Installation of a Hitachi airHome Multi dual-zone, multi-zone heat pump on a balcony in Saint-Lambert

A compact installation designed to preserve the use of a residential balcony

Installing a multi-zone heat pump on a narrow balcony requires much more than simply finding an available spot. Airflow around the outdoor unit, surface strength, future access for maintenance, refrigerant line routing, drainage, and, above all, the occupants’ daily use of the balcony must all be taken into account.

For this installation in Saint-Lambert, our AirGreen team had to integrate a Hitachi airHome Multi dual-zone heat pump into an already developed outdoor space. The wooden balcony was bordered by a decorative metal railing and furnished with patio furniture. The goal was therefore to install an efficient heating and cooling system without turning the balcony into a cluttered mechanical area.

The selected solution uses a Hitachi airHome Multi outdoor unit installed on a raised floor stand. This setup stabilizes the unit, lifts it off the balcony surface, and facilitates airflow beneath the equipment. The result is a clean, organized installation suited to the architectural constraints commonly found in plexes, condominiums, and homes in Saint-Lambert, Longueuil, and denser areas of the South Shore.

Why a dual-zone system was the right fit for this residence

A multi-zone heat pump can power several indoor units from a single outdoor unit. In this residence, two separate zones needed to be heated and cooled without adding two condensers to the balcony.

The dual-zone configuration offers several practical benefits:

• a single visible outdoor unit;
• two indoor units that can be adjusted separately;
• a smaller outdoor footprint;
• a temperature better suited to each room’s use;
• fewer ducts and outdoor connections than with two independent systems;
• more flexible comfort management between floors or different living areas.

In the Hitachi airHome Multi range presented by the manufacturer, the two-indoor-unit configuration corresponds to the RAM-G18N2HAA outdoor unit, with a rated cooling capacity of 18,000 BTU/h and a rated heating capacity of 22,000 BTU/h. The complete range also includes three-, four-, and five-zone configurations, up to 42,000 BTU/h.

The final choice of indoor capacity must never be based solely on the number of rooms. At AirGreen, we also consider the floor area, insulation, window orientation, solar gains, ceiling height, and the natural airflow between spaces.

A narrow balcony that required precise planning

The photograph of this installation clearly shows one of the project’s main challenges: the outdoor unit had to be placed in a space bounded by the railing, the building wall, and the outdoor furniture.

We organized the installation to preserve:

• usable passage around the unit;
• reasonable access to the electrical components;
• clearance in front of the surfaces required for heat exchange;
• an orderly path for the lines;
• a balcony surface that is as functional as possible.

The heat pump’s placement must never be improvised. An outdoor unit that is too close to a wall, awning, panel, or piece of furniture may recirculate its own air and lose efficiency. On a balcony, this issue becomes even more important, as railings and surrounding objects can restrict airflow.

In this case, the rear side of the coil remains visible and accessible. Air can reach the heat exchanger without a solid partition being placed directly against the unit. The chair and small table were also left at a reasonable distance from the unit, allowing the owner to continue using the balcony while keeping in mind that no object should block the equipment.

A raised support suitable for installation on a wooden terrace

The Hitachi unit was placed on a metal floor stand rather than directly on the balcony boards. This method serves several essential purposes.

Weight distribution

The support creates a stable base and distributes the load across several points of contact. This precaution is particularly important on a wooden terrace, where the boards may flex or age differently depending on their exposure to water.

Vibration reduction

Anti-vibration mounts are visible between the unit and the support. They help limit the transmission of vibrations to the balcony and the building structure. For an installation near a bedroom or living room, this attention to detail significantly improves acoustic comfort.

Clearance beneath the unit

The elevation leaves open space beneath the heat pump. This facilitates balcony cleaning, limits prolonged contact with moisture, and improves access for certain technical interventions.

Protection Against Accumulation

Although a balcony is often less exposed to snow than a ground-level yard, accumulations can form during the winter. A slightly elevated unit is better protected from wet snow, ice, and plant debris.

Grouped Lines Without Cluttering the Space

To the left of the outdoor unit, the refrigerant lines and cables are grouped together and secured against the railing. This arrangement prevents the connections from running freely across the floor, where they could become an obstruction or be damaged by moving furniture.

The routing of the lines is a key consideration in a multizone HVAC installation. Each indoor unit has its own pair of refrigerant lines and communication wiring. A route must therefore be planned that remains:

• protected;
• accessible;
• properly insulated;
• watertight against water infiltration;
• compatible with the permitted bend radii;
• discreet enough to preserve the building’s appearance.

For the Hitachi dual-zone configuration, the manufacturer’s technical table specifies two 1/4 in. liquid connections and two 3/8 in. gas connections at the outdoor unit. The maximum total piping length specified for this configuration is 165 ft, with a maximum of 82 ft between an indoor unit and the outdoor unit.

These limits provide good flexibility in buildings where the two indoor units are not located directly behind the balcony. However, they do not replace careful route planning. The more bends, level changes, or outdoor sections an installation includes, the more precise the preparation must be.

An Accessible and Secure Power Supply

An electrical box is installed in the immediate vicinity of the unit. This arrangement makes it possible to disconnect the power near the equipment during maintenance or repairs.

For the dual-zone RAM-G18N2HAA model, the technical documentation specifies a nominal power supply of 208-230 V, single-phase, 60 Hz, a minimum circuit ampacity of 16 A, and maximum overcurrent protection of 25 A.

The actual sizing of the wiring, circuit breaker, and disconnect switch must always comply with the nameplate of the installed equipment, applicable electrical requirements, and the building’s specific conditions. A circuit breaker must never be selected solely based on capacity expressed in BTUs.

Performance, comfort, and considerations with a Hitachi airHome Multi

The Hitachi airHome Multi series uses Inverter technology. The compressor can therefore modulate its output instead of operating only at full capacity or being off. This modulation helps maintain a more stable temperature and reduces short cycling when demand is moderate.

For the two-zone ductless configuration, the manufacturer lists, among other features:

• a rated cooling capacity of 18,000 BTU/h;
• a modulating cooling capacity of 7,000 to 20,500 BTU/h;
• a rated heating capacity of 22,000 BTU/h;
• a modulating heating capacity of 9,000 to 24,000 BTU/h;
• a TRÉS2 of up to 23.0;
• a regional 5 CPSC2 of up to 7.85;
• heating operation down to -20 °C;
• cooling operation from -10 °C to 46 °C.

These figures must always be associated with the exact combination of indoor units. The performance of a multi-zone system varies depending on the selected pairing, the capacity requested simultaneously by each zone, and the outdoor conditions.

Two independent zones, but one shared mode

Each indoor unit can be set to its own setpoint and fan speed. One room can also be turned off while the other continues to operate.

However, there is one important rule for virtually all multi-zone systems: the indoor units share the same primary mode. In summer, they can operate in cooling, dehumidification, or fan mode, depending on the permitted configuration. In winter, they operate in heating or fan mode. Therefore, one unit cannot heat while another is cooling.

This information helps prevent a common operating error. When two remote controls request opposite modes, one of the zones may not respond as expected. We explain this operation to the homeowner during commissioning to prevent unnecessary service calls.

Indoor units suited to different rooms

One of the advantages of the airHome Multi range is the ability to combine several indoor unit formats:

• airHome 400 wall-mounted units;
• airHome 650 wall-mounted units;
• floor consoles;
• mini-cassettes;
• concealed ducted units.

The available indoor capacities generally range from 7,000 to 24,000 BTU/h, depending on the type selected. This flexibility makes it possible, for example, to install a wall-mounted unit in an open-plan area and a more compact unit in a bedroom, or to conceal a ducted unit when the building’s architecture allows it.

Indoor coil filtration and maintenance

Depending on the selected indoor units, the series can include several air treatment and maintenance functions.

The FrostWash technology uses a freeze-and-thaw cycle to help clean the indoor heat exchanger coil and remove certain accumulated contaminants. The Mold Guard function then helps dry the internal components after cooling or dehumidification to limit conditions favorable to odors and mold.

Some units also offer a PM2.5 activated carbon filter or a ViroSense S filter. These features are a useful complement, but they do not replace regular filter maintenance or professional cleaning when significant buildup is present.

R32 refrigerant and leak sensor

The airHome Multi series uses refrigerant R32. Compatible indoor units include a sensor that can trigger an alert if a leak is detected, with a light or audible signal depending on the model and installed accessories.

This feature requires the refrigerant connections to be made precisely and the commissioning to include complete procedures:

1. mechanical verification of the connections;
2. leak test;
3. evacuation;
4. vacuum hold test;
5. opening the valves;
6. heating and cooling test;
7. drainage and control verification.

At AirGreen, we place as much importance on these unseen steps as we do on the exterior finish. A beautiful installation is not enough if evacuation or circuit sealing is neglected.

Mistakes to avoid with a heat pump installed on a balcony

An installation at height or on a balcony involves particular risks. Here are the most common mistakes we aim to eliminate during the planning stage.

Placing furniture in front of the unit

Furniture, storage boxes, and plants must not block air discharge or intake. The owner must maintain the required clearances even after rearranging the balcony.

Allowing leaves to accumulate on the coil

The vegetation visible around this balcony creates a pleasant environment, but it can also produce leaves, seeds, and debris. The outdoor coil should be inspected periodically and cleaned without crushing its fins.

Directing defrost water toward a walkway

In heating mode, a heat pump runs defrost cycles and may discharge water. On a balcony, this water must not be allowed to create an icy patch in a traffic area or flow onto a neighbor’s balcony below.

Obstructing access to the disconnect switch

The electrical enclosure and service panels must remain accessible. A heavy piece of furniture placed directly in front of the unit makes maintenance more difficult and may increase the time required for a service call.

Neglecting the balcony structure

Before installing a unit on a terrace, the surface’s stability must be verified and appropriate support points selected. A heat pump must not rest on deteriorated boards or an unstable support.

Eligibility for rebates: a check to complete before purchase

The manufacturer’s brochure indicates that the airHome Multi range may be eligible for several provincial heat pump incentives. However, this statement does not guarantee that a specific configuration will automatically be accepted.

Eligibility depends in particular on:

• the AHRI number for the complete combination;
• the applicable program criteria;
• low-temperature capacity;
• the type of building;
• the purchase and installation date;
• the documents provided to the homeowner.

Before promising a price, we verify the exact combination of indoor and outdoor units. This process is particularly important for multi-zone systems, since two units from the same series may have different performance ratings and certification numbers.

A result suited to the residential setting of Saint-Lambert

This installation shows that it is possible to integrate a dual-zone heat pump on a balcony without sacrificing the outdoor space. The raised support, grouped lines, and carefully considered equipment placement make it possible to preserve a significant portion of the terrace for occupants.

The context of Saint-Lambert often calls for this type of customized solution. Many properties have narrow balconies, protected facades, shared yards, or closely spaced property lines. A standardized installation is therefore not suitable for every building.

Our work consists of analyzing the entire project: outdoor location, line routing, indoor unit capacities, electrical supply, noise, drainage, and future maintenance. This approach also applies to our installations of multi-zone heat pumps in Montréal, Laval, Longueuil, on the North Shore, and on the South Shore.

An HVAC installation that remains practical after the technicians leave

The quality of an installation can also be assessed several months after the work is completed. The homeowner must be able to clean the balcony, move furniture, access the electrical panel, and have the heat pump serviced without complex disassembly.

In this project, the outdoor unit remains visible and accessible, the lines are grouped together, the support is stable, and the balcony retains its residential function. It is this combination of technical performance and everyday use that characterizes a well-planned HVAC installation.