Mastering indoor humidity in Montreal with an efficient, customized multizone heat pump system
In an urban environment like Montreal, where the seasons swing dramatically from humid heat to dry cold, managing indoor humidity is a constant challenge for many homeowners. Too much humidity can lead to mold, respiratory issues, or even structural damage. Too little, and winter comfort takes a serious hit. At AirGreen, we firmly believe that the smart, long-term solution to this issue lies in a tailored HVAC installation, especially through the installation of a multizone heat pump.
Why humidity is a major concern in Montreal
Montreal’s climate—with harsh winters and sticky summers—puts significant pressure on heating and cooling systems. In poorly ventilated or under-insulated homes, humidity quickly builds up, particularly in areas like basements, bathrooms, or kitchens. Portable dehumidifiers offer a temporary fix, but they don’t address the core issue: managing air across the entire home.
The multizone heat pump: a technical response to a practical need
Unlike standard wall-mounted systems, a multizone heat pump allows you to independently control temperature and humidity across several areas of the home. Each indoor unit connects to a single outdoor unit, offering maximum flexibility and improved energy efficiency.
This system is ideal for medium to large-sized homes, duplexes, triplexes, or commercial offices with varying comfort needs across rooms or floors.
How a multizone heat pump helps control humidity
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Independent temperature and humidity control in each zone: A south-facing bedroom can be managed separately from a typically damp basement.
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Continuous dehumidification in cooling mode: Unlike window or portable units, multizone heat pumps actively dehumidify air while cooling.
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Extended operation at low speed: Thanks to inverter technology, units run longer at low power, improving air circulation and humidity regulation.
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Prevents condensation and mold: By keeping relative humidity between 40–50%, these systems stop dew point formation on cold surfaces.
Case study: Multizone heat pump installation in a Plateau-Mont-Royal triplex
Recently, we were contacted by a triplex owner on Saint-Denis Street in Montreal, struggling with serious humidity issues in the basement and rear bedrooms, while also looking to efficiently cool the entire building.
The challenges:
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Century-old building with partial insulation.
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Limited access for the outdoor unit.
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Three zones with distinct heating and cooling needs.
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Recurring mold issues despite using portable dehumidifiers.
The AirGreen solution:
We recommended the installation of a Fujitsu AIRSTAGE multizone system (model Fujitsu AOU36RLXFZ with three indoor units Fujitsu ASYG09KMTB, each 9,000 BTU), paired with smart thermostats for precise zone control. With our HVAC expertise, we mounted the outdoor unit on an anti-vibration wall bracket, fully insulated the refrigerant lines, even in areas only accessible through a crawl space.
Two weeks later, the results were clear:
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Relative humidity dropped from 68% to 48%.
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Gradual disappearance of moldy odors.
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Lower electricity use compared to previous portable systems.
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Enhanced comfort in every zone without relying on open windows or constant mechanical ventilation.
Other benefits of multizone heat pumps for Montreal homeowners
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Eligibility for LogisVert grants: Several models like the Gree Multi+ Ultra or Daikin MXS qualify for financial incentives from Hydro-Québec.
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Reduced heating costs: With high seasonal efficiency ratings (up to 20 SEER and 10 HSPF), multizone heat pumps significantly cut energy bills year-round.
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Aesthetic, discreet installation: Our certified AirGreen technicians use heat-resistant line hide covers tailored to each building’s architecture—whether Westmount stonework or Old Montreal brick.
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Smart control: Most systems are compatible with Google Home, Alexa, or a mobile app, offering real-time humidity and temperature management.
What to consider before installing a multizone heat pump
1. Proper system sizing:
An oversized or unbalanced system can cause uneven humidity and temperature. At AirGreen, we always perform a detailed room-by-room heat load calculation before making any recommendations.
2. Strategic unit placement:
Units should not be installed in closed-off or poorly ventilated areas. Our installers ensure each unit enjoys optimal air circulation, even in complex areas like mezzanines or partitioned basements.
3. Electrical system readiness:
Some multizone systems may require upgrades to the electrical panel. Our team works with certified electricians to guarantee full compliance with Quebec’s building code.
Why trust AirGreen for your HVAC project in Montreal?
We’re not just installers — we’re your long-term comfort partners. Every project is carried out with meticulous attention to detail, full pricing transparency, and a commitment to energy efficiency.
Our clients from neighborhoods like Rosemont, Ahuntsic, Verdun, Laval-des-Rapides, and Brossard recommend us for our precision, responsive after-sales service, and ability to solve humidity issues for good.
Conclusion: A healthy, comfortable home all year long
A properly installed multizone heat pump is more than just a heating and cooling system: it’s a true humidity control tool, offering personalized comfort and energy savings. At AirGreen, we combine our HVAC expertise, technical know-how, and strong service ethic to deliver each customer a customized, durable, and energy-efficient solution, across Montreal, Laval, Longueuil, North Shore, and South Shore.