Installation Guide: What Mike Learned About Setting Up a 3 Ton Horizontal A-Coil

This guide will walk you through everything from unpacking to startup checks. Use it in conjunction with your coil’s manufacturer instructions and local code requirements.

3 Ton Horizontal Goodman Cased Coil with Built-in TXV - CHPTA3630B3

---

📦 1. Pre-Installation: Planning & Preparation

Before you touch your drill or torch, Mike insists you get your ducks in a row. This stage dramatically reduces mistakes, back-tracking, and safety issues.

1.1 Safety First (⚠️)

• Cut all power to the HVAC system (furnace/air handler + condensing unit). Multiple breakers may be involved.

• Wear safety glasses, gloves, protective clothing.

• When brazing, use quenching cloths to protect painted surfaces and nearby wiring from heat.

• Always follow local electrical, refrigeration, and building codes. The manufacturer’s manual can’t override your jurisdiction.

• Refrigerant handling: If your system uses R-32 (as in CHPTA models), ensure you follow EPA rules and use proper equipment rated for R-32.

1.2 Inspect the Shipment

• Check for shipping damage, dents, bent fins, or missing parts.

• Verify the model, capacity, built-in TXV, directionality (left or right), and compatibility with your system.

• If anything is wrong, file a claim before proceeding.

1.3 Tools & Materials Checklist

Here’s what Mike always double-checks before he starts:

 

You can also refer to a practical DIY evaporator coil installation guide for reference. The Furnace Outlet

1.4 Review Manufacturer’s Instructions

For Goodman horizontal two-way coils, the manufacturer provides a specific installation manual. It stresses safety, correct airflow direction, sealing, and drain connections. 

Always keep that PDF/manual open while working.

---

🧩 2. Positioning & Mounting the Coil Cabinet

With prep done, now it’s time to place your coil in the correct orientation and secure it properly.

2.1 Orientation & Airflow Direction

• Goodman’s horizontal two-way coils are bi-directional: they can be installed for left or right airflow depending on which side gives better access. 

• The coil must be installed on the discharge side of the furnace (i.e., between the furnace and the plenum). 

• If your setup is reversed (coil first then furnace), that is incorrect.

2.2 Alignment, Clearances & Slope

• Make sure the coil cabinet is level side to side, but tilt slightly (≈ ½" over its depth) toward the drain connection to enable gravity drainage. 

• Avoid pitching more than 5/8"; too steep a slope may cause water “blow-off” via auxiliary drain. adpnow.com

• Maintain proper clearances for servicing: e.g., refrigerant lines usually need ≥ 24" clearance for service access. documents.alpinehomeair.com

• In unconditioned or humid areas, wrap the outer casing with 2" fiberglass vapor barrier insulation to prevent sweating. 

2.3 Attaching to the Furnace

• Use the Z-bracket included in the kit when your coil is larger than your furnace width.

• If coil and furnace depths differ, use a field-fabricated transition to center the openings.

• Use sheet-metal screws and brackets (front, top, back) to firmly attach coil to the furnace. Seal all joints with foil tape or HVAC mastic for airtightness. 

• Remove any shipping brackets present before final mounting. HORIZONTAL TWO-WAY COIL

2.4 Duct Flange Attachment

• The bottom supply duct flange is often shipped unattached. Slide and screw it into place with a 5/16" screw at the center. 

• Use mastic or sealant at the joints between coil, furnace, and later the plenum to avoid air leakage. 

At this point, your coil should be solidly mounted, level (with slight slope), sealed to the furnace, and ready for lines.

---

❄️ 3. Refrigerant Line Connection & Brazing

This is a critical phase. Poor brazing or unpurged lines can cause system failures down the road.

3.1 Line Routing & Sizing

• Use refrigerant-grade copper tubing sized per the outdoor unit manufacturer’s recommendation. 

• Route suction (larger) and liquid (smaller) lines with minimal bends and gradual curves. Avoid sharp bends that can restrict flow.

• Insulate the suction line thoroughly. Extend insulation over the TXV sensing bulb area. 

• Position TXV sensing bulb in a horizontal run of the suction line, on the 10 or 2 o'clock position for best reading. 

3.2 Brazing & Purge

• Flow dry nitrogen through the lines during brazing to prevent oxidation inside the tube.

• Use a silver-based alloy (at least 5% silver) to ensure strong joints. 

• Use quenching cloth/wet rag immediately after brazing to cool adjacent parts and prevent heat damage.

• Deburr and clean tube ends before brazing to ensure a solid joint.

• After brazing, check for continuity, leaks, or weak joints with nitrogen at moderate pressure.

3.3 Leak Testing & Evacuation

• Pressurize the system (often with nitrogen) and check all joints for leaks using a leak detector or bubble solution.

• Once leak-free, evacuate the system using a vacuum pump to at least 500 microns (or per manufacturer spec).

• Hold vacuum for a period (30–60 minutes) to confirm no leaks.

• After evacuation, keep the service valves closed until you’re ready to charge.

---

🌊 4. Condensate Drainage Setup

Even though it’s less glamorous than refrigerant lines, proper condensate drainage is vital.

4.1 Primary & Secondary Drains

• The coil has a primary drain pan and often an auxiliary/secondary drain for overflow safety. 

• Primary and secondary drains must run separately—never combine them. 

• Secondary drain must terminate somewhere visible, so the homeowner knows when the primary is clogged.

4.2 Drain Line Pitch & Trap

• Ensure drain lines slope ¼" per foot downward away from the coil for gravity drainage. 

• Insert a trap at the base of the coil drain: the trap depth should be ≥ 1" or enough to ensure positive liquid seal.

• In installations above ceilings or sensitive areas, always use an auxiliary drain pan under the coil enclosure.

• Avoid excessive torque when connecting the drain fittings—over-tightening can crack the plastic drain connector. 

4.3 Preventing Blow-Off

• In horizontal-left applications (left-side drain), high airflow can cause water blow-off. Use the blow-off bracket included in the kit on the left side of the drain pan to protect against this

• Do not pitch the coil excessively (more than 5/8") to avoid blow-off. 

---

🔧 5. TXV / Metering & Charge Preparation

Because your coil has a built-in TXV, the metering device side is mostly set—but you still need to position the bulb and set up for proper superheat.

5.1 TXV Bulb Positioning & Mounting

• The TXV sensing bulb is shipped attached to the coil. After you connect the field line, carefully reposition it to the suction line in a horizontal run. 

• The bulb must make direct contact with the suction line—clamp it with mounting straps firmly, but not crushing.

• Insulate both the suction line and the sensing bulb to reduce ambient influence on readings. 

5.2 System Matching & Charge

• The indoor coil and outdoor condensing unit must be AHRI-matched (or approved mismatch). Unmatched systems may void warranties. 

• Set airflow at the recommended CFM (e.g. 400 CFM per ton is common). Don’t allow excessive pressure drop across coil (often ≤ 0.30" WC).

• Charge based on superheat/subcooling method (following the outdoor unit’s spec). Since you have TXV, adjust superheat via TXV per outdoor unit chart. 

• Label the system: date, refrigerant weight, ambient condition, and installer notes.

---

✅ 6. Startup & Testing

This is the make-or-break phase where all your careful work either pays off or shows flaws.

6.1 Power Up & Initial Checks

• Restore power to the system.

• Leave system OFF at first; confirm blower or fan motor spins freely and no strange sounds.

• Open service valves on the condensing unit.

6.2 System Run Checks

• Turn system to cooling mode.

• Monitor suction and discharge pressures via the gauge set.

• Verify temperature drop across the evaporator coil (ΔT). A typical target is 16–22°F (or as per manufacturer).

• Check for leaks again while under pressure (bubble check or electronic leak detector).

• Listen for unusual noises (vibration, gurgle, hissing).

• See if condensate drains properly—some water should flow out under normal humidity load.

• After 15–20 minutes of stable operation, re-check refrigerant charge, temps, pressures, and superheat/subcooling.

6.3 Commissioning & Documentation

• Ask homeowner to monitor system for the first few days—check for leaks, indoor comfort, noise.

• Provide maintenance instructions (filter changes, coil cleaning, checking drain, etc.).

• Keep your detailed notes: line lengths, bends, charge, trap type, etc.—helps future servicing.

---

🔍 7. Mike’s Troubleshooting Tips

If you hit a snag, here are some of the issues Mike has run into and how he resolved them.

1. Coil freezing

   • Low airflow, dirty filter, undersized blower, or blocked drainage.

   • Check TXV bulb placement and insulation.

2. Insufficient cooling / low superheat

   • Overcharged refrigerant, oversized coil, airflow drop.

   • Adjust TXV or rebalance airflow.

3. Water blowing out of pan (blow-off)

   • Too much slope, left-side installation without blow-off bracket, high airflow.

   • Use blow-off bracket or reduce slope.

4. Drain clogging / overflow

   • Primary drain blocked.

   • Clear drain, check trap configuration, use secondary drain.

5. Refrigerant leak after brazing

   • Weak brazed joint, omitted purge, or damaged tube.

   • Repair the joint, re-purge, re-evacuate.

6. Coil sweating in humid spaces

   • Poor or missing insulation around coil casing or lines.

   • Install vapor barrier insulation around cabinet and lines.

---

🧼 8. Post-Installation Maintenance Tips

Keep your coil running long and strong by following Mike’s regular care schedule:

• Clean the coil periodically (use mild coil cleaner, rinse thoroughly).

• Check and clean condensate drain lines every season.

• Inspect and re-insulate the suction line or bulb insulation if needed.

• Replace air filters regularly to maintain airflow.

• Monitor system pressures and temperatures during seasonal startups.

• Watch for corrosion or paint wear on the cabinet; touch up as necessary.

• Document each maintenance session—this helps with warranty claims and diagnosing long-term issues.

---

✅ Final Words from Mike

By now, you’ve got a comprehensive roadmap—from unpacking to full startup—for installing a 3 Ton Horizontal Cased A-Coil with Built-In TXV. Take your time, follow the safety rules, double-check every joint and seal, and don’t rush the evacuation and charging steps.

If there's any step you feel uncertain about—especially refrigerant charging—call a certified HVAC pro to finish that part. Getting that final charge or superheat wrong can shorten compressor life badly.

In the next topic we will know more about: Coil Sizing 101: Is a 3 Ton A-Coil the Right Fit for Your Home?