Churn
How many clients an agency loses a year, and why it is the most honest number they have.
What it means
The rate at which clients leave. Usually quoted as monthly or annual retention, occasionally as average tenure. It is the one metric an agency cannot improve through better reporting, because it is measured by other people voting with their invoices.
It is also almost never published, which makes the ones who do publish it worth noticing regardless of the figure.
Why it matters in HVAC
Seasonal cancellation makes the raw figure lumpy. Shops leave in the shoulder months, so an agency quoting a single annual number is averaging across a pattern rather than describing a steady state.
Average tenure is the more useful shape in this trade. An agency whose typical HVAC client stays four years has survived four full seasons with them, which is a stronger claim than any month-by-month retention percentage.
How to check it
Ask for average client tenure in your trade specifically, and ask how many HVAC clients they have lost in the last twelve months. The second question gets a more honest answer than the first because it is harder to average.
The only published retention figure here
Plumbing & HVAC SEO publishes 96% or better average monthly client retention on its case studies page, alongside 600 contractors served and ten recorded client interviews.
Monthly retention needs converting before it means anything. Ninety-six percent a month compounds to roughly sixty-one percent across a year, which implies a typical client relationship a little over two years long. That is a respectable number for the trade and it is a very different impression from the one the raw ninety-six gives.
They also publish a seven-year client, Cardinal Heating, Cooling, Plumbing and Electric in Sun Prairie. A long named relationship carries more weight than a retention percentage, because you can ring it.