One Pound at a Time: How to Charge R-32 in Your 5-Ton Combo System Without Screwing It Up

🛠️ Tony’s Intro: It Ain’t Just a Jug and a Hose Anymore

Let me tell you, back in the day, charging a system was a lot more forgiving. R-22? You could eyeball it and still walk out with a cold house and a happy customer. But with R-32? Those days are gone. You’re dealing with a high-pressure, high-performance, mildly flammable refrigerant that doesn’t play around when it comes to charge level.

These newer 5-ton systems—like the ones in the Goodman R-32 collection over at The Furnace Outlet—require precision, proper tools, and safety. I’ve seen good techs get burned (figuratively and literally) trying to charge R-32 the same way they did R-410A or R-22.

So, whether you’re topping off a factory-charged condenser or doing a full charge on a new install with a long line set, this guide’s gonna walk you through it step-by-step—from tank handling to subcooling measurement to system performance checks. No shortcuts, no guesswork, just the right way to do it.

Let’s charge up. 🧢

 

🔍 What Makes R-32 Different?

R-32 is a single-component, A2L-class refrigerant—that means it’s mildly flammable, operates at high pressure, and is more environmentally friendly than the older stuff. It’s got a GWP of 675, which is way lower than R-410A’s 2088, making it a front-runner for the new generation of HVAC systems.

But because it’s A2L, safety rules change. For one, you need leak detectors that can sniff out R-32. You also can’t vent it to atmosphere, and your recovery machines and gauges need to be A2L rated. ASHRAE's refrigerant classification guidelines go into detail on what’s required.

It also moves heat better than R-410A, which means smaller charge amounts but tighter tolerances. Overcharge it, and you’ll lose efficiency or risk high-pressure lockouts. Undercharge it, and that coil will freeze before you even get back to your truck.

 

🧯 Safety First: Handling and PPE for R-32

Let’s not skip the important stuff—R-32 is flammable, and while it won’t explode like gasoline, it can ignite under the right conditions if you’re careless.

Here’s what I wear and recommend every time:

• Flame-resistant gloves and sleeves

• Safety glasses with side shields

• A2L-rated leak detector (Testo, Fieldpiece, or Bacharach make good ones)

• Ventilated work area or an exhaust fan if you’re charging indoors

Always keep a fire extinguisher nearby, rated for flammable gases (Class B). And check your tank valve—R-32 uses standard 1/4" flare connections, but it requires a cylinder with a dip tube if you’re charging in liquid.

The EPA’s SNAP program covers safety and allowable uses for flammable refrigerants like R-32.

 

⚖️ Before You Charge: Line Set Length, Factory Charge, and Scale Setup

Before you hook anything up, figure out your total refrigerant needs.

Most 5-ton condensers come with a factory charge good for up to 15 feet of line set. Beyond that, you’ll need to add refrigerant—typically about 0.6 oz per foot of additional copper line.

So let’s say you’ve got a 30-foot line set:

• First 15 feet = covered

• Extra 15 feet = 15 × 0.6 = 9 oz additional charge

You’ll need:

• A digital charging scale

• R-32 tank with a dip tube (for liquid charging)

• Manifold gauges or Bluetooth probes rated for A2L

Weigh everything. Don’t guess. Even a 2–3 oz error can cause a performance issue in R-32 systems.

 

🧊 Charging by Subcooling: The Best Method for R-32 Systems

Now let’s talk technique. For these systems, charging by subcooling is the most accurate method—especially for TXV/EEV-equipped systems.

Here’s how I do it:

1. Let the system stabilize—run for 10–15 minutes with full load

2. Measure liquid line pressure and temp at the service valve

3. Use your gauge or app to calculate actual subcooling

4. Compare that to the target subcooling in the installation manual

5. Add or remove refrigerant in small amounts until you hit target ±1°F

Target subcooling for Goodman 5-ton R-32 units usually falls around 10–15°F, but always check the exact spec. Goodman provides this in the technical manual or product data sheets, like the ones at goodmanmfg.com.

Charge liquid into the suction side slowly using a charging tee and a sight glass if needed.

 

🌡️ Charging by Superheat (If You Have a Piston)

If your 5-ton system uses a fixed orifice instead of a TXV (rare but possible), then you’ll need to charge by superheat.

Here’s the workflow:

1. Measure indoor wet bulb and outdoor dry bulb

2. Use a superheat chart to find your target superheat

3. Measure suction pressure and temperature

4. Calculate actual superheat

5. Adjust refrigerant charge to bring actual to target

Superheat should usually land around 8–15°F under full-load conditions. And if your indoor airflow is off, none of this matters. Always check airflow first—400 CFM per ton is your baseline.

HVAC School has a great podcast episode on superheat and subcooling charging that’s worth a listen if you want a refresher.

 

🧰 Fine-Tuning the Charge and Spotting Issues

Once you’ve nailed the subcooling or superheat, don’t just pack up and go. Observe the system:

• Listen for compressor surging or valve chatter

• Watch for frost on the suction line or coil

• Feel discharge temps—should be hot but not scalding

• Use a thermal imaging camera on the lineset if you’ve got one

Common signs of incorrect charge:

• Low charge: Low suction pressure, high superheat, poor cooling

• Overcharge: High head pressure, low subcooling, poor efficiency

• Non-condensables or moisture: Fluctuating pressures, noisy compressor

Always verify with readings—not guesswork.

 

🧃 What About Recovery and Top-Offs?

Let’s say the system is short on charge or you had to pull it down for a leak repair. Here’s how I handle it:

• Always recover the full charge if you’re opening the system

• Weigh it and label the recovery tank

• After repair, pull a deep vacuum (500 microns or lower)

• Recharge using scale + subcooling method

And if you’re topping off:

• Only add liquid refrigerant

• Charge slowly and in small bursts

• Monitor subcooling as you go—never charge by just pressure alone

A reminder—venting R-32 is illegal, so use an A2L-rated recovery machine and storage tank. AHRI has excellent guidelines on recovery and reclaim for flammable refrigerants.

 

🚫 Rookie Mistakes to Avoid

Let’s go over what NOT to do. I’ve seen these all in the field—and yeah, I’ve done a few myself back in the day:

• Charging vapor from the top of the tank (liquid only with dip tube)

• Forgetting to purge lines with nitrogen

• Charging too fast and slugging the compressor

• Using gauges or hoses not rated for A2L

• Leaving the tank in the sun while charging

Treat R-32 with respect and it’ll treat you right. Screw around, and you’ll be looking at callbacks, burned compressors, or worse.

 

🧠 Wrapping It Up with Tony

Look, charging a 5-ton R-32 combo system isn’t hard—but it ain’t forgiving either. You’ve gotta be sharp, deliberate, and dialed in. No guesswork. No “close enough.” Not with these new refrigerants.

Use the right tools. Measure twice. Keep your PPE on and make sure you hit your targets—not just pressures, but subcooling and superheat too. That's how you keep the system efficient, safe, and humming like it should.

If you’re looking to install one of these R-32 beasts the right way, I always recommend starting with a factory-matched unit like the ones you’ll find at The Furnace Outlet’s R-32 combo system collection. They’ve done the heavy lifting—matched models, pre-charged units, full documentation—so all you have to worry about is doing the job right.

Having some thermostat problems in regards to your R-32 5-ton system? Visit my guide: Brain Freeze.

Alright, that’s it for now. Keep your head in the charge, your gauges on the tank, and your service calls clean.

Catch you on the next hookup,
Tony the Trusted Tech 🧢