Effective ways of Duct Design
Ducts are conduits or passages used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. The ducts are used for supply air, return air, and exhaust air. In common practice, we found mistakes in Aspect ratio also bending in ducting is not done correctly. Therefore to reduce the errors, following are the some guidelines for ducting for heating, ventilation and air conditioning.
By using these guidelines we can minimize the velocity losses, friction losses, etc.
- Larger duct aspect ratio have more heat gain than ducts with small aspect ratio, with each carrying the same air quantity.
- Ducts carrying small air quantities at a low velocity have a greatest heat gain.
- The addition of insulation to the duct decreases duct heat gain.
- To reduce noise, air velocity should be within permitted range.
- If you have to change the direction of ducting, then avoid sudden change in direction.
- Angle of divergence should be less than 20 degree.
- Aspect ratio should be within 1 to 4. Aspect ratio is the ratio of long side to short side of duct.
- Increase the aspect ratio increases both the installation cost and operating cost.
- Acoustic duct insulation insulation material for sheet metal ducts used in heating, ventilating and air conditioning, provides an optimum combination of efficient sound absorption, low thermal conductivity and minimal airstream surface friction.
- Ventilation systems require thermal insulation in order to restrict and control heat loss.
