Avoid costly pitfalls: what no company tells you about installing a commercial condensing boiler
In the commercial sector, efficient heating isn’t a luxury — it’s a strategic necessity. A condensing boiler, known for its high energy efficiency, has become an essential solution for commercial buildings across Montréal, Laval, Longueuil, the North Shore and the South Shore. However, despite their outstanding performance, these boilers can become a nightmare if poorly installed.
At AirGreen, we’ve been called in on numerous projects where the initial installation had been botched — not only reducing efficiency but also leading to costly repairs. Here are the 3 most catastrophic mistakes we see far too often… and how to avoid them.
An improperly sized condensing boiler: mistake #1
The direct impact on your heating costs
Incorrect sizing is the most common issue we see among commercial clients. An oversized boiler leads to frequent on/off cycling, shortening its lifespan and increasing energy consumption. On the other hand, an undersized boiler fails to meet the building’s heating demands, creating constant discomfort and repeated service calls.
Real case in Laval: when oversizing becomes a $15,000 mistake
One of our clients, owner of a small commercial building in Laval, had a condensing boiler installed rated at 800,000 BTU — even though his actual heating needs didn’t exceed 400,000 BTU. The result? Excessive consumption, premature wear and tear, and ultimately a complete system replacement by our team with a properly sized unit. We reduced his annual gas bill by 38%.
The AirGreen method
We always conduct a precise heat load analysis based on the building envelope, ventilation systems, average occupancy, and energy history. This rigorous calculation allows us to recommend a boiler that’s tailored to your real needs, not a one-size-fits-all solution based solely on square footage.
Poor venting configuration: a silent danger
The critical role of condensate drainage
Condensing boilers produce acidic water, which must be drained and neutralized correctly. If the venting system is poorly designed, it can lead to leaks, premature internal corrosion, or worse — a complete system shutdown in the middle of winter.
Example in Longueuil: makeshift venting = two weeks with no heat
A client in Longueuil contacted us after experiencing frequent shutdowns with his recently installed boiler. Upon inspection, we found that the condensate was draining into the sanitary line without a neutralizer, causing acid backflow and burner damage. We redesigned the entire drainage system, integrated a condensate neutralizer, and installed a pump with a backflow prevention valve.
What we do differently
At AirGreen, every installation includes:
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A piping system made of high-temperature PVC resistant to acidity.
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Installation of a condensate neutralizer to protect existing plumbing.
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Proper sloping to prevent water stagnation in the drain lines.
Neglecting hydraulic balancing: the invisible enemy
Why poor balancing kills your energy efficiency
Installers often overlook the balancing of the hydronic system — yet it’s critical to ensure even heat distribution across all areas of the building. Without it, some zones overheat while others stay cold, forcing the boiler to overcompensate.
Emergency call in Montréal: freezing offices, overworked boiler
In an office building in Montréal, management complained of freezing temperatures in certain wings, despite having a new boiler. After inspection, we discovered a complete lack of balancing valves and an uneven distribution network. Thanks to a room-by-room thermal analysis, we installed both manual and automatic balancing valves, adjusted the flow rates, and restored uniform comfort throughout.
Our AirGreen approach
Every system we install includes:
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A custom hydronic layout.
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Balancing tests at project completion with fine-tuning.
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Thermographic inspections to validate even heat distribution.
Practical tips for a successful commercial boiler project
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Don’t rely solely on price: a low quote often hides technical shortcuts.
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Ask for a certified heat load study before any sizing recommendation.
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Ensure your installer is trained in condensing technology: not all HVAC contractors are.
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Check your eligibility for grants (such as Hydro-Québec’s LogisVert program or Énergir’s incentives).
What sets AirGreen apart in commercial heating
At AirGreen, we combine technical expertise, in-depth product knowledge (Lennox, Bosch, ACD, etc.), and field experience from dozens of commercial installations across Montréal, Laval, Longueuil, the North Shore and the South Shore. We support you from thermal evaluation to after-sales service, with complete transparency at every stage.
Grants and return on investment
Condensing boilers are often eligible for significant grants, especially in the commercial sector. We help our clients:
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Obtain incentives worth several thousand dollars through Énergir or municipal programs.
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Assess their return on investment by comparing pre- and post-installation operating costs.
In conclusion
A commercial condensing boiler is a high-performance solution, but it demands precise expertise to ensure durability, efficiency, and safety. Don’t fall into the trap of rushed installations. At AirGreen, every project is a commitment to excellence.