operating condition, SEE considers the variations in temperature and cooling demand that occur throughout the season. It represents the ratio of the total cooling output (in BTUs) to the total electrical energy input (in watt-hours) over the cooling season.
SEER Calculation
SEER = Total Cooling output over a Season (BTU) / Total Electric Energy Input over a Season (Wh)
SEER ratings provide a standardized way to compare the energy efficiency of different air conditioning units and heat pumps, considering the varying cooling demands throughout the cooling season. This helps consumers and professionals make informed decisions when selecting HVAC equipment for energy efficiency and cost savings.
Heating Seasonal Performance Factor (HSPF)
The Heating Seasonal Performance Factor (HSPF) measures the efficiency of heat pumps in heating mode over an entire heating season. It represents the ratio of the total heating output (in British Thermal Units, or BTUs) to the total electrical energy input (in watt-hours) during the heating season. HSPF provides an indication of how efficiently a heat pump converts electricity into heat over a range of conditions and temperatures experienced throughout the heating season.
HSPF Calculation
HSPF = Total Heating Output (BTU) / Total Electric Energy Input (Wh)
HSPF provides a comprehensive measure of a heat pump’s heating efficiency over a typical heating season, helping consumers and professionals make informed decisions about equipment that offers better energy savings and performance in various climates.
The new SEER2 Standards
The calculation for SEER2, like the original SEER, is designed to measure the overall energy efficiency of an air conditioning system or heat pump over a cooling season. While the fundamental formula remains similar, SEER2 incorporates updated testing conditions and procedures to better reflect real-world performance.
SEER2 Calculation
SEER2 = Total Cooling Output (BTU) / Total Electric Energy Input (Wh)
Key Differences in SEER2 vs SEER Calculation:
1. Updated Testing Conditions
SEER2 includes more representative testing conditions that reflect a wider range of operating environments and load profiles, considering part-load and variable load conditions more accurately.
2. Improved Measurement Techniques
SEER2 employs updated measurement techniques to account for variations in system performance, cycling losses, and other factors that impact efficiency under real-world conditions.
3. Standardized Load Profiles
SEER2 uses standardized load profiles that mimic the fluctuating cooling demands typical of an entire cooling season, offering a more comprehensive assessment of system efficiency.
Example Calculation
If an air conditioning system provides 60,000 BTUs of cooling over a season and consumes 4,000 watt-hours (Wh) of electricity during that time, the SEER2 would be calculated as follows:
SEER2 = 60,000 BTU / 4,000 = 15
Application
Regulatory Standards: SEER2 is used to set minimum energy efficiency standards for new HVAC systems, ensuring they meet contemporary performance requirements.
Product Comparison: Consumers and professionals can use SEER2 ratings to compare the efficiency of different air conditioning units and heat pumps, aiding in the selection of more energy-efficient models.
Energy Savings: Higher SEER2 ratings indicate better energy efficiency, which translates to lower energy consumption and cost savings over the cooling season.
By incorporating more realistic testing conditions, SEER2 provides a more accurate measure of an HVAC system’s seasonal energy efficiency, helping to promote the use of systems that are more efficient and environmentally friendly.
Uses of EER, SEER and HSPF
Performance Assessment: These calculations offer a standardized way to compare the efficiency of different air conditioners or heat pumps. A higher value indicates better energy efficiency.
Energy Cost Savings: HVAC Equipment with higher ratings use less electricity to produce the same amount of heating or cooling, leading to lower energy bills.
Environmental Impact: More efficient air conditioners or heat pumps reduce overall energy consumption and greenhouse gas emissions, contributing to environmental sustainability.
Regulatory Compliance: In many regions, building codes and energy standards specify minimum efficiency ratio requirements for air conditioners and heat pumps. Compliance with these regulations ensures that installations meet energy efficiency standards.
In this article we’ll cover how to calculate cubic yards of excavation and backfill, soil types, excavation equipment, soil testing, compaction, swell factor, the difference between excavating and trenching, and when shoring or trench supports are required.
First let’s cover a few very important items that need to be done before any digging begins.
If you prefer to watch the video of this presentation, then scroll to the bottom.
Call 811 before Digging
The first thing to do is call 811. Calling 811 before digging is crucial because it helps identify and locate underground utilities such as gas lines, water pipes, and electrical cables. This free service coordinates with utility companies to mark the locations of these buried lines, preventing accidental damage that can cause service disruptions, costly repairs, and serious safety hazards such as gas leaks or electrical shocks.
Call 811 before any digging begins to get notified of any known underground utilities.
By calling 811, individuals and contractors ensure compliance with safety regulations and protect themselves, their property, and the community from potential dangers associated with unmarked utilities.
APWA Color Coding
Using the American Public Works Association (APWA) color coding system to mark your site before excavating ensures clear and standardized communication of underground utility locations. This system assigns specific colors to different types of utilities, such as red for electric power lines, yellow for gas, oil, or steam, and blue for potable water.
American Public Works Association color chart for marking excavations
By using these color codes, you help prevent utility damage, reduce the risk of accidents, and comply with industry best practices and regulations, ensuring a safer and more efficient excavation process. A white mark is used to outline the proposed route of the excavation. These markings can be on the surface or with flags and stakes used to increase visibility.
Tolerance Zone
The tolerance zone is a safety buffer zone around existing underground utilities within which excavation must be conducted with extra caution. Typically, it extends 18 to 24 inches (45 to 60 centimeters) from each side of a marked utility line. Within this zone, hand digging or using non-invasive methods like vacuum excavation is required to avoid damaging the utilities. Adhering to the tolerance zone helps prevent utility strikes, ensuring the safety of workers and the integrity of underground infrastructure.
Tolerance Zone when excavating near existing utilities
One of the first steps is to determine the Soil type.
Soil Classifications
OSHA (Occupational Safety and Health Administration) classifies soils into three main categories—Type A, B, and C—based on their stability and cohesiveness, which is critical for ensuring safety during excavation work. The soil type must be identified by a competent person as defined by OSHA. Here are the definitions and purposes of these classifications:
Soil Types and their Sloping Requirements per OSHA
Type A Soil
Type A soil is the most stable and cohesive type of soil. It includes clay, silty clay, and hardpan, with an unconfined compressive strength of 1.5 tons per square foot (tsf) or greater.
Knowing that Type A soil is highly stable helps in planning safe excavation slopes and support systems, minimizing the risk of cave-ins.
Type B Soil
Type B soil has medium stability. It includes silt, silt loam, sandy loam, and previously disturbed soils, with an unconfined compressive strength greater than 0.5 but less than 1.5 tons per square foot.
Understanding that Type B soil is less stable than Type A guides the implementation of additional safety measures such as shoring or sloping at a less steep angle.
Type C Soil
Type C soil is the least stable type. It includes gravel, sand, and loamy sand, with an unconfined compressive strength of 0.5 tons per square foot or less. It also includes submerged soil or soil from which water is freely seeping.
Recognizing Type C soil’s high risk of collapse necessitates the use of the most stringent protective systems, like benching, shoring, or shielding, and sloping the excavation walls at the shallowest angles.
These classifications help ensure that appropriate excavation practices and protective systems are used to maintain worker safety and prevent cave-ins. You can also test the soil.
How to Protect Workers from Cave-ins
Safety is the main concern when working around excavations. There are various protective systems to safeguard workers from cave-ins during excavation and trenching operations. These protective systems are designed to provide support and stability to the excavation walls, reducing the risk of collapse and ensuring worker safety. The primary types of protective systems include:
Sloping
Sloping involves cutting back the trench walls at an angle to create a stable slope that reduces the risk of collapse. The angle of the slope depends on factors such as soil type, excavation depth, and environmental conditions.
Using the Excavation calculator found in the MEP Academy Plumbing Estimating Spreadsheet you can easily calculate the required cubic yards required. Just enter the soil type along with the length, width and depth of the excavation or trench. The calculator takes into consideration the slope if indicated. Just put an “X” in the box for Stable Rock which doesn’t require a slope, or type A soil which is a 3/4:1 slope, type “B” at 1:1, and type “C” soil for 1-1/2:1. The total cubic yards are automatically calculated including any sloped area.
Soil Excavation Calculator in the MEPAcademy’s Plumbing Estimating Spreadsheet
To get a copy of the Estimating Spreadsheet with the Excavation and backfill calculator follow this link. Plumbing Estimating Spreadsheet.
Benching
Single and multiple benching are techniques used to create safe slopes in excavations, particularly in trenches and other large soil removals. These methods help prevent soil collapse and ensure worker safety by reducing the risk of cave-ins. Here’s a description of each:
Bench Excavations
Single Bench
A singe bench involves excavating the soil to create one horizontal step or bench along the slope of the excavation. This bench provides a stable working platform and reduces the steepness of the slope, which helps prevent soil from sliding into the trench.
Single benching is typically used in less deep excavations where the height of the slope does not require multiple steps for stability. It’s suitable for soils that are relatively cohesive and stable.
Multiple Bench
A multiple bench cut involves creating a series of horizontal steps or benches at regular intervals along the slope of the excavation. Each bench acts as a break in the slope, significantly reducing the likelihood of a cave-in by supporting the soil above it.
Multiple benching is used in deeper excavations where a single bench would not provide sufficient stability. It is especially important in less cohesive soils that are more prone to collapse. This method ensures greater safety by distributing the weight of the soil and providing additional support.
Key Considerations
As a general rule, the bottom vertical height of the trench must not exceed 4 ft (1.2 m) for the first bench. Subsequent benches may have a vertical height of up to 5 ft (1.5 m) in Type A soil and 4 ft (1.2 m) in Type B soil, reaching a total trench depth of 20 ft (6.0 m).
Slopes vs Trenches
To avoid the need for a sloped excavation, which can be impractical in certain situations due to space constraints or other factors, several alternative protective systems can be used to ensure worker safety and prevent cave-ins. Trenches 5 feet (1.5 meters) deep or greater require a protective system unless the excavation is made entirely in stable rock. If less than 5 feet deep, a competent person may determine that a protective system is not required. The alternatives to sloping include these trench options:
1. Shoring Systems:
Hydraulic Shoring: Uses hydraulic pistons to apply pressure to trench walls, holding them in place. It’s adjustable and can be quickly installed and removed.
Mechanical Shoring: Involves using metal supports such as screw jacks, struts, and beams to brace trench walls. These systems are strong and can be tailored to the specific dimensions of the trench.
Pneumatic Shoring: Similar to hydraulic shoring but uses air pressure to stabilize the trench walls.
2. Trench Boxes
Trench boxes are robust steel or aluminum structures placed inside the trench to protect workers from cave-ins. They provide a safe working area within the trench and are particularly useful for deep or narrow trenches.
Trench boxes come in various sizes and configurations to suit different excavation needs and can be stacked for deeper excavations.
3. Shield Systems:
Shield systems are portable, protective structures that can be moved along the trench as work progresses. They can be made of steel, aluminum, or composite materials and offer flexibility in terms of size and strength.
Examples include slide rail systems, which provide support to the trench walls as the excavation proceeds.
We have shown you three protective system and there are many others available.
Using these protective systems allows for vertical or near-vertical trench walls, which can be critical in areas with limited space or where traditional sloping is not feasible. The choice of system depends on factors such as soil conditions, trench depth, available space, and project-specific requirements. Each method provides a safe working environment for workers and ensures compliance with OSHA regulations and industry safety standards.
When is Shoring Required
Shoring is required during excavation or trenching when the soil’s stability is compromised, posing a risk of collapse or cave-in. Here are common scenarios when shoring is necessary:
Unstable Soil Conditions
Shoring is essential when excavating in soil types prone to collapse, such as loose or granular soils (Type C soils according to OSHA classification). These soils lack cohesion and are at a higher risk of cave-ins without support.
Deep Excavations
As the depth of the excavation increases, the lateral pressure exerted by the surrounding soil also increases. Shoring becomes necessary to prevent the walls of the trench from collapsing inward under the pressure, ensuring the safety of workers.
Adjacent Structures
When excavating near existing structures, utilities, or roads, shoring may be required to prevent soil movement that could damage adjacent infrastructure. Shoring also provides stability to the excavation site, minimizing the risk of ground settlement or subsidence.
Water Table
Excavations conducted below the groundwater table are susceptible to water seepage and soil instability. Shoring is necessary to prevent water infiltration and maintain the integrity of the excavation walls, especially in cohesive soils that may become saturated and lose strength.
Changing Soil Conditions
Soil conditions can change unexpectedly during excavation due to weather conditions, groundwater fluctuations, or disturbances from nearby activities. If soil stability becomes compromised, shoring may be required to ensure the safety of workers and prevent accidents.
Regulatory Requirements
Local regulations and safety standards may dictate when shoring is required based on factors such as excavation depth, soil type, and proximity to existing structures or utilities. Compliance with these regulations is essential to ensure safe excavation practices.
In summary, shoring is necessary during excavation or trenching operations to provide support and stability to the excavation walls, reducing the risk of collapse and ensuring the safety of workers and surrounding infrastructure.
Soil Compaction
Compaction refers to the process of densifying the soil or backfill material to increase its load-bearing capacity and prevent settling or shifting over time. After plumbing pipes or structures are placed in the excavated trenches, the backfill material is added in layers and each layer is compacted using mechanical means such as vibratory plate compactors, rollers, or tampers. Proper compaction ensures that the soil is stable and that voids are minimized, which helps to protect the integrity of the plumbing infrastructure, preventing future issues such as pipe displacement or leaks due to ground movement.
Swell Factor
Swell refers to the increase in volume that soil or excavated material undergoes when it is disturbed and removed from its natural, compacted state. When soil is excavated, it expands because the tightly packed particles are loosened, resulting in an increase in volume. This phenomenon is known as swell.
Soil Swell Factors. When soil increases in size after excavation.
Understanding swell is important for plumbers and construction professionals because it affects the amount of backfill material that will be required to refill an excavated trench or hole. Proper planning for swell ensures that there is sufficient material to achieve the desired compaction and stability when backfilling around plumbing installations.
Sand and Gravel Bedding
Using sand and gravel at the bottom of an excavation where piping is being installed serves several important purposes:
Providing a Stable Bedding:
Sand and gravel create a stable and even bedding for the pipes, ensuring that they are well-supported along their length. This reduces the risk of pipe deflection or damage due to uneven settlement or point loading.
Facilitating Drainage:
Sand and gravel promote good drainage around the pipes, preventing water accumulation that could lead to soil instability or erosion. Proper drainage helps maintain the integrity of the piping system and prevents issues related to waterlogging or frost heave.
Protecting Pipes from Sharp Objects:
Sand and gravel act as a cushion, protecting the pipes from sharp rocks or other debris in the soil that could puncture or damage them. This is particularly important for plastic or PVC pipes, which are more susceptible to damage from sharp objects.
Easing Piping Installation:
The granular nature of sand and gravel makes it easier to achieve precise grading and alignment of the pipes during installation. This ensures that the pipes are laid at the correct slope and elevation for optimal performance.
Amount of Sand and Gravel Used
The amount of sand and gravel used at the bottom of an excavation varies depending on the type and size of the piping, as well as the project specifications. However, typical guidelines include:
Bedding Layer:
A bedding layer of sand or gravel is usually placed 4 to 6 inches (10 to 15 centimeters) thick. This layer provides a firm foundation for the pipes.
Initial Backfill:
After the pipes are laid, an initial backfill of sand or gravel is placed around and over the pipes to a depth of about 6 to 12 inches (15 to 30 centimeters) above the pipe. This initial backfill helps to secure the pipes in place and provides additional protection.
Final Backfill:
The final backfill, which may consist of the excavated soil or other suitable material, is then placed on top of the initial backfill. The final backfill is typically compacted in layers to prevent settling and ensure stability.
These layers help ensure that the pipes are properly supported, protected, and aligned, contributing to the longevity and functionality of the piping system. The exact specifications may vary based on local codes, engineering requirements, and the specific conditions of the project site.
Digging Equipment used for Excavations and Trenches
Excavations and trenches require specialized equipment to efficiently and safely remove soil and create the desired shapes and depths. Here are various types of digging equipment commonly used for these purposes:
Excavators
Excavators are versatile machines equipped with a bucket attached to a hydraulic arm. They can rotate 360 degrees and are capable of digging, lifting, and loading materials.
Excavators are suitable for a wide range of excavation tasks, including digging trenches, foundations, and utility trenches.
Backhoe Loaders
Backhoe loaders combine a backhoe (rear-mounted digging arm) with a loader (front-mounted scoop). They are versatile and commonly used in construction projects.
Backhoe loaders are useful for smaller excavation jobs, such as digging trenches for utilities, backfilling, and loading materials.
Trenchers
Trenchers are specialized machines designed specifically for digging narrow and deep trenches. They feature a rotating chain or blade that cuts into the ground to create the trench.
Trenchers are ideal for excavating trenches for utilities like water pipes, sewer lines, and electrical conduits.
Mini Excavators
Mini excavators are compact versions of standard excavators, with a smaller footprint and reduced weight. They offer increased maneuverability and are suitable for tight spaces.
Mini excavators are commonly used for small-scale excavation projects, landscaping, and utility installation in urban areas or confined spaces.
Crawler Excavators
Crawler excavators are equipped with tracks for stability and mobility over rough terrain. They offer high digging power and are suitable for heavy-duty excavation work.
Crawler excavators are used in large-scale excavation projects, such as road construction, mining, and earthmoving.
Skid Steer Loaders
Skid steer loaders are compact, maneuverable machines with a small turning radius. They feature a bucket or attachment mounted on a pivoting frame.
Skid steer loaders are versatile and can be used for various tasks, including excavation, loading, grading, and landscaping.
These are just a few examples of the equipment used for excavations and trenches. The choice of equipment depends on factors such as the size of the project, the type of soil, accessibility, and the specific requirements of the task at hand.
We’ll discuss an adiabatic fluid cooler, an air-cooled condenser with water spray, and an air-cooled condenser using adiabatic cooling.
Air-Cooled Condenser with Water Spray and Adiabatic Fluid Coolers
An adiabatic fluid cooler is a device used for cooling fluids, typically water or a water-glycol mixture, while an adiabatic air-cooled condenser is used to cool a refrigerant based systems. These systems are used in industrial and commercial applications. They operate based on the principle of evaporative cooling combined with a heat exchanger.
If you prefer to watch the video of this presentation, then scroll to the bottom.
How Adiabatic Cooling Works:
The hot water in an adiabatic fluid cooler flows into the heat exchanger. The heat exchanger consists of coils of tubes surrounded by fins. These tubes are in contact with the hot water. As the hot water flows through them, heat is transferred to the coil surface and fins of the heat exchanger. The heat exchanger can be provided with an epoxy coating to increase corrosion resistance without sacrificing unit capacity.
Adiabatic Fluid Cooler
Water is sprayed or circulated over a pre-cooling pad, to keep it fully wet. This fully wetted medium sits in front of the heat exchanger, and is often made of corrugated cellulose, synthetic material, or fibrous pad. Cool, dry ambient air is drawn through the wetted medium by a fan located on top of the unit, the air becomes humidified as some of the water evaporates into the air, absorbing heat from the surrounding air in the process.
The evaporation of water from the wetted medium extracts heat from the surrounding air, reducing the ambient dry bulb temperature within proximity to the wet bulb temperature. This cooled air then passes over the surface of the heat exchanger where it absorbs heat from the hot fluid inside the tubes and on the surface of the fins. The heat is then discharged to the atmosphere by fans sitting at the top of the unit. As a result, the hot fluid inside the tubes loses heat to the cooled air through the heat exchanger.
The cooled fluid exits the adiabatic fluid cooler and can be recirculated back into the system it’s cooling, such as an HVAC system or industrial process. This effectively transfers the absorbed heat to the adiabatic fluid cooler and then to the atmosphere.
Variable Speed Fans
The variable speed fans inside the adiabatic fluid cooler draws air through the wetted medium and across the heat exchanger to facilitate the cooling process. The speed of the fan(s) can be adjusted to control the cooling capacity of the unit.
By combining evaporative cooling with a traditional heat exchanger, adiabatic fluid coolers can achieve significant energy savings compared to conventional air-cooled heat exchangers, especially in hot and dry climates where evaporative cooling is particularly effective.
Reduces Water Consumption
The Adiabatic fluid cooler can eliminate or significantly reduce water consumption compared to the traditional evaporative systems. They can be operated without water until ambient conditions require additional capacity to meet demand. This reduces water consumption and the cost to treat and dispose of water. There is no water basin to hold water or that can gather dirt and debris. This is because the water passes through once and isn’t recirculated so there is no need for a recirculation pump.
Adiabatic Condenser
The adiabatic version of the air-cooled condenser uses a fully wetted medium that sits in front of the heat exchanger coil. The air flow and heat transfer process is the same as previously discussed using the adiabatic fluid cooler for water, except now it’s refrigerant as the medium.
Air-Cooled Condenser with Water Spray
For the air-cooled condenser, the refrigerant vapor enters the condenser and leaves as high-side refrigerant liquid. The system will turn on the water spray when it fails to maintain the refrigerant condensing pressure.
Refrigerant Condenser Cooled by a Water Spray System
The water is sprayed outward away from the coil into the air stream. The air is pulled across the coil by the variable speed fans. The heat from the hot refrigerant is transferred to this cooler air causing the refrigerant to condense into liquid. The condenser will conserve water by running dry and only spraying water when ambient conditions require a lower entering temperature. That’s why these systems are recommended for high ambient dry bulb climates or high temperature applications.
What is adiabatic Cooling?
Adiabatic fluid coolers or condensers operate like dry cooling systems, except they have water running over pre-cooling pads. The air is drawn through the pads depressing the ambient dry bulb temperature of the incoming air. The depressed or reduced dry bulb temperature provides for greater system heat rejection than a dry system.
