Swamp Cooler Calculator – Loan calculator

Swamp Cooler Sizing & Cost Calculator

Room Length (feet):

Room Width (feet):

Room Height (feet):

Desired Air Changes Per Hour (ACH):

Outdoor Dry Bulb Temperature (°F):

Outdoor Relative Humidity (%):

Cooler Saturation Efficiency (%):

Cooler Power Consumption (Watts):

Electricity Cost ($/kWh):

Water Cost ($/gallon):

Daily Operating Hours (hours):

function calculateSwampCooler() { var roomLength = parseFloat(document.getElementById('roomLength').value); var roomWidth = parseFloat(document.getElementById('roomWidth').value); var roomHeight = parseFloat(document.getElementById('roomHeight').value); var desiredACH = parseFloat(document.getElementById('desiredACH').value); var outdoorDryBulbTemp = parseFloat(document.getElementById('outdoorDryBulbTemp').value); var outdoorRelativeHumidity = parseFloat(document.getElementById('outdoorRelativeHumidity').value); var coolerEfficiency = parseFloat(document.getElementById('coolerEfficiency').value); var coolerPowerConsumption = parseFloat(document.getElementById('coolerPowerConsumption').value); var electricityCost = parseFloat(document.getElementById('electricityCost').value); var waterCost = parseFloat(document.getElementById('waterCost').value); var dailyOperatingHours = parseFloat(document.getElementById('dailyOperatingHours').value); // Validate inputs if (isNaN(roomLength) || isNaN(roomWidth) || isNaN(roomHeight) || isNaN(desiredACH) || isNaN(outdoorDryBulbTemp) || isNaN(outdoorRelativeHumidity) || isNaN(coolerEfficiency) || isNaN(coolerPowerConsumption) || isNaN(electricityCost) || isNaN(waterCost) || isNaN(dailyOperatingHours) || roomLength <= 0 || roomWidth <= 0 || roomHeight <= 0 || desiredACH <= 0 || outdoorDryBulbTemp < 0 || outdoorRelativeHumidity 100 || coolerEfficiency 100 || coolerPowerConsumption <= 0 || electricityCost < 0 || waterCost < 0 || dailyOperatingHours <= 0) { document.getElementById('swampCoolerResult').innerHTML = 'Please enter valid positive numbers for all fields.'; return; } // 1. Room Volume var roomVolume = roomLength * roomWidth * roomHeight; // 2. Recommended Cooler CFM // CFM = (Room Volume * ACH) / 60 minutes var recommendedCFM = (roomVolume * desiredACH) / 60; // 3. Outdoor Wet Bulb Temperature (Approximation using a psychrometric formula) // Convert Fahrenheit to Celsius for the formula var Tdb_C = (outdoorDryBulbTemp – 32) * 5 / 9; var RH_decimal = outdoorRelativeHumidity / 100; // Simplified approximation for Wet Bulb Temperature (Stull's formula variant) // This formula is typically for Celsius, so we convert Tdb to C, calculate Twb in C, then convert back to F. // Note: This is an approximation and real psychrometric charts are more accurate. var Twb_C = Tdb_C * Math.atan(0.151977 * Math.sqrt(outdoorRelativeHumidity + 8.313659)) + Math.atan(Tdb_C + outdoorRelativeHumidity) – Math.atan(outdoorRelativeHumidity – 1.676331) + 0.00391838 * Math.pow(outdoorRelativeHumidity, 1.5) * Math.atan(0.023101 * outdoorRelativeHumidity) – 4.686035; var outdoorWetBulbTemp = (Twb_C * 9 / 5) + 32; // 4. Estimated Supply Air Temperature // Supply Air Temp = Dry Bulb – (Efficiency * (Dry Bulb – Wet Bulb)) var tempDropPotential = outdoorDryBulbTemp – outdoorWetBulbTemp; var estimatedTempDrop = (coolerEfficiency / 100) * tempDropPotential; var estimatedSupplyAirTemp = outdoorDryBulbTemp – estimatedTempDrop; // 5. Estimated Water Consumption (Gallons/Hour) // Rule of thumb: ~1.25 gallons per hour per 1000 CFM var waterConsumptionGPH = (recommendedCFM / 1000) * 1.25; // 6. Estimated Daily Electricity Cost // Cost = (Power in Watts / 1000) * Hours * Cost per kWh var dailyElectricityCost = (coolerPowerConsumption / 1000) * dailyOperatingHours * electricityCost; // 7. Estimated Daily Water Cost // Cost = Water Consumption (GPH) * Hours * Cost per Gallon var dailyWaterCost = waterConsumptionGPH * dailyOperatingHours * waterCost; // 8. Estimated Total Daily Operating Cost var totalDailyOperatingCost = dailyElectricityCost + dailyWaterCost; // Display Results var resultHTML = '

Calculation Results:

'; resultHTML += 'Room Volume: ' + roomVolume.toFixed(2) + ' cubic feet'; resultHTML += 'Recommended Cooler CFM: ' + recommendedCFM.toFixed(0) + ' CFM'; resultHTML += 'Outdoor Wet Bulb Temperature: ' + outdoorWetBulbTemp.toFixed(1) + ' °F'; resultHTML += 'Estimated Supply Air Temperature: ' + estimatedSupplyAirTemp.toFixed(1) + ' °F'; resultHTML += 'Estimated Water Consumption: ' + waterConsumptionGPH.toFixed(2) + ' gallons/hour'; resultHTML += 'Estimated Daily Electricity Cost: $' + dailyElectricityCost.toFixed(2) + "; resultHTML += 'Estimated Daily Water Cost: $' + dailyWaterCost.toFixed(2) + "; resultHTML += 'Estimated Total Daily Operating Cost: $' + totalDailyOperatingCost.toFixed(2) + "; resultHTML += 'Estimated Monthly Operating Cost: $' + (totalDailyOperatingCost * 30).toFixed(2) + "; document.getElementById('swampCoolerResult').innerHTML = resultHTML; } .calculator-container { background-color: #f9f9f9; border: 1px solid #ddd; padding: 20px; border-radius: 8px; max-width: 600px; margin: 20px auto; font-family: Arial, sans-serif; } .calculator-container h2 { text-align: center; color: #333; margin-bottom: 20px; } .calc-input-group { margin-bottom: 15px; display: flex; flex-direction: column; } .calc-input-group label { margin-bottom: 5px; font-weight: bold; color: #555; } .calc-input-group input[type="number"] { padding: 10px; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; width: 100%; box-sizing: border-box; } .calculator-container button { display: block; width: 100%; padding: 12px 20px; background-color: #007bff; color: white; border: none; border-radius: 4px; font-size: 18px; cursor: pointer; transition: background-color 0.3s ease; margin-top: 20px; } .calculator-container button:hover { background-color: #0056b3; } .calc-result { margin-top: 25px; padding: 15px; background-color: #e9f7ef; border: 1px solid #d4edda; border-radius: 4px; color: #155724; } .calc-result h3 { color: #155724; margin-top: 0; border-bottom: 1px solid #d4edda; padding-bottom: 10px; margin-bottom: 10px; } .calc-result p { margin-bottom: 8px; line-height: 1.5; } .calc-result p strong { color: #0e3c17; }

Understanding and Sizing Your Swamp Cooler (Evaporative Cooler)

Swamp coolers, also known as evaporative coolers, offer an energy-efficient and environmentally friendly alternative to traditional air conditioning, especially in hot, dry climates. Unlike AC units that use refrigerants to cool air, swamp coolers work on the simple principle of evaporation: as water evaporates, it absorbs heat from the air, causing the air temperature to drop.

How Swamp Coolers Work

The core mechanism involves a fan drawing hot, dry outdoor air through water-saturated pads. As the air passes through these wet pads, water evaporates, and the air loses heat, becoming cooler and more humid. This cooled, moistened air is then circulated into your home. For optimal performance, swamp coolers require an exhaust path for the air, typically an open window or door, to allow the humidified air to escape and prevent the indoor humidity from rising too high.

Benefits of Evaporative Cooling

Energy Efficiency: Swamp coolers use significantly less electricity than compressor-based air conditioners, often consuming 75% less energy.
Lower Operating Costs: Due to lower energy consumption and simpler mechanics, daily and monthly operating costs are typically much lower.
Natural Cooling: They use water and a fan, avoiding chemical refrigerants.
Adds Humidity: In arid regions, the added humidity can be a welcome benefit, preventing dry skin, irritated sinuses, and static electricity.
Fresh Air: They constantly draw in fresh outdoor air, rather than recirculating stale indoor air.

Limitations and Considerations

Climate Dependency: Swamp coolers are most effective in dry climates (low relative humidity). As humidity rises, the cooling effect diminishes significantly.
Ventilation Required: Proper ventilation is crucial. Without an open window or vent for air to escape, the indoor humidity will build up, reducing cooling efficiency and potentially leading to mold issues.
Maintenance: Regular maintenance, such as cleaning and replacing pads, is necessary to ensure efficiency and prevent mineral buildup.
Water Usage: While energy-efficient, they do consume water through evaporation.

Using the Swamp Cooler Sizing & Cost Calculator

This calculator helps you determine the appropriate size (CFM) for a swamp cooler for your space and estimates its potential performance and operating costs. Here's a breakdown of the inputs:

Room Length, Width, Height: These dimensions are used to calculate the total volume of the space you want to cool.
Desired Air Changes Per Hour (ACH): This indicates how many times per hour the air in your room should be completely replaced. For swamp coolers, a higher ACH (typically 20-40 for residential) is recommended to ensure effective cooling and air circulation.
Outdoor Dry Bulb Temperature: The current or average outdoor air temperature.
Outdoor Relative Humidity: The current or average outdoor humidity level. This is critical as it directly impacts the cooler's effectiveness.
Cooler Saturation Efficiency (%): This represents how close the cooler can bring the air temperature to the wet bulb temperature. Higher efficiency (e.g., 80-90%) means better cooling.
Cooler Power Consumption (Watts): The electrical power rating of the swamp cooler's motor and pump.
Electricity Cost ($/kWh): Your local electricity rate.
Water Cost ($/gallon): Your local water utility rate.
Daily Operating Hours: How many hours per day you plan to run the cooler.

Understanding the Results

Room Volume: The total cubic feet of your space.
Recommended Cooler CFM: Cubic Feet per Minute. This is the airflow capacity your cooler should have to achieve the desired air changes per hour in your room.
Outdoor Wet Bulb Temperature: This is the lowest temperature that can be achieved by evaporative cooling under the given outdoor conditions. It's a theoretical limit.
Estimated Supply Air Temperature: This is the approximate temperature of the air coming out of your swamp cooler, based on its efficiency and the outdoor conditions.
Estimated Water Consumption: The approximate amount of water the cooler will evaporate per hour.
Estimated Daily/Monthly Operating Costs: Projections for your electricity and water expenses based on your inputs.

By using this calculator, you can make an informed decision about the right swamp cooler for your needs and get a clear picture of its potential performance and running costs.