FORESTAIT MZ R454B 2-Zone Wall-Mounted Heat Pump | Outdoor: 42000 BTU
The ForestAir MZ R454B 42 000 multi-zone heat pump heats and cools 2 rooms with a single outdoor unit. it delivers 31,000 BTU/h at −8 °C, heats down to −25 °C and qualifies for a $3,720 LogisVert grant. Installed by AirGreen in Montréal, Laval, Longueuil, the North Shore and the South Shore.
2 rooms, one outdoor unit.
Compared with the 86 multi-zone systems of 42,000 BTU we sell. Every number on this page carries its source.
The parts that make a multi-zone system.
Tap a part to learn more.
Outdoor unit
One compressor for the whole house. It supplies up to 5 heads and modulates from 6,500 to 32,000 BTU/h depending on what the rooms call for (NEEP).
Base pan heater
A heater keeps the outdoor unit’s base pan free of ice below 1 °C and during defrost (NEEP).
Refrigerant lines
One pair of lines per head.
Indoor heads
One head per room, each with its own remote and temperature. The combination is chosen in the “Zones” menu.
Control
Each zone is set separately, also from your phone.
Turn rooms on and off. Watch the power being shared.
One outdoor unit supplies every head: when several rooms call at once, they share its capacity. Pick an outdoor temperature.
Tell us your rooms. We tell you if this size is enough.
Pick the number of rooms and their size. The estimate targets a −15 °C day; it is a guide, the real calculation is done room by room at your home.
The whole series at a glance: find the box that fits you.
Each box is a product: the outdoor unit’s size, and the number of heads.
At −15 °C, it still delivers 71 % of its rated capacity.
Tap a temperature: certified capacity, efficiency and the cost of one hour of heating.
It slows down, it speeds up: the certified modulation range
Light bar: from minimum to maximum capacity. Dark mark: the rated value.
At every temperature, cheaper than baseboards.
Cost of one hour at full output, for the same heat delivered. Hydro-Québec Rate D, second tier: 11.142 ¢/kWh.
The official ratings, on the same scales as before.
SEER2, HSPF2 and EER2 come from the AHRI certification. The mark shows the median of the same-size multi-zone systems we sell.
A grant you can calculate, not guess.
The capacity at −8 °C comes from Hydro-Québec’s list of October 1, 2026. $120 per 1,000 BTU/h is the rate for ENERGY STAR cold-climate heat pumps (guide v1.10).
Where it ranks among same-size multi-zone systems.
Compared with the 86 multi-zone systems of 42,000 BTU we sell, using the LogisVert list figures. Weaknesses too, said plainly.
Against three other brands in its class.
Same rated size, other manufacturers. Pick the opponent.
One multi-zone or several wall units? Both sides, honestly.
We compare both options on your floor plan during the estimate.
What to know before installing a multi-zone system.
Dimensions, wiring and lines, drawn. Then our six steps.
The outdoor unit, dimensioned
One circuit for the whole house
Published sound levels, on one scale.
We use the outdoor figure to choose where the unit goes.
What is particular about this machine.
Only facts published by ENERGY STAR, NEEP or the manufacturer.
Every number, and where it comes from.
Each line carries its source; a line with no published value is not shown.
The manufacturer’s documentation, as PDF.
Everything we have written about this system.
A high-performance multi-zone HVAC solution designed for Quebec's climate
At AirGreen, we regularly install multi-zone systems to address a well-known reality in Montreal, Laval, Longueuil, North Shore, and South Shore: homes with several distinct spaces, each having different thermal needs. The FORESTAIR MZ R454B (42,000 BTU) wall-mounted heat pump stands out as a coherent, high-performing, and durable technical solution for these contexts.
This model is distinguished by its balance between power, energy efficiency, and installation flexibility, particularly due to its ability to power up to 5 indoor units, although it is optimized here in a 2-zone configuration.
Controlled power for residential and multi-dwelling needs
Actual capacity and performance in Quebec conditions
The FORESTAIR MZ 42,000 BTU offers a nominal cooling capacity of 42,000 BTU and maintains heating performance down to -25°C, which is essential for Quebec winters.
Here are the key data:
- Nominal power: 42,000 BTU
- Power at -8°C: 31,000 BTU
- Power at -15°C: 30,000 BTU
- Heating operation down to -25°C
- Cooling operational down to -15°C outdoors
In our installations in Boucherville and Laval, this type of system is often recommended for:
- Multi-story houses with distinct zones
- Duplexes or triplexes with thermal divisions
- Spaces with additions (extension, solarium, separate office)
An important point observed in the field: the stability of heating performance is particularly appreciated in less well-insulated buildings.
Inverter technology and advanced energy efficiency
Optimized continuous consumption
This model uses DC Inverter technology, allowing power to be adjusted in real time according to needs. The result: fewer on/off cycles, more stable temperature, and reduced consumption.
Performance indices:
- SEER2: 22.0
- HSPF2: 10.0
- EER2: 11.2
- COP: 3.50
In practice, this means:
- Significant energy savings
- Constant comfort without fluctuations
- Better compressor longevity
At AirGreen, we have observed that customers switching from a conventional electric system to this heat pump significantly reduce their energy costs from the first season.
R-454B Refrigerant: A major evolution in HVAC
Transition to a more environmentally friendly gas
The FORESTAIR MZ uses R-454B refrigerant, a newer and more ecological alternative to older gases like R-410A.
Advantages:
- Reduced global warming potential (GWP)
- Improved thermal efficiency
- Compliance with new environmental standards
For owners in Montreal and on the South Shore, this represents a choice aligned with new energy and environmental requirements.
Multi-zone flexibility: A concrete advantage in installation
Up to 5 zones possible
Even though this sheet concerns a 2-zone configuration, the outdoor unit allows for expansion up to 5 zones, making it an scalable investment.
Typical configurations we install:
- 2 x 12,000 BTU
- 9,000 + 18,000 BTU
- 12,000 + 24,000 BTU
Each indoor unit can be selected according to the specific needs of each room (bedroom, living room, basement).
Essential technical details for successful installation
Piping data and actual constraints
- Gas line: 3/8 in
- Liquid line: 1/4 in
- Max total length: 90 m (295 ft)
- Length per unit: 30 m (98 ft)
- Max elevation difference: 10 m (33 ft)
This data is crucial during installation. At AirGreen, we have already corrected several poorly planned installations by other contractors where these limits were not respected.
Dimensions and outdoor installation
- Dimensions: 42.25 x 33.63 x 18.38 in
- Weight: 79 kg (net)
- Sound level: 65 dB(A)
We generally recommend:
- Installation on a wall bracket or anti-vibration base
- Sufficient clearance for air circulation
- Strategic positioning to reduce perceived noise
AirGreen case study: installation in Longueuil (duplex)
We recently installed this heat pump in a duplex in Longueuil with:
- A 12,000 BTU unit on the ground floor
- An 18,000 BTU unit upstairs
Challenges encountered:
- Piping passage through a load-bearing wall
- Optimized drainage without a pump
- Adherence to maximum distances
Result:
- Uniform thermal comfort
- Significant reduction in indoor noise
- Customer satisfied with independent zone control
Maintenance and durability: what you need to know
A multi-zone heat pump requires rigorous maintenance to maintain its performance:
AirGreen recommendations:
- Filter cleaning every 3 months
- Annual professional maintenance
- Check pressures and gas
An important point: systems using R-454B require handling by qualified technicians, which our certified refrigeration specialists ensure.
What distinguishes AirGreen in HVAC installation
Choosing AirGreen for your HVAC installation in Montreal, Laval, Longueuil, or on the South Shore means benefiting from:
- Certified and experienced refrigeration technicians
- Personalized thermal analysis
- Installation compliant with RBQ standards
- Total price transparency
- Support for LogisVert subsidies (up to $3720)
We have installed hundreds of similar systems, and our expertise helps avoid common errors:
- Incorrect sizing
- Incorrect unit placement
- Underestimation of pipe lengths
Conclusion: A reliable, scalable heat pump adapted for Quebec
The FORESTAIR MZ R454B 42,000 BTU 2-Zone Wall-Mounted Heat Pump represents a solid choice for owners seeking a high-performing, efficient, and durable multi-zone solution.
It is distinguished by:
- Its ability to operate down to -25°C
- Its high energy efficiency
- Its installation flexibility
- Its use of R-454B
At AirGreen, we recommend this model in very specific contexts where multi-zone performance is essential.
Contact AirGreen for a personalized quote
Are you considering a multi-zone heat pump installation in Montreal, Laval, Longueuil, or on the South Shore?
Contact us today for:
- A free evaluation
- A recommendation tailored to your property
- A clear and detailed estimate
Our team supports you from system selection to complete installation.
Warranty: 10 years on the compressor, 10 years on parts and 6 years on labor, straight from the distributor.
What people ask us about multi-zone systems.
Can I heat one room and cool another at the same time?
No. On a multi-zone system like this one, every head works in the same mode, heating or cooling. Each room still keeps its own set temperature.
What happens when every room calls for heat?
They share the outdoor unit’s capacity: 31,000 BTU/h at −8 °C, 30,000 at −15 °C.
How many heads can I connect?
Up to 5 on this outdoor unit. This product is configured for 2 heads.
How much is the LogisVert grant?
$3,720 according to Hydro-Québec’s list of October 1, 2026. The grant never exceeds 100 % of the cost before taxes; apply within 9 months of installation.
Is it ENERGY STAR certified?
Yes, cold climate, ID 4529626. It also meets the ENERGY STAR Most Efficient criteria, according to the ENERGY STAR database.
Down to what temperature does it heat?
Down to −25 °C.
Is it noisy?
Indoors, the reference head goes down to 30 dB(A). Outdoors, 65 dB(A): we place the unit away from bedroom windows.
Why a multi-zone instead of several wall units?
One outdoor unit on the wall and one circuit. In return, the rooms share the capacity, and if the outdoor unit stops, every zone stops.
What does the warranty cover?
Our sheet lists 10 years on the compressor and 10 years on parts. AirGreen extended warranty: possible.
A multi-zone system is planned room by room. At your home.
We measure every room, draw the line route and choose the right head for each zone. The on-site estimate is free and the quote arrives within 24 h.