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Q&A – Vacuum Questions Answered

By Bryan Orr

In this episode of the HVAC School podcast, host Bryan dives deep into the topic of vacuum in HVAC and refrigeration systems. He addresses two questions from social media about vacuum, expanding them into a comprehensive discussion of best practices, common issues, and techniques for effective vacuum procedures.

Bryan starts by explaining where to ideally locate a vacuum pump when working on a refrigeration system. He emphasizes the importance of pulling from the largest volume locations possible, often at multi-position service valves on the compressor or wherever accessible ports are available. He notes that systems that have been in operation pose unique challenges due to refrigerant dissolved in the oil, which can significantly increase vacuum time.

The podcast then covers the “one hose method” for pulling vacuum, detailing the process of using a single large hose connected to the suction side with the core removed, while placing the micron gauge on the liquid side. Bryan explains how this method can be highly effective for new systems but may take longer for systems that have been in operation. He also discusses the importance of valve quality.

Key topics covered in the podcast include:

Ideal vacuum pump location in refrigeration systems
The “one hose method” for pulling vacuum
Challenges of vacuuming systems that have been in operation
Using heat and nitrogen to improve vacuum efficiency
Importance of quality valves and tools in vacuum procedures
Proper maintenance of vacuum pumps and micron gauges
Dealing with refrigerant dissolved in oil during vacuum
The science behind evaporation at the oil-vapor interface
Tips for speeding up vacuum in difficult conditions
Recommended resources for further learning about vacuum techniques

Get your copy of Review of Vacuum for Service Engineers at TruTech Tools HERE.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

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#deep vacuum #evacuation #hvac #micron #micron gauge #nitrogen #vacuum

Author:

Bryan Orr

Company: HVAC School

Position: Founder

Check out our most recent video

How to Evacuate an AC system, Full Vacuum Procedure

Our latest Podcast

HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

In this comprehensive session, Eric Kaiser walks through the critical importance of establishing proper user requirements before making equipment purchases. Drawing from real-world experiences in the HVAC industry, he demonstrates how poor upfront planning leads to costly mistakes, buyer’s remorse, and multiple equipment purchases. The discussion covers everything from selecting simple tools like screwdrivers to complex HVAC system installations for residential and commercial applications.

Eric begins with relatable examples that everyone can understand – like buying screwdrivers that don’t do the job you need them for, leading to accumulating multiple tools over time. He then escalates to more serious scenarios, sharing a story about a company that spent significant money switching business software twice because they failed to identify a crucial missing feature upfront. This pattern of inadequate planning costs businesses and homeowners thousands of dollars and countless hours of frustration.

The heart of the presentation focuses on a structured approach to equipment selection that prioritizes needs over wants. Eric introduces a step-by-step process that includes defining intended use, conducting thorough assessments, categorizing requirements as needs versus wants, and performing systematic candidate evaluation. He demonstrates this methodology using electrical meter selection, showing how 38 potential options can be narrowed down to just two viable candidates through careful analysis of features like amperage capability, True RMS measurement, and accuracy requirements.

The session expands into HVAC system selection, where the stakes are much higher. Participants share valuable insights about customer expectations, from wanting to know when quiet systems are running (leading to flag solutions on registers) to dealing with customers who expect their new heat pump to feel as warm as their old poorly-designed system. Eric emphasizes that understanding customer expectations often differs from understanding their stated wants, requiring skilled questioning to uncover the real requirements for comfort, noise levels, and operational preferences.

Key Topics Covered

The Cost of Poor Planning: Real examples of expensive mistakes from inadequate user requirements, including business software failures and HVAC mismatches
Structured Selection Process: Step-by-step methodology for equipment selection from initial use definition through final verification and purchase
Needs vs. Wants Prioritization: Framework for distinguishing between essential requirements and desirable features to avoid decision paralysis
Electrical Meter Selection: Detailed walkthrough showing how to narrow 38 options to 2 viable candidates using systematic evaluation criteria
HVAC System Selection Complexities: Load calculations, customer expectation management, and the importance of understanding actual usage patterns
Customer Psychology and Expectations: Understanding why customers may want noise from systems, visual confirmation of operation, and familiar operational feel
Commercial Equipment Considerations: Rooftop unit replacement challenges, curb adapters, crane access, and the complexity of retrofit installations
Installation and Commissioning: The critical role of proper system setup, customer training, and setting realistic expectations for new equipment operation
Risk Assessment in Selection: How complexity and potential failure costs should determine the formality and thoroughness of your selection process
Data Collection for Future Decisions: The value of documenting system performance during routine maintenance to inform future replacement decisions
Hidden Costs and Considerations: Factors like electrical requirements, ductwork compatibility, equipment accessibility, and service support that impact long-term ownership costs

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 7th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android

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