Between Panels and Practice: The Craft of Installation
Installing an HVAC system isn’t just a checklist—it’s choreography. Multiple trades, tight spaces, unforgiving codes, and heat that doesn’t wait for your mistakes. Whether you’re hoisting duct or leveling a condenser, the job is a test of discipline and detail.
Three Crafts, One Symphony
Air-conditioning installation is a team sport. The key players:
- Sheet Metal Workers: The sculptors of airflow, building duct systems that deliver comfort and efficiency.
- Electricians: The nerve system installers, wiring power and controls with precision.
- Pipefitters or Refrigeration Techs: The bloodline engineers, brazing, charging, and insulating refrigerant lines to complete the loop.
Three Common Duct System Installations
- Metal Duct Systems: Long runs of galvanized steel or aluminum, strong and durable, but time-consuming to install.
- Ductboard Systems: Fiberglass boards scored and folded into rectangular channels—lighter, quieter, and pre-insulated.
- Flexible Duct Systems: Quick to install, ideal for tight spaces, but prone to sagging and airflow loss if not supported and stretched properly.
Metal Duct Installation: Square and Round
- Rectangular Metal Duct: Assembled in sections with S-cleats, drive cleats, and sealed with mastic or foil tape. Hangs from straps or brackets.
- Round Metal Duct: Spiral or snap-lock, joined with sheet metal screws, sealed, and supported with saddle hangers.
Why Insulate or Line Metal Ducts?
- Insulation prevents energy loss and condensation.
- Internal lining reduces noise and absorbs moisture, especially in return ducts.
Ductboard and Flex: The Lighter Touch
- Ductboard: Cut with a knife, folded into shape, stapled, and sealed with tape. Less durable than metal but easier to fabricate on-site.
- Flexible Duct: Pulled tight, cut to length, attached to collars, and secured with zip ties and mastic.
Voltage Range Calculation
Before firing up the system, calculate the acceptable voltage range:
- Use: Rated voltage ± 10%.
- Example: If the unit calls for 230V, the range is 207V to 253V.
- Check voltage under load to confirm adequacy.
Package Unit Installation: Best Practices
- Level the pad. Flash the curb. Connect the ductwork tight and insulated.
- Wire the disconnect and verify clearances.
- Seal all penetrations with roofing-grade material.
- Test static pressure and airflow.
Connections for Package Units
- Electrical: Dedicated circuits with correct wire gauge and breaker size.
- Drainage: Sloped PVC for condensate with cleanout.
- Gas line (if applicable): Tested for leaks and pressure.
Installing a Split-System: Precision Required
- Indoor Unit: Mounted level, with a clear return path and proper support.
- Outdoor Condenser: On a level pad, free of obstructions, with hurricane straps if required.
- Line Set: Shortest path, with minimal bends, properly insulated, and brazed with nitrogen.
Best Practices for Condenser Install
- Place away from dryer vents and gas meters.
- Protect from flood zones or snow drifts.
- Check line voltage, control voltage, and torque all lugs.
- Verify airflow clearance: typically 12-24 inches from walls.
Refrigeration Piping Done Right
- Use nitrogen while brazing to avoid oxidation.
- Pressure test to 300-500 psi with dry nitrogen.
- Evacuate to 500 microns or less.
- Measure superheat and subcooling before releasing to the homeowner.
Start-Up Checklist
- Confirm airflow.
- Verify voltage and amperage.
- Check refrigerant charge.
- Confirm thermostat operation.
- Test all safety switches.
- Log performance readings.
Installation isn’t just the beginning of comfort—it’s the foundation. Do it wrong, and every service call becomes your ghost. Do it right, and your name rides on every breeze that flows through that home. Between panels and practice, between curb and coil, you either build trust or callbacks. There is no in-between.