Common mistakes to avoid when installing a multizone heat pump system in Quebec
At AirGreen, we understand that a multizone heat pump installation is a strategic investment to improve thermal comfort and energy efficiency in your home or commercial building. However, despite all the advantages these systems offer, many mistakes can be made during selection, planning, or installation. These often-overlooked errors can lead to cost overruns, reduced performance, or significantly shorter system lifespan.
Backed by our experience with projects in Montréal, Laval, Longueuil, the North Shore and the South Shore, today we’re sharing five common pitfalls we’ve encountered in the field, along with our practical advice to avoid them.
1. Underestimating the complexity of designing a multizone system
Improper sizing: a common issue
Unlike a standard single-zone wall-mounted unit, a multizone heat pump connects multiple indoor units to a single outdoor unit. This requires precise design. Too often, installers or homeowners choose a system without considering the BTU sizing for each room, leading to an imbalance between the outdoor unit’s capacity and the actual thermal needs of each zone.
Real-life example from AirGreen:
In Laval, we recently took over a project in a duplex where a competitor had installed a 36,000 BTU system with five indoor heads. The result: some rooms stayed cold in winter because the system was overstretched. We re-engineered the layout with a precise heat load calculation, replaced the outdoor unit with a 42,000 BTU model from Fujitsu, and optimized the refrigerant line lengths.
2. Overlooking the layout and placement of indoor units
Poor planning impacts efficiency
The placement of indoor wall units needs to be strategic. If a unit is installed too close to the ceiling, a corner, or a heat source (direct sunlight, appliances), it can prevent even air distribution.
Our approach at AirGreen:
During an installation in Brossard, on the South Shore, we advised the client to reposition two indoor units that were initially planned for impractical locations. Using a 3D layout simulation, we showed that an alternative placement would deliver better energy performance and greater comfort throughout the rooms, especially in an upstairs bedroom.
3. Choosing a model unsuited for harsh Quebec winters
Beware of misleading product claims
Not all multizone systems are designed to perform at -25 °C. Many budget or imported models can’t handle Quebec’s deep freeze. This is a frequent mistake we’re called in to fix.
Our recommendations:
We recommend trusted brands such as Fujitsu, Gree, Tosot, Bosch, or Goodman, with product lines certified Energy Star and built to maintain heating capacity down to -30 °C. For instance, the Fujitsu Airstage K Multi or the Gree Multi Ultra Heat are two solid choices we often install across Montréal and the North Shore.
4. Poor planning of piping lengths and system connections
Technical errors that lead to costly issues
The proper operation of a multizone system also depends on strictly adhering to the maximum refrigerant line lengths between the outdoor unit and each indoor head. Excessive distance or poor elevation planning can cause pressure loss, refrigerant leaks, or ineffective operation.
Corrected installation in Longueuil:
One client attempted a partial DIY installation. The result: unstable gas pressure, and two indoor heads out of service after winter. Our team brought everything back up to code: removed the old lines, installed a custom insulated copper piping network, performed nitrogen pressure testing, vacuum tests, then recharged with R-410A refrigerant according to manufacturer specifications.
5. Overlooking available grants for multizone systems
A missed opportunity that can cost thousands
Did you know a multizone system can qualify for several financial incentive programs, such as Hydro-Québec’s LogisVert program or the Chauffez Vert rebates? Many clients are unaware of these incentives and end up overpaying.
What we do at AirGreen:
We guide every client through the grant eligibility process, taking care of the required documentation. In Sainte-Thérèse, on the North Shore, our team recently secured a $3,500 rebate for a client who chose a Bosch BOVA multizone heat pump. It’s added value that few competitors offer with the same level of thoroughness.
Don’t neglect ongoing maintenance
A multizone heat pump requires regular maintenance to perform optimally. This includes:
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Cleaning filters every 4 to 6 weeks.
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A professional HVAC maintenance check annually, including coil cleaning, gas pressure check, and electrical connection inspection.
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Inspecting outdoor piping before winter.
AirGreen offers custom maintenance packages tailored to your specific installation type.
Why choose AirGreen for your multizone heat pump?
Field experience, technical expertise, and turnkey service
With hundreds of successful installations in Montréal, Laval, Longueuil, the North Shore and the South Shore, we’ve developed a unique level of expertise in multizone HVAC solutions. Our certified technicians arrive with professional equipment, exceptional attention to detail, and the ability to solve unforeseen issues quickly.
Our clients value our transparency, adaptability, and the quality of our after-sales service. We don’t just sell a product — we build lasting trust-based relationships.
Conclusion: A well-managed project avoids major headaches
Multizone heat pump installation is not a project to take lightly. Every detail matters: from choosing the right model, to configuring indoor units, to respecting all technical standards. By avoiding the five pitfalls we’ve outlined, you’ll maximize your return on investment and enjoy optimal comfort, year-round.
At AirGreen, we do more than just install HVAC systems. We support our clients with precision, transparency, and expert care.