Optimizing thermal comfort in a multi-unit building while keeping energy consumption under control is a challenge we tackle every day at AirGreen. Installing a central heat pump in a residential multi-dwelling building is not just about choosing a high-performance unit. This type of project requires meticulous technical planning, a thorough understanding of the building's constraints, and above all, avoiding common pitfalls that could compromise the system’s performance.
In this article, we share our hands-on expertise by exploring the 7 most frequent pitfalls to avoid when installing a central heat pump in a multi-unit building in Montréal, Laval, Longueuil, the North Shore, and the South Shore. Through real-world examples and practical advice, discover how to ensure a long-lasting, code-compliant, and high-performance installation.
Skipping a detailed heat load analysis tailored to the building
One of the most common — and most serious — pitfalls is neglecting to perform a comprehensive heat load analysis of the building. Too often, some contractors base their recommendations solely on square footage or rough estimates. At AirGreen, we know that every building presents significant variations in insulation, orientation, window coverage, and occupancy.
In a recent project in Saint-Léonard, we installed a 5-ton Goodman central heat pump (R-410A) for an 8-unit building. Before selecting the system, our experts performed a room-by-room load calculation, which allowed us to choose a perfectly sized unit. This rigorous approach avoids oversizing (energy inefficiency, short cycling) and undersizing (chronic discomfort).
Choosing a system incompatible with the existing distribution
The second pitfall is choosing a heat pump that doesn’t work with the building’s distribution system. For example, in a building using hydronic radiators, you either need a heat pump compatible with a water loop or plan for major conversion work.
In an installation in Chomedey (Laval), a customer wanted to replace an old oil boiler with a central heat pump. Our team recommended a Bosch BOVA R-454B paired with an electric furnace, compatible with the existing forced-air system, thereby reducing transformation costs and ensuring seamless integration.
Ignoring electrical code compliance and permit requirements
Installing a central heat pump in a multi-unit building requires strict compliance with Québec’s electrical standards. A classic pitfall: overlooking the limitations of the main electrical panel’s capacity or failing to apply for the necessary municipal permits.
At AirGreen, every one of our projects is validated by a certified master electrician. In Longueuil, at a 1940s triplex, the electrical panel couldn’t support the addition of a 60,000 BTU heat pump. We therefore coordinated an upgrade to a 200-amp panel, while also handling the permit applications with the City. The result: a compliant, safe, and long-lasting project.
Underestimating the need for coordination with co-owners or tenants
In a shared building, the human factor is crucial. Installing a central heat pump in a duplex, triplex, or multi-unit building requires clear communication with residents, especially when invasive work is involved (ductwork routing, thermostat installation, etc.).
In a 6-plex in Brossard, each unit had different schedules. To minimize disruption, we split the work into two phases: first, installation of the Bosch IDS Premium outdoor unit on the roof, then the rollout of interior ductwork unit by unit, with pre-arranged time slots. This level of planning avoids conflict and ensures a smooth experience.
Neglecting duct insulation and sealing
Even the best equipment can't perform properly if the ductwork is poorly installed. A widespread pitfall is leaving ducts uninsulated in attics or unheated areas, or sealing them haphazardly.
During a job in Boisbriand, we replaced an old 4-ton central heat pump with a Fujitsu Airstage KXAH series. Upon inspecting the old system, we found major air leaks in the ducts. Our technicians partially rebuilt the duct system, adding R8 insulation and UL-181 rated mastic sealing, ensuring maximum energy efficiency.
Failing to assess outdoor unit noise levels
The noise generated by the outdoor unit is a sensitive issue, especially in dense residential zones. Installing a noisy or poorly positioned unit can result in neighbour complaints and damage the owner’s reputation.
At AirGreen, we always include a sound level analysis in our projects, especially in boroughs with strict regulations like Plateau-Mont-Royal or Rosemont. For an installation in a 5-plex in Verdun, we selected a Trane XV20i Inverter central heat pump, known for its ultra-low noise level (55 dB). The unit was installed on a vibration-dampening slab with a sound barrier, guaranteeing peace for the occupants… and the neighbours.
Overlooking eligibility for available grants
Last but not least: ignoring financial incentives from Hydro-Québec, Énergir, or the LogisVert program. Many clients miss out on financial support simply because the installation was not planned using an eligible certified unit.
That’s why at AirGreen, we guide every client through analyzing which grants they can access. In Sainte-Thérèse, a 4-unit building received a $6,816 LogisVert rebate for installing a Bosch BOVA-60 system, thanks to our help assembling the application.
A well-planned central heat pump installation is the key to lasting comfort
Avoiding these pitfalls requires not just technical expertise, but also real-world experience. At AirGreen, we provide you with a team specialized in multi-unit projects, capable of managing every aspect — from heat load calculations to installation, including permits and grant optimization.
Whether it’s a duplex in Montréal, a 6-plex in Laval, or a 12-unit building on the South Shore, we adapt every project to your building’s specific needs, ensuring steady comfort and long-term energy savings.
Trust AirGreen to turn your HVAC project into a smart, profitable, and worry-free investment.