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8 Common HVAC Installation Mistakes

Installing a new HVAC system is a significant investment for any homeowner. It’s essential to ensure that the installation is done correctly to avoid any future problems or costly repairs. However, even with the best intentions, HVAC installation mistakes can happen. In this article, we’ll discuss eight common HVAC installation mistakes and how to avoid them.


Planning is Key: Don’t rush into installation without considering your needs, budget, and desired climate control. Consult a professional for proper sizing and recommendations.

Location Matters: Position your HVAC unit thoughtfully, considering airflow, noise, access for maintenance, and clearance from obstacles like windows or vegetation.

Ductwork Done Right: Ensure proper ductwork design and installation to avoid leaks, blockages, and inefficient air distribution. Leaky ducts can waste energy and money.

Electrical Safety First: Always involve a qualified electrician for any electrical work related to your HVAC system. Improper wiring poses serious safety risks.

Filter Fit Matters: Choose the right air filter for your system and replace it regularly to maintain optimal performance and indoor air quality.

Don’t Skip Insulation: Ensure proper insulation around your HVAC system and ducts to prevent heat loss and improve efficiency.

Testing & Commissioning: Don’t assume everything works perfectly. Have a qualified technician test and commission your system after installation to ensure it operates safely and effectively.

Maintenance Matters: Implement a regular maintenance schedule to keep your HVAC system running smoothly and prevent costly breakdowns.

Mistake #1: Improper Sizing

One of the most common mistakes in HVAC installation is improper sizing. If the system is too small, it will struggle to keep your home at a comfortable temperature, leading to increased energy bills and a shorter lifespan for the unit. On the other hand, if the system is too large, it will cycle on and off frequently, causing unnecessary wear and tear and higher energy costs.

To avoid this mistake: Make sure to have a professional HVAC technician perform a load calculation to determine the appropriate size for your home.

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Mistake #2: Incorrect Refrigerant Charge

The refrigerant charge is the amount of refrigerant in the system. If the charge is too low, the system will not cool your home efficiently, and if it’s too high, it can cause damage to the compressor. It’s crucial to have the correct refrigerant charge to ensure optimal performance and longevity of your HVAC system.

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Mistake #3: Poor Airflow

Proper airflow is essential for an HVAC system to function correctly. If the airflow is restricted, it can cause the system to work harder, leading to increased energy bills and potential damage to the unit. Common causes of poor airflow include dirty air filters, blocked vents, and improperly sized ductwork.

To avoid this mistake: Make sure to change your air filters regularly and have your ductwork inspected and cleaned if necessary.

Mistake #4: Incorrectly Placed Outdoor Unit

The outdoor unit of an HVAC system should be placed in an area with proper airflow and protection from the elements. If the unit is placed in an area with poor airflow, it can cause the system to overheat, leading to potential damage. Additionally, if the unit is exposed to harsh weather conditions, it can cause premature wear and tear.

To avoid this mistake: Make sure to have a professional HVAC technician assess the best location for your outdoor unit.

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Mistake #5: Poorly Sealed Ductwork

Leaky ductwork can lead to significant energy loss and decreased efficiency of your HVAC system. It’s essential to have your ductwork properly sealed to ensure that the conditioned air reaches its intended destination. Leaky ductwork can also lead to poor indoor air quality and potential health issues.

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Mistake #6: Incorrectly Sized Ductwork

Similar to improper sizing of the HVAC system, incorrectly sized ductwork can also cause issues with airflow and efficiency. If the ductwork is too small, it can restrict airflow, leading to increased energy bills and potential damage to the system. On the other hand, if the ductwork is too large, it can cause the system to short cycle, leading to unnecessary wear and tear.

Mistake #7: Improperly Installed Thermostat

The thermostat is the control center of your HVAC system, and it’s essential to have it installed correctly. If the thermostat is not installed correctly, it can cause issues with temperature control and lead to increased energy bills. Additionally, if the thermostat is not calibrated correctly, it can cause the system to run longer than necessary, leading to unnecessary wear and tear.

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Mistake #8: Skipping Regular Maintenance

Regular maintenance is crucial for the longevity and efficiency of your HVAC system. Skipping routine maintenance can lead to issues with airflow, refrigerant levels, and overall performance. It’s essential to have a professional HVAC technician perform regular maintenance to catch any potential problems before they become costly repairs.

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Why Choose MSH Engineers for Your HVAC Design?

MSH Engineers is the premier choice for all your HVAC design needs. We have a team of experienced and qualified engineers who are passionate about creating comfortable, energy-efficient, and sustainable HVAC systems. We take the time to understand your unique needs and requirements, and we work closely with you to develop a custom-designed system that meets your budget and exceeds your expectations.

When you choose MSH Engineers for your HVAC design, you can be confident that you are getting the best possible value for your money. We are committed to helping you create a comfortable, energy-efficient, and sustainable environment for your home or business.

We provide expert services on the most difficult projects to device a comprehensive solution on time. We go above our scope of work to provide total customer satisfaction with competitive pricing to our clients. We work with our clients to not only meet their needs but exceed them. 

MSH has served as prime consultants subbing Electrical or Structural Engineering if need be. The principals are easily accessible to the client for feedback and friendly advice.

Contact us today to schedule a free consultation!

MSH Engineers provides a variety of services, including:
  1. HVAC Design Services
  2. Plumbing Design Services
  3. Sprinkler design service
  4. Fire Protection Design Service
  5. Light Design Service
  6. Fire Alarm System Design
  7. Engineering Consultants
  8. Electrical Engineering Consultancy Services
  9. Mechanical Engineering Consultancy Services
  10. Civil Engineering Consultancy Services
  11. Infrastructure Engineering Consultancy Services
  12. Building Services Consulting Engineers


HVAC installation mistakes can be costly and lead to issues with efficiency, comfort, and the lifespan of your system. By avoiding these common mistakes and having a professional HVAC technician perform the installation, you can ensure that your new system will function correctly and efficiently for years to come. 

Remember to schedule regular maintenance to keep your system running at its best.