Air Flow Temperature Rise is determined by dividing the heat input (in BTU/hr) by the product of the airflow rate (in CFM) and a constant factor of 1.08. The formula is ΔT (°F) = Heat Input (BTU/hr) / (Airflow (CFM) * 1.08). It calculates the change in air temperature resulting from the heat input and airflow in a system.
Air Flow Temperature Rise Calculator
| Heat Input (BTU/hr) | Airflow (CFM) | Temperature Rise (°F) |
|---|---|---|
| 10,000 | 200 | 5.4 |
| 20,000 | 400 | 5.4 |
| 30,000 | 600 | 5.4 |
| 40,000 | 800 | 5.4 |
| 50,000 | 1000 | 5.4 |
| 60,000 | 1200 | 5.4 |
In this table, we calculate the temperature rise (ΔT) for different heat inputs (Q) and airflow rates (Q = CFM) using the formula:
ΔT (°F) = Q (BTU/hr) / (CFM x 1.08)
The constant 1.08 is used for simplification and estimation. The values in the table are approximate results and can vary depending on the specific conditions and equipment used.
FAQs
1. What is the formula for temperature rise in airflow? The formula to calculate temperature rise in airflow is: Temperature Rise (in degrees Fahrenheit) = (Heat Input in BTU/hr) / (Airflow in CFM * 1.08)
2. How do you calculate temperature rise? Temperature rise is calculated by dividing the heat input (in BTU/hr) by the product of airflow (in CFM) and a constant factor of 1.08.
3. How do you calculate BTU for air flow and temperature? BTU (British Thermal Units) can be calculated using the formula: BTU = (Airflow in CFM) x (Temperature Difference in °F) x 1.08
4. What is the air temperature rise on a furnace? The air temperature rise on a furnace depends on its design and settings. A common range for residential furnaces is 30-70°F.
5. How do you calculate temperature rise with CFM? Temperature rise can be calculated by dividing the heat input (in BTU/hr) by the product of airflow (in CFM) and the constant factor 1.08.
6. How do you measure air flow temperature? Airflow temperature can be measured using a thermometer or temperature sensor placed within the airflow stream.
7. How many BTU does it take to raise air 1 degree? It takes approximately 1 BTU to raise 1 pound of air by 1 degree Fahrenheit.
8. How to calculate heat required to raise temperature of air? The heat required to raise the temperature of air is calculated using the formula: Heat (in BTU) = (Mass of Air in pounds) x (Temperature Rise in °F) x 1.08
9. How is airflow affected by temperature? Airflow can be affected by temperature changes through the principles of density and expansion. As air temperature increases, it becomes less dense, leading to changes in airflow patterns and behaviors.
10. How do you calculate BTU from temperature rise? BTU can be calculated from temperature rise using the formula: BTU = (Airflow in CFM) x (Temperature Rise in °F) x 1.08
11. How do you calculate air flow from pressure and temperature? Airflow can be calculated using the Ideal Gas Law: Airflow (in CFM) = (Pressure in psia) x (Volume in cubic feet) / (Gas Constant x Temperature in Rankine)
12. How many CFM is a 100,000 BTU furnace? The CFM rating of a furnace can vary, but a rough estimate is around 800-1,200 CFM for a 100,000 BTU furnace.
13. How do you conduct a temperature rise on a furnace? To conduct a temperature rise test on a furnace, you measure the incoming and outgoing air temperatures, calculate the temperature rise, and compare it to the manufacturer’s specifications.
14. How quickly should a furnace raise the temperature? The speed at which a furnace raises the temperature depends on its capacity and design. Generally, residential furnaces aim to heat the air to the desired temperature within a few minutes.
15. How much does air temperature change with height? The air temperature can decrease with height in the troposphere at an average rate of about 3.6°F (2°C) per 1,000 feet of elevation.
16. How many CFM does an 80,000 BTU furnace need? An 80,000 BTU furnace typically requires around 640-960 CFM of airflow.
17. How many CFM is a 70,000 BTU furnace? A 70,000 BTU furnace may require approximately 560-840 CFM of airflow.
18. How many CFM is a 60,000 BTU furnace? A 60,000 BTU furnace may need around 480-720 CFM of airflow.
19. What is the most accurate way to measure air temperature? The most accurate way to measure air temperature is using a calibrated digital thermometer with a high level of precision.
20. How do you calculate flow rate from temperature? Flow rate is not directly calculated from temperature alone; it typically involves the consideration of other factors like pressure and volume.
21. What are the three methods of directly measuring air flow? The three common methods of directly measuring air flow are using an anemometer, a pitot tube, or a hot-wire anemometer.
22. How much does air temperature change per 1,000 feet? Air temperature typically decreases by about 3.6°F (2°C) per 1,000 feet of elevation.
23. What is a temperature increase of 1 degree? A temperature increase of 1 degree refers to a change of 1 degree Fahrenheit (or 1 degree Celsius) in temperature.
24. How much heat is required to raise the temperature by that amount in BTU? To raise the temperature of 1 pound of air by 1 degree Fahrenheit, it requires approximately 1 BTU of heat.
25. How do you calculate the rate of air temperature change? The rate of air temperature change can be calculated by dividing the temperature change (in °F) by the change in altitude (in feet) or by using temperature lapse rate formulas.
26. How much does air expand per degree Fahrenheit? Air expands at a rate of approximately 0.002 percent per degree Fahrenheit increase in temperature.
27. What is the relationship between temperature and flow rate? Temperature and flow rate are related in air systems, as temperature changes can affect the density of air, which in turn can impact flow rates.
28. Does temperature affect CFM? Yes, temperature can affect CFM as changes in temperature can influence the density of air and, consequently, the volumetric flow rate.
29. Where does air temperature increase? Air temperature generally increases with height in the stratosphere due to the absorption of ultraviolet radiation by ozone.
30. How many BTU do I need for a 20×20 room? For estimation, a 20×20 room may require approximately 12,000-18,000 BTUs depending on insulation and climate.
31. How do you convert BTU to CFM? BTU and CFM are not directly convertible, as BTU is a measure of heat and CFM is a measure of airflow. The conversion depends on the specific application and the heat load.
32. How does BTU relate to temperature? BTU (British Thermal Units) is a measure of heat energy. It quantifies the amount of energy required to raise the temperature of a substance, like air, by a certain amount.
33. How do you calculate air flow? Airflow is calculated using various methods depending on the application, such as using anemometers, pitot tubes, or flow meters.
34. What is the formula for air flow rate? The formula for air flow rate depends on the specific system and measurement method. Common formulas include Q = VA (volumetric flow rate), Q = m(dot) (mass flow rate), and others.
35. How do you increase air flow to a pipe? Airflow to a pipe can be increased by increasing the pressure, adjusting the fan or blower settings, or modifying the ductwork to reduce resistance.
36. How much CFM do I need for 2000 square feet? For estimation, a 2,000 square feet area may require around 1,200-1,800 CFM of airflow depending on factors like insulation and climate.
37. How big of a house can a 100,000 BTU furnace heat? A 100,000 BTU furnace can typically heat a house of approximately 2,000-3,000 square feet, but other factors like insulation and climate should be considered.
38. How many square feet will an 80,000 BTU furnace heat? An 80,000 BTU furnace can heat a house of roughly 1,600-2,400 square feet, but insulation and climate factors also play a role.
39. What is a good temperature rise on a gas furnace? A typical temperature rise for a gas furnace is around 30-70°F, depending on the furnace design and settings.
40. What is the typical temperature rise for a standard efficiency gas furnace? A standard efficiency gas furnace may have a temperature rise within the range of 50-70°F.
41. What should the temperature difference be between supply and return? The temperature difference between supply and return air in a furnace system is typically referred to as the “temperature rise” and can vary but often falls within the 30-70°F range.
42. What should I set my furnace to in extreme cold? In extremely cold conditions, it is advisable to set your furnace to a temperature that provides comfort while considering energy efficiency. A common setting is around 68-72°F.
43. How hot can a homemade furnace get? The maximum temperature a homemade furnace can reach depends on its design and materials used, but it should be operated with caution and following safety guidelines.
44. Does air temperature increase with increasing height? Air temperature generally decreases with increasing height in the lower atmosphere (troposphere). However, it can increase in the stratosphere due to ozone absorption.
45. Why does air temperature increase with height? In the stratosphere, air temperature increases with height because of the absorption of ultraviolet (UV) radiation by ozone molecules, leading to a temperature inversion.
46. How is air temperature related to height from the ground? In the troposphere, air temperature typically decreases with increasing height due to the adiabatic lapse rate and reduced air pressure.
47. What size AC goes with an 80,000 BTU furnace? The size of an air conditioner that complements an 80,000 BTU furnace depends on factors such as the size of the space, climate, insulation, and specific load calculations.
48. What size duct do I need for a 12×12 room? The size of duct needed for a 12×12 room depends on various factors, including the HVAC system’s capacity, design, and airflow requirements. It would typically range from 6 to 8 inches in diameter for residential applications.
49. How many CFM is a 2-ton furnace? A 2-ton furnace may require approximately 800-1,200 CFM of airflow, depending on its design and specific application.
50. How many CFM do I need for a 100,000 BTU furnace? For a 100,000 BTU furnace, you may need around 800-1,200 CFM of airflow, depending on the furnace’s design and specifications.
51. How many CFM do I need for a 40,000 BTU furnace? For a 40,000 BTU furnace, you may need approximately 320-480 CFM of airflow, depending on the furnace’s design and specific application.
52. What size furnace do you need for a 1,000 square foot house? For a 1,000 square foot house, a furnace with an output of 40,000-60,000 BTUs may be suitable, but insulation and climate should be considered.
53. How many CFM does an 80,000 BTU furnace need? An 80,000 BTU furnace may require approximately 640-960 CFM of airflow, depending on its design and specifications.
54. How many CFM is a 70,000 BTU furnace? A 70,000 BTU furnace may need around 560-840 CFM of airflow, depending on its design and specific application.
55. Can I use a thermometer to measure air temperature? Yes, you can use a thermometer to measure air temperature. Digital thermometers are commonly used for accuracy and convenience.
56. How can I measure the temperature of the air at home? You can measure the temperature of the air at home using a thermometer, a thermostat, or a digital temperature sensor.
57. How do you manually calculate flow rate? Flow rate can be manually calculated using various methods depending on the application, such as using a flow meter, timing a volume of fluid, or using empirical formulas.
58. What is the easiest way to calculate flow rate? The easiest way to calculate flow rate is to use a flow meter or sensor designed for the specific application, as it provides direct and accurate measurements.
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