Say your HVAC company produces $1.8M of adjusted EBITDA and one regional property manager represents 22% of revenue. The business is profitable. Retention is decent. The backlog looks healthy. But in the first serious PE conversation, that one account becomes the center of the underwriting discussion.
The buyer is not just asking whether the customer will stay. They are asking whether pricing can be pushed, whether the relationship lives with you personally, whether the work is recurring service or lumpy replacement projects, and what happens to the entire base case if the account is cut in half after close. That is why concentration almost never stays a footnote.
OffRamp already covers the broader valuation impact of customer concentration. This post takes the narrower PE lens: the thresholds that trigger diligence, how recurring service offsets risk, how the multiple gets re-traded, and what HVAC owners can do before going to market.
1. The Concentration Levels That Trigger PE Diligence
PE buyers usually sort concentration into three buckets. The first is not fatal, but it creates work. The second usually moves the multiple. The third starts to change the structure of the deal itself.
| Exposure | PE Interpretation | Typical Next Question |
|---|---|---|
| One customer above 10% | Flagged in diligence | Is this contract-based recurring service or project revenue? |
| One customer at 15%–20% | Real underwriting issue | Who owns the relationship and what does the renewal history look like? |
| One customer above 20% | Likely multiple pressure | What happens to EBITDA if this account shrinks after close? |
| One customer above 30% | Deal-structure concern | Do we need an earnout, holdback, or seller retention covenant? |
| Top 5 customers above 50% | Structural concentration | Is this actually a diversified platform or an account cluster? |
In residential-heavy HVAC businesses, concentration is often naturally lower because the revenue base is fragmented. In commercial HVAC, concentration shows up more often because a few large property groups, industrial sites, municipalities, or multi-site retail customers can make up a meaningful share of annual work. Buyers know that. They do not expect every commercial contractor to have zero concentration. But they do expect a clear explanation for why the revenue is durable.
What gets asked immediately
PE buyers usually want trailing 24- to 36-month revenue by customer, contract terms, gross margin by account, and a clear answer to whether the relationship belongs to the company or to the owner.
2. Why Recurring Service Offsets Risk Better Than Install Revenue
The same concentration percentage can mean very different things to a PE buyer depending on the underlying revenue. A 17% customer tied to recurring HVAC service across 40 rooftops is not underwritten the same way as a 17% customer tied to sporadic replacement projects.
Lower-risk concentration
Recurring service account
- 12- to 36-month agreement or strong renewal history
- Multiple sites, multiple contacts, dispatch history in software
- High attach rate to repairs and replacement opportunities
- Relationship owned by service manager or account team, not just founder
Higher-risk concentration
Project-driven account
- Work awarded job by job with no locked service term
- Revenue spikes tied to capex timing or one estimator relationship
- Margin compression risk if the customer negotiates aggressively
- Limited proof the account survives an owner transition
This is where a strong service agreement base helps. Recurring service does not eliminate concentration, but it gives PE buyers something they can model: renewal rate, contract margin, ticket history, and route density. That is a better answer than saying, “They have always called us when they need something.”
Buyers are also looking for evidence that concentrated customers are part of a repeatable commercial service motion rather than isolated hero accounts. If your biggest customer behaves like a template for winning and retaining similar accounts, the concentration looks more like an expandable capability. If it looks like a one-off relationship held together by the founder's cell phone, it gets discounted.
3. A Concrete Example of How Concentration Moves the Multiple
Consider two HVAC businesses, both with $1.8M of adjusted EBITDA, a healthy technician base, and comparable geography.
Company A
Diversified customer base
Company B
One customer at 22% of revenue
That 0.7x turn difference is worth $1.26M on the same EBITDA. In real deals, the buyer may not say, “We are applying a concentration discount.” They may phrase it as lower confidence in customer durability, a need for a retention-based earnout, or a different view of your normalized forward cash flow. The math lands in the same place.
The nuance buyers care about
If Company B could show that the 22% customer was on a three-year service agreement with site-level contacts, documented renewal behavior, and recurring gross margin consistency, the multiple penalty might shrink from 0.7x to 0.3x or 0.4x. Same concentration. Better revenue quality.
Run the math on your own business
If your likely multiple changed by 0.5x because of concentration, what would that do to your enterprise value? Use the calculator first, then pressure-test the concentration story before you start a process.
Three minutes. No email gate. Useful even if you are 12 months away from market.
Run the Calculator4. How HVAC Owners Can De-Risk Concentration Before Going to Market
The best time to address concentration is before the CIM is written, not after the LOI arrives. Buyers give more credit to a risk that has been intentionally reduced over 12 months than to a seller promise that it will get fixed after close.
- 1
Build a customer concentration schedule now
Pull trailing 36-month revenue by customer, including gross margin, contract term, service line mix, and the primary internal relationship owner. PE buyers will ask for this in diligence anyway. If you do not already have it, that is the first process problem to solve.
- 2
Convert large accounts from reactive work to contracted service
Buyers trust repeatable service revenue more than episodic install or emergency work. If your top accounts are currently buying ad hoc, move them toward preventive maintenance, inspection programs, and multi-site service terms that create documented renewal behavior.
- 3
Move key relationships off the founder's phone
Introduce a service manager, operations leader, or account manager into the relationship before sale. The goal is not to disappear. The goal is to prove continuity. Owner dependence and customer concentration compound each other in PE underwriting.
- 4
Add fragmented residential or light-commercial service volume
Even if commercial is your core, PE likes seeing a broader base of recurring customers underneath the largest accounts. A thicker maintenance book lowers the practical dependency on any one customer and improves the mix story at the same time.
- 5
Show the de-risking trend in the marketing materials
Buyers give credit for progress they can see. If your top customer fell from 28% to 18% over 18 months while recurring service rose from 14% to 31% of revenue, that trend belongs in the story you tell. It shows active management, not passive exposure.
This work overlaps directly with reducing owner dependence and building a stronger recurring revenue mix. Buyers look at all three together.
5. What Happens If You Go to Market With Concentration Still There
Sometimes the revenue is simply too concentrated to fix before sale. That does not mean the business is unsellable. It means the buyer will probably push the risk somewhere else in the deal.
The usual PE responses
Lower headline multiple
The cleanest buyer response. They simply pay less upfront because the risk sits in the base case.
Retention-based earnout
Part of the purchase price gets paid only if the concentrated account stays and performs after close.
Escrow or holdback
Cash is withheld for 12–24 months to cover the risk that the account churns or contracts materially.
Seller transition requirement
The buyer asks the owner to stay engaged longer to bridge the relationship risk.
Customer-call diligence before close
In some situations buyers want direct comfort from the customer or stronger evidence that assignment and continuity are secure.
This is why concentration should be discussed before you start negotiating the LOI, not after. Once the buyer frames the risk in their model, they will protect themselves somewhere. Your leverage is highest when you can offer evidence that the exposure is understood, documented, and partly de-risked already.
For HVAC owners, the practical goal is not perfection. It is credibility. If your concentration is real but the contracts are documented, the service revenue is repeatable, the relationships are institutionalized, and the trend is improving, PE buyers can still get comfortable. If the exposure is large and the story is loose, the discount will be real.
Frequently Asked Questions
What level of customer concentration usually triggers PE diligence questions?
In HVAC deals, a single customer above 10% of revenue typically gets flagged immediately. Once one account reaches 15%–20%, buyers usually want contract detail, retention history, who owns the relationship, and whether the revenue is recurring service or project-based install work.
Does recurring service revenue offset concentration risk?
Yes, but it does not erase it. A concentrated customer tied to a documented multi-site service agreement with renewal history is viewed very differently from a concentrated customer tied to one-off projects or an owner handshake. Recurring service can reduce the discount, but buyers still underwrite the exposure.
Can I still sell if one commercial customer is over 20% of revenue?
Usually yes, but expect a lower multiple, more diligence, and potentially deal-structure protections such as an earnout, escrow holdback, or retention covenant tied to that account. The best outcomes happen when sellers address the issue 12–24 months before going to market.
OffRamp is a free valuation tool for HVAC business owners. We don't sell your information, represent buyers, or work on commission. The calculator and reports are educational tools — always consult a licensed M&A advisor before entering a sale process.