This tech tip is a companion piece to a recent short podcast episode about the same topic. It contains links to the specific products mentioned in that podcast. You can also learn more about NAVAC products as a whole at https://navacglobal.com/.

Our trade has a lot of cool tools. But while we’re thinking about how to expand our tool arsenal with fancy vacuum pumps, recovery machines, and torque wrenches, we often overlook the humble hose. It’s not like we need them to charge and recover refrigerant or evacuate a system or anything, right? (/s) 

That said, the process of selecting a hose isn’t as easy as picking one up off the shelf at the nearest supply house and using it for everything. Length, width, and fittings all matter when you pick out a hose—and different tasks have different best practices.

This tech tip will be a quick guide explaining how to select the right hose for the right task. It’ll also include some recommendations by NAVAC, including several that were mentioned in this tech tip’s companion podcast episode.

Charging (and Test) Hoses

The trusty manifold is pretty much the universal symbol for charging in the HVAC world. However, even the best ones can introduce leak points, especially as seals start to wear out over time. Instead, we recommend using probes, a charging tee, and a dedicated charging hose. Charging hoses usually have ¼” fittings on each end. The working pressure is usually around 800 PSI, and the burst pressure is around 4000 PSI.

While shorter hoses have their advantages when it comes to mass flow rate (when it comes to evacuation, at any rate) and minimizing losses, it’s possible for hoses to be so short that they’re stiff and difficult to work with. You certainly can use hoses that are 3–4 feet, but we tend to find that hose lengths of 5–6 feet work best. They’re not so long that you’re getting tangled in them and holding a ton of refrigerant, but they’re also not super stiff.

Some charging hoses also have ball valves to help you control the flow of refrigerant. You may end up trapping a little bit of refrigerant in the hoses, but these can come in handy if you want to have more control over the refrigerant going into or out of the system. 

Charging hoses have slightly different fittings on each end: one straight fitting and one at a 45° angle. The angled end hooks up to the system, and the straight end hooks up to the tank. There are usually core depressors in the 45° end (left below). 

These core depressors push down on the Schrader core when you hook up the hose so that the refrigerant can flow through the setup. When it comes to hose upkeep, make sure the right amount of core depressor is exposed and that the seal stays in good shape.

Some NAVAC tools we like:

• Refrigerant hose without ball valves: NH5S
• Refrigerant hose with ball valves: NH5SC
• A2L-compatible refrigerant hose without ball valves: NH5L
• Core depressor tool (backseat control valve): F1031
• Reverse thread adapter for A2Ls: F2010
• Liquid charging adapter (¼”): F2008
• Liquid charging adapter (5/16”): F2009  

Recovery Hoses

As with the charging hoses, you’ll want hoses with a high burst pressure, around 4000 PSI. However, the burst pressure is slightly less critical because we don’t recover refrigerant from running systems. 

Speed is usually more valuable for recovery than charging, so larger-diameter hoses are advantageous because they let you have a higher flow rate. A shorter hose length and core removal tools (CRTs) will also allow you to get a higher flow rate. Even though you may have 1/4″ connectors that restrict the flow for a short period, a larger hose diameter still improves the flow rate overall.

Normally, a diameter of ⅜” is the largest recommended size for recovery hoses. You can also use these hoses with ¼” connectors when you use the F1028 & F1029  Rapid Y connection fittings. These fittings give you the ability to connect two 3/8″ hoses to a ¼” connector. 

Some NAVAC tools we like:

• Big Boy recovery hose (¼”–¼” fitting): NHR38AA 
• Big Boy recovery hose (¼”–⅜” fitting): NHR38AB

Evacuation Hoses

Evacuation hoses are even bigger than recovery hoses; that alone is a good enough reason to have separate evacuation and recovery hoses. However, contamination is also a concern, so it’s best to have one set of hoses that may have refrigerant and oil residue in them from recovery and one that doesn’t. 

Evacuation hoses should be vacuum-rated and flexible regardless of length. The absolute best are large—up to ¾” in diameter—and short, usually around three feet. As with recovery, mass flow is critical for evacuation, so the larger diameter and shorter distance help a lot. We also want to use CRTs, not core depressors, to take the cores out entirely.

With larger hoses and a new or small system, we can do a one-hose evacuation that connects straight from the vacuum pump to the CRT with the micron gauge on the opposite side. However, it’s best to have two hoses available for large or tough vacuum jobs. In the latter case, ¼” tee connectors can come in handy for two-hose setups.

Some NAVAC tools we like:

• Evacuation hose (½”): NHB1 (3/8″–1/4″) & NHB2 (1/2″–1/4″)
• Big Boy evacuation hose (⅜”): NH38BB
• Big Boy evacuation hose (¾”): NH34AB (1/4″–3/8″) & NH34AC (1/4″–1/2″)
• ¼” tee connector: F1030

Conclusion

In conclusion, form follows function; charging hoses are more compact with high burst pressure so that we can add refrigerant to a working system, whereas charging and evacuation hoses are much more mass flow-oriented for speedy service. On a charging hose, the main thing to watch out for is the core depressor, which is usually on the angled end that attaches to the system; in the case of recovery and evacuation, you’ll most likely make use of a CRT. 

To keep things really short and sweet, use a ¼” hose for charging but definitely not for pulling a vacuum.