2-Zone Heat Pump CONFORTO MHMZ | 18,000 BTU - R410A

Two small rooms, two identical heads and a condenser sized to match

Not every home needs a large system. Two bedrooms that overheat in summer, a bedroom and a home office, the two closed rooms of a condo: for these modest needs, the right unit is the one that matches the actual load, not the biggest one. The 2-Zone Heat Pump CONFORTO MHMZ | 18,000 BTU - R410A feeds two wall heads from a single MHMZ218DACFC condenser, compact and sized for two small rooms.

This 1.5-ton condenser serves 2 zones, which is its maximum of 2. The wall head intended for it is the MHWAL09DACFC, installed in each of the two rooms. Its certified ratings are 22.0 SEER2, 12.5 EER2 and 9.8 HSPF2. The system is ENERGY STAR certified with the cold-climate designation under ENERGY STAR ID 4480247, and it qualifies for a $1,800 LogisVert grant.

The right size for two small rooms

A heat pump that is too large for its room heats or cools quickly, stops, then starts again. These short cycles wear out the unit, leave the air humid in summer and create temperature swings. A condenser sized to the rooms instead runs for long periods at low speed, which gives more even comfort and drier air.

This size therefore targets two modest rooms: two bedrooms in a 4 ½ or a 5 ½, a bedroom and an office, a basement bedroom and a workroom. In a well-insulated home, the two heads cover most of the year in these rooms. In an older house, the electric baseboards stay in place for deep cold. The load calculation confirms the choice during the visit.

We are often asked whether a single head, mounted in the hallway between the two rooms, would do the job. With the door open, a little air circulates; with the door closed to sleep or work, almost nothing gets through. One head per room is the only way to guarantee each its own temperature, and that is exactly what a two-zone condenser allows.

Two MHWAL09DACFC heads, two set points

Both rooms get the same head, the MHWAL09DACFC, each with its own remote and set point. You can keep the office comfortable during the day and the bedroom cool at night, or shut off an unoccupied zone entirely without touching the other.

The two heads share the condenser's capacity: when both call at full demand, it is split between them; when only one room is occupied, it benefits from the available capacity. With 2 zones out of a maximum of 2, every connection is used. If a third room needs to be equipped one day, another unit will be required; we tell you before signing, so the choice is made with full knowledge.

Sleep, the first argument

In a bedroom, it is the night that judges a system. The inverter compressor slows down as soon as the set point is reached and holds the temperature without abrupt starts. In summer, extended low-speed operation removes moisture from the air, which lets you sleep cool without setting the set point too low. For cooling, the system is built around a nominal size of 18,000 BTU/h shared between the two rooms.

Compared with a window air conditioner, the difference is clear: the condenser and its compressor are outside, the window stays free and locks, and only a flow of air remains in the room. We mount each head high on the wall so the air sweeps the room without blowing directly on the bed.

In the cold, more capacity than the nominal size

The certificate lists 15,000 BTU/h at -8 °C (17 °F), with a COP of 2.50, and 19,700 BTU/h at -15 °C (5 °F), with a COP of 1.90. It also publishes a maximum capacity of 20,000 BTU/h at -15 °C, with a COP of 1.83. The two points are measured separately; we report each one as published.

The figure at -15 °C exceeds the 18,000 BTU nominal size. This is not an error: in cold weather, the inverter compressor can run faster than its reference speed to offset the home's heat losses. A COP of 1.90 means that at that temperature, each kilowatt-hour consumed returns 1.90 kilowatt-hours of heat, where a baseboard returns one. ENERGY STAR's cold-climate designation confirms that the combination meets the low-temperature performance criteria.

These figures come from certificate AHRI 210605810, published by NEEP.

Backup heat and defrost

The certificate does not publish a point colder than -15 °C. We therefore recommend keeping the existing baseboards, set slightly below the heads' set point: they stay off most of the time and only take over during extreme cold. In cold, humid weather, the condenser also runs defrost cycles of a few minutes. The heads then stop blowing warm air and a cloud of vapour rises from the outdoor unit. This is normal.

Inverter technology and R-410A refrigerant

The condenser meters the R-410A refrigerant sent to each head according to its demand and adjusts the compressor speed accordingly. The two heads always work in the same mode, heating or cooling, as on any multi-zone system of this type. For two neighbouring rooms living through the same season, this rule goes unnoticed.

The 22.0 SEER2, 12.5 EER2 and 9.8 HSPF2 ratings

• SEER2: cooling efficiency over a whole summer.
• EER2: cooling at full load, in hot weather.
• HSPF2: heating efficiency over the whole cold season, the rating that weighs most on the bill in Quebec.
• COP: the ratio between heat delivered and electricity consumed at a specific temperature, here 2.50 at -8 °C and 1.90 at -15 °C.

The $1,800 LogisVert grant

The system is listed in Hydro-Québec's LogisVert program, with $1,800 for the owner of an existing home, according to the list in effect on the installation date. We confirm eligibility before signing and prepare the detailed invoice, model numbers and proof of payment. Our page on the efficient heat pump grant summarizes the program's conditions.

An installation in a condo or a house

Our installation

In a condo, the condenser's location and drilling through exterior walls often fall under the syndicate's authority; check the declaration of co-ownership and obtain approval before the work. The compact condenser is installed on a balcony, on a wall bracket or on a stand, always above the snow line and sheltered from snow sliding off the roof.

Each head gets its own refrigerant line set back to the condenser, protected by a line cover outdoors, and its own sloped condensate drain. The condenser is connected to a dedicated circuit, checked at the panel during the visit. Commissioning includes the vacuum, the leak test, a check of both zones and setup of the remotes with you.

Maintenance

Rinse the filters of both heads every two weeks in season; they come out by hand, without tools. Keep the condenser clear of snow, ice and leaves, without covering it in winter: it heats in January too. One HVAC maintenance visit per year cleans the coils, fans and drains and checks the electrical connections. Our cleaning service takes over when you prefer to hand off the annual visit.

AirGreen, for the life of the installation

A family business active for more than fifteen years in Montreal, Laval, Longueuil, the North Shore and the South Shore, we hold RBQ licences for ventilation, refrigeration and electrical work and carry $5,000,000 in liability insurance. The in-home assessment is free, the quote is in writing, and our financing options let you choose the right unit rather than the cheapest one.

Request your free estimate for the 2-Zone Heat Pump CONFORTO MHMZ | 18,000 BTU - R410A. We assess your two rooms and confirm the right size and your grant eligibility before signing.