How to measure a replacement coil for your A/C system

Measuring Replacement HVAC Coils

How to measure a replacement coil for your A/C system

  • Learn the critical measurements needed for accurate coil replacement.
  • Discover why DIY coil measurements often lead to costly mistakes.
  • Get expert insights into how KCL ensures a perfect match — no retrofits, no headaches.

When your air conditioning system starts losing performance, making odd noises, or leaking refrigerant, chances are the coil needs attention. Replacing it isn’t as simple as ordering a new part — especially in commercial or institutional buildings where systems are custom-built or decades old.

If you’re considering replacing a coil in your A/C unit, accurate measurement is everything. And if you’re in Ontario, KCL can handle it for you — ensuring a perfect fit, the first time.

Let’s take a look at what goes into measuring an A/C replacement coil.


What You Need to Measure for an A/C Coil Replacement

1. Coil Dimensions

  • Finned Height & Length
    Measure only the active fin area — not the casing or mounting flanges.
  • Casing Height, Length & Depth
    Include the full metal frame that houses the coil. Casing depth corresponds to how many tube rows are stacked in the direction of airflow.

2. Number of Rows & Tube Configuration

  • Rows
    Count the rows of tubes front to back. More rows = deeper coil = greater capacity.
  • Tube Diameter
    Standard sizes include 3/8″, 1/2″, and 5/8″. Matching this exactly is critical for flow rates.
  • Tube Pattern
    The stagger (e.g., 60°, 90°) and spacing affects airflow and performance.

3. Fin Details

  • Fins per Inch (FPI)
    More fins increase surface area — and heat exchange — but can also affect static pressure.
  • Fin Type/Material
    Aluminum is common, but epoxy-coated or copper fins are used in harsh environments.

4. Connection Information

  • Connection Size & Type
    Measure outer diameter and note whether it’s sweat, threaded, or flange.
  • Connection Location
    Use the coil’s casing as a reference point and record how far each connection is from the top or bottom edge.

5. Airflow Direction

Is it vertical (up/down) or horizontal (side-to-side)? This affects how the coil is mounted and how it performs.


Why DIY Measurements Can Be Risky

Even the most experienced contractors can make honest mistakes when measuring coils — especially when dealing with tight clearances or aging equipment.

Common issues from DIY measurements:

  • Coils that don’t fit the housing
  • Mismatched connections
  • Airflow problems from wrong row or fin configurations
  • Delays and added costs due to modifications on-site

Bottom line? An incorrectly measured coil can bring your entire system to a halt.


Let KCL Handle the Measuring

We’ve seen every kind of A/C setup — from rooftop units in office towers to built-in systems in shopping centres and schools. Our team provides on-site measurement services to take the guesswork out of the process.

Here’s what we deliver:

  • Accurate field measurements
  • Custom-engineered replacements that match original specs
  • Direct-from-manufacturer pricing with no middlemen

We don’t just sell coils. We make sure the replacement works without any retrofit — saving you time, labour, and frustration.


If your A/C system is due for a coil replacement, don’t measure it yourself — measure it right.

Contact KCL today to schedule a professional coil assessment and get a solution that fits the first time.