Cost cap
A bid strategy that asks Meta to keep your average cost per result around a stated figure.
It is an average rather than a ceiling. Individual results can cost more or less; Meta aims for the number across the ad set, and will slow delivery rather than exceed it consistently.
Why it matters for HVAC
It is the strategy that maps most directly onto how a contractor thinks. You know roughly what a booked job is worth and what you can pay to get one, so expressing that as a number is natural.
The danger is setting it from cost per lead when you meant cost per booked job. A cap that produces cheap leads nobody books is doing exactly what it was told.
How it is measured
Actual average cost per result against the cap, and delivery against budget. Set it too low and the ad set starves, which also pushes it toward learning limited, so a cap that is too tight damages the account twice.
A worked example
A contractor books about one in eight Meta leads and a booked job is worth $2,400 with roughly $700 of gross margin. Paying up to $300 per booked job implies a cost cap near $37 per lead. Set instead at $20 because that felt affordable, the ad set spends a quarter of its budget and never leaves learning.
These figures are invented to show the arithmetic. They describe no real business.
Where this is demonstrated
The Advantage+ against manual pillar scores every listed agency on what they document here, and gives you the questions that tell you which one you are being sold.