Understanding the Link Between Indoor Humidity and Wall-Mounted Heat Pumps in Québec Homes
In many homes across Greater Montréal, from Laval to Longueuil, including the North Shore and South Shore, excessive humidity remains a central issue affecting both comfort and health. Too often, this issue is misunderstood or poorly addressed. At AirGreen, as recognized experts in wall-mounted heat pump installation, we regularly meet clients who wonder whether a wall-mounted heat pump can manage or worsen humidity problems. In this article, we uncover the technical truth, while sharing on-site observations and practical advice.
What’s the Real Cause of Excessive Humidity in a Home?
Before we can talk solutions, we must first understand the problem. Excessive humidity can come from several sources: poor insulation, inadequate ventilation, water infiltration, lifestyle habits (e.g., long showers, cooking without an active range hood), or the absence of an effective dehumidification system.
In well-insulated homes—especially modern or renovated constructions—humidity tends to build up more easily, particularly during the winter when windows stay closed and natural ventilation is non-existent. The result: window condensation, musty odors, discomfort, and even mold growth.
Wall-Mounted Heat Pump: Its Role and Limits in Managing Humidity
A wall-mounted heat pump, like the models we frequently install across Montréal and surrounding areas (Fujitsu KZAH, Gree Lomo, Sharp ZU1, etc.), is primarily designed to heat and cool the air. But what about humidity?
Yes—but Only in Cooling Mode
In cooling mode, a wall-mounted heat pump naturally extracts some moisture from the air. By cooling the air, it causes condensation on its indoor coil, which helps to reduce relative humidity. However, this dehumidification capacity depends on many factors:
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Indoor temperature
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Initial relative humidity level
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Fan speed
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Duration of system operation
But be careful: in heating mode, the effect is zero. The warm air produced by the heat pump does not remove moisture. Worse, it can actually dry the air... if humidity is already low, or contribute to a clammy feeling if the humidity is high—without truly eliminating it.
Case Study: Fujitsu KZAH Installation in Laval with a Humidity Issue
One of our clients, a homeowner in Laval, contacted us for the installation of a Fujitsu KZAH 12,000 BTU wall-mounted heat pump. Their main concern: reducing persistent humidity in the basement, especially in summer. After evaluation, our team found that the issue wasn’t lack of cooling, but rather the absence of proper mechanical ventilation.
Our solution was to install the heat pump in the main living area, paired with a heat recovery ventilation system (HRV). The result: optimal comfort, a significant reduction in humidity, and controlled energy consumption. We also educated the client on the importance of annual HVAC maintenance, especially cleaning the condensation drain.
Do You Need a Dehumidifier Alongside a Wall-Mounted Heat Pump?
Yes, in many cases. A wall-mounted heat pump is not a substitute for a dedicated dehumidifier, especially in areas like the basement, laundry room, or rooms without direct air conditioning. Our technicians often recommend adding a portable or centralized dehumidifier when humidity levels exceed 60% RH (relative humidity).
Common Mistakes We See Among Clients
Here are some common mistakes our teams find during visits in Montréal, the South Shore, and the North Shore:
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Believing a heat pump solves all air quality problems
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Installing the wall unit too high in a poorly ventilated room
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Neglecting to clean the condensation drain, causing leaks
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Failing to measure humidity levels with a hygrometer
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Installing an oversized heat pump that cycles too quickly to effectively dehumidify
Best Practices for Managing Humidity with a Wall-Mounted Heat Pump
1. Proper Unit Sizing
A properly sized heat pump (according to each room’s required BTUs) ensures better balance between heating, cooling, and dehumidification. At AirGreen, we always conduct a thorough calculation based on surface area, exposure, and insulation.
2. Smart Programming
Use the Dry mode feature when available, especially in summer, to prioritize dehumidification without overly cooling the space.
3. Regular Maintenance
A full HVAC maintenance check should be done once a year: filter cleaning, drain inspection, cleaning of the indoor and outdoor coils, etc. This optimizes performance and prevents humidity-related breakdowns.
4. Supplement with Mechanical Solutions
Installing an HRV (heat recovery ventilator) or an independent dehumidifier can transform a partial HVAC system into a complete air treatment solution.
The AirGreen Approach: Diagnosis, Installation, and Tailored Solutions
At AirGreen, we don’t just install machines: we thoroughly analyze each case. Every wall-mounted heat pump installation is preceded by a complete diagnosis, including humidity evaluation, lifestyle habits, and building-specific conditions.
Thanks to our expertise, we provide balanced solutions, often hybrid: heat pump + ventilation + dehumidification. We have successfully installed dozens of Fujitsu, Gree, Sharp, or Bosch wall-mounted systems across Montréal, Laval, and both shores, effectively resolving real comfort issues.
In Conclusion: Don’t Be Fooled by Half-Truths
A wall-mounted heat pump can help reduce humidity—but it’s not enough on its own. It needs to be part of a comprehensive indoor air treatment strategy, carefully planned and adapted to your specific situation.
At AirGreen, we put our know-how at the service of your comfort. Whether you’re in Montréal, Laval, Longueuil, the North Shore or the South Shore, we offer an honest, technical, and personalized approach. Don’t hesitate to contact us for a full evaluation of your situation.