Hoses/Types and Applications w/ NAVAC – Short #198

In this short episode of the HVAC School podcast, Bryan talks about hoses and their various types and applications, particularly focusing on NAVAC hoses.

Charging hoses (NAVAC: NH5 and NH5L) ideally shouldn't be longer than 5-6 feet, as the longer the hose, the more refrigerant it will hold. Manifold gauges also have leak points, so it's usually better to use probes instead of manifolds to help with charging. Charging hoses with ball valves (NH5S and NH5SC) can help you control the flow and are great for recovery. Whenever you use charging hoses, they will have a core depressor on one side only (usually the 45-degree side, if applicable); the right amount should be exposed, and the seal should be in good shape.

Larger-diameter hoses with higher burst pressure are advantageous for recovery (though it's better to have separate hoses for recovery and evacuation). Larger-diameter hoses of a shorter length will allow you to get a higher flow rate, including cases where you have 1/4″ connectors (though the F1028 & F1029 Rapid Y connection fittings can help out with those cases where you have 1/4″ connectors by giving you the ability to connect two 3/8″ hoses); hoses with a diameter of 3/8″ are usually the biggest recommended ones for recovery. NAVAC's recovery hoses are the NHR38AA and NHR38AB.

Evacuation hoses are even bigger. Some good evacuation hoses include the NH34AB and NH34AC; they are short 3/4″ hoses that are vacuum-rated and quite flexible. NAVAC also has smaller hoses, which tend to look more like recovery hoses. You do not want to use 1/4″ hoses and core depressors for evacuation, but they are good for charging.

Check out all of the hoses NAVAC has to offer at https://navacglobal.com/products-by-category/hoses-kits/.

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Author:

Bryan Orr

Company: HVAC School

Position: Founder

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Chris Hughes and Steve Rogers from The Energy Conservatory discuss TEC’s TrueFlow technology and its crucial role in predicting airflow issues in the sales process, particularly for heat pump retrofits. They explain how the TrueFlow app helps contractors accurately measure both static pressure and airflow in existing systems, enabling them to predict whether proposed equipment changes will work effectively. This is especially vital when considering the growing trend of replacing gas furnaces with heat pumps, as the airflow requirements can differ significantly.

The conversation delves into a detailed example of replacing an 80% efficient 48,000 BTU furnace with a heat pump. They demonstrate how the airflow requirement would nearly double from 652 CFM to 1,200 CFM, potentially causing the static pressure to quadruple due to Fan Law 2 principles. This dramatic increase could lead to significant performance issues if not properly addressed during the system design phase. The experts emphasize that using TrueFlow during the sales process allows contractors to identify potential problems and necessary modifications before installation rather than discovering issues during callbacks.

The discussion also covers the ideal workflow for system assessment and sales, starting with customer comfort evaluation and proper load calculations. It’s important to reduce loads through envelope improvements when possible, particularly in cold climates where heat pump retrofits are becoming more common. Proper system sizing often means going smaller rather than larger, contrary to common industry practices, and the worst HVAC systems are often found in expensive custom homes rather than tract housing.

Key Topics Covered:

TrueFlow technology and its role in system forecasting
Fan Law 2 and its impact on static pressure when changing airflow
Heat pump retrofit challenges and considerations
The importance of accurate load calculations
Dual fuel systems as a solution for cold climates
The relationship between airflow and static pressure
Sales process integration of technical measurements
Common issues with oversized equipment
The importance of envelope assessment
Methods for reducing system loads
Proper duct sizing and modification strategies
The role of proper filter sizing and selection
The benefits of flat-rate pricing for duct modifications
Training resources and support available for TrueFlow users

Check out TEC’s YouTube channel at https://www.youtube.com/@energyconservatory, and you can visit TEC’s website at https://energyconservatory.com/.

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.