AVOIDING 101 SERIOUS HVAC DESIGN MISTAKES

 

 

Table Of Contents

Chapter 1: Air Distribution

1.1. Max and Min VAV air quantities not shown on drawings.

1.2. Linear diffusers create drifts and comfort problems.

1.3. Flexible duct installation problems

1.4. Un-balanced duct branches.

1.5. Interconnecting duct loop arrangements.

1.6. Ceiling Return problems.

1.7. Diffusers dumping air at low flow.

1.8. Light troffers causing drafts and comfort problems.

1.9. Pressure dependent VAV system problems.

1.10. VAV terminal box operates with reduced capacity.

1.11. VAV terminal box operates with reduced capacity.

1.12. Flex duct installation problems.

1.13. Flex duct installation problems.

1.14. Diffusers create drafts and comfort problems.

1.14. Diffusers create drafts and comfort problems.

1.16. Excessive duct leakage causes problems.

1.17. Insufficient air flow from a VAV terminal box.

1.18. Terminal boxes do not open.

1.19. Terminal boxes do not close.

1.20. Steam Humidifiers soak ducts.

1.21. Duct Humidifiers cause water to collect in ducts.

1.22. Smudging occurs around ceiling diffusers.

1.23. Terminal boxes and diffusers generate noise.

1.24. High humidity occurs in courthouse occupancy.

1.25. Improperly sized diffusers.

1.26. Insufficient smoke control in VAV systems.

Chapter 2: Air Movement

2.1. Return fan usage.

2.2. Forward curved fans usage.

2.3. Parallel fan arrangement problems.

2.4 Airfoil blade type fans.

2.5. Centrifugal fan usage problems.

2.6 Variable pitch controls and vane-axial fans.

2.7. Fan vibration, pulsating and noise.

2.8. Multi-branch system and VAV fan surging.

2.9. VAV supply fan surges and hunts.

2.10. Filter bank diffuser plate installation problems.

2.11. Vane-axial fan installation causes noise and vibration.

2.12. Noisy fan operation and low air flow.

2.13 Outdoor air mixing box stratification.

2.14. Fan in plenum has reduced flow output.

2.15. New fan installation using excessive energy.

2.16. A reduction of airflow is observed in a ducted system.

2.17. Fan bearings constantly fail and have a short life span.

2.18. Fan motor drives constantly fail.

2.19. Overall system noise.

2.20. Large amounts of fan noise.

2.21. Fan system can not put out design airflow.

2.22. System effects cause deterioration in fan operation.

Chapter 3: Controls

3.1. Improperly installed airflow stations.

3.2. Proportional integral control use.

3.3. Velocity sensors improperly read.

3.4. VAV box furthest from fan short of air.

3.5. Duct static pressure controller can not adjust properly.

3.6. Fan over pressurizes duct system causing damage.

3.7. Supply-return fan tracking system malfunctions.

3.8. Building pressure constantly varies.

3.9. Return fan feedback problems create building pressure problems.

3.10. Improper building pressure sensor location.

3.11. VAV terminal sensor has insufficient velocity and airflow.

3.12. VAV box malfunctions on minimum airflow.

3.13. Pneumatic controllers have chaotic operation.

3.14. Fan adjustment control in a VAV system constantly hunts.

3.15. Terminal boxes continuously hunt.

3.16. Control configurations affect VAV system operations.

3.17. Velocity pressure signal control creates fan operation problems.

Chapter 4: Equipment (Boilers, Chillers, Cooling Towers, etc.)

4.1. Steam absorption machine continuously hunts.

4.2. Steam turbine chiller utilizes excessive amounts of steam.

4.3. Rooftop unit causes excessive vibration noise.

4.4. Hot water and condensate pumps produce noise and vibration.

4.5. Boiler shows signs of freezing damage.

4.6. Boiler cast iron sections are cracking.

4.7. Unstable water level in boilers.

4.8. Low pressure heating boiler shows signs of pitting corrosion.

4.9. Centrifugal refrigeration compressor has operating problems.

Chapter 5: Hydronics

5.1. Continuous check valve slam occurs.

5.2. Severe pitting occurring to chillers.

5.3. Corrosion occurring throughout entire hydronic system.

5.4. Corrosion occurring to cooling tower piping.

5.5. Steam traps blow by steam.

5.6. Malfunctioning steam pressure reducing stations.

5.7. Balancing valves do not facilitate system balancing.

Chapter 6: Interior Air Quality And Air Borne Contamination

Control.

6.1. Insufficient outdoor air creates IAQ problem.

6.2. System has insufficient total air supply.

6.3. VAV box minimum settings create IAQ problems.

6.4. Humidity levels climb above 60%.

6.5. Perimeter zones have IAQ problems.

6.6. Partitioned offices have air distribution problems.

6.7. Interior open office ventilation creates IAQ problems.

6.8. Half height partitions with closed bottoms create problems.

6.9. Wet air handler final filters cause serious problems.

6.10. Problems with dirty reheat coils.

6.11. Exhaust discharge works its way back into the building.

6.12. Nitrous Oxide buildup in Hospital Operating rooms

6.13. Bag In/Bag Out filtering system.

Chapter 7: Laboratories

7.1. Pressure dependent systems.

7.2. Fume hoods can not get sufficient makeup air.

7.3. Contaminated air escapes from Lab to surrounding areas.

7.4. Negative room can not get makeup air via normal crackage.

7.5. Conventional VAV fume hoods can create room imbalances.

7.6. Fume hoods don't remove particulate matter in hood.

7.7 Fumes hoods don't exhaust all fumes within the hood.