Central Heat Pump ADD-ON ARCOAIRE HSH6 Premium | 2 Tons - 24,000 BTU (Coil EVD4X 14.5 in.) - R410A

A two-level cottage, ducts already in place and a more even temperature from one level to the next

In a cottage heated by a forced-air electric furnace, the temperature gap between the main floor and the upper floor returns every summer: the upstairs bedrooms hold the day's heat while the basement stays cool. The ADD-ON system brings air conditioning through the existing ducts and hands most of the year's heating to the heat pump rather than the elements, without removing the furnace.

The Central Heat Pump ADD-ON ARCOAIRE HSH6 Premium | 2 Tons - 24,000 BTU (Coil EVD4X 14.5 in.) - R410A pairs the HSH624GKA outdoor unit with the coil EVD4X24M14A. The HSH6 series is presented as the premium tier of this Arcoaire family. In a cottage, the choice of equipment matters, but the way the air reaches the upper floor matters just as much.

What the ADD-ON system does

The coil is installed on the furnace's air outlet, and an outdoor unit is connected to it by a copper line. In summer, the R-410A refrigeration circuit removes heat and humidity from the air passing through the coil. In winter, a reversing valve flips the cycle: the heat pump captures heat from the outdoor air and delivers it to the coil. In both cases, the furnace blower pushes the air into the ducts. The furnace's electric elements are only used as backup, for the deep cold.

Which cottages the 2-ton size suits

The 2-ton size is aimed at a modest cottage, a two-level townhouse with a basement or a semi-detached house, provided the envelope is reasonably insulated. With an ADD-ON system, the heat pump is sized first on cooling, since the furnace's elements cover the coldest nights. A larger cottage, or one whose upper floor sits under a poorly insulated roof, may call for the next size up.

The room-by-room load calculation takes into account what weighs most in a cottage: the attic above the bedrooms, windows exposed to the afternoon sun and air leaks around the upstairs windows. It is what confirms the size before the quote.

Why the upper floor stays warmer in summer

A cottage's upper floor receives heat from the roof, and the warm air of the house accumulates there. The original ducts were designed for the furnace: they send warm air to grilles often located low on the walls, and that air naturally ends up rising to the upper floor. In cooling, the logic reverses. Cool air, being heavier, tends to stay down, and the upper floor only gets its share if the ducts going up are large enough and if the air can return to the furnace.

During the visit, we therefore check the number and size of the supplies serving the upper floor, whether there are return air openings upstairs, and the condition of ducts running through walls or the attic.

Return air upstairs

A cottage built for an electric furnace alone sometimes has a single return, on the main floor or in the basement. In heating, that works; in cooling, the warm air built up upstairs has no path back to the coil. A closed bedroom without a return becomes the warmest room in the house. Depending on the layout, an additional return upstairs, a transfer grille or a clearance under the doors improves things noticeably; we state in the quote what your house requires.

Balancing airflow by season

The dampers on the grilles and main ducts let you split the air between levels. In summer, more is sent upstairs and less to the basement; in winter, you can return to a more even setting. We do an initial balancing at commissioning and show you where the dampers are. The fan circulation mode offered by most thermostats can also help narrow the gap between levels during hot spells.

One precaution: avoid fully closing a large number of grilles in the basement. The coil needs enough airflow to work properly; too many closed grilles starve it of that air, make the remaining ones whistle and can cause the coil to freeze in cooling mode. Better to reduce than to close.

Heating with the heat pump, then with the electric backup

In fall, in spring and through a good part of winter, the heat pump heats alone. When the cold becomes too sharp for it, a compatible thermostat brings in the furnace's electric elements as backup, then takes them out as soon as the heat pump is enough again. This pairing does not carry the cold-climate designation; in an ADD-ON system, the furnace's electric backup is precisely what covers the coldest nights.

The air the heat pump delivers is milder than the air from the furnace's elements, and the cycles are longer. In a cottage, this gentler operation mixes the air between levels for longer. During defrost, the furnace's elements may heat for a few minutes so that the air from the grilles stays warm.

Dehumidification in summer

The cold coil removes humidity from the air, and the condensed water flows through a drain to a floor drain or a pump. A right-sized unit runs long enough on each cycle to dry the air well; upstairs, under a roof warmed by the sun, that difference is felt from the first hot night.

System ratings

The pairing of the HSH624GKA outdoor unit and the EVD4X24M14A coil is not listed with SEER2 ratings in the AHRI certification directory. We confirm the ratings of the complete system before the quote; they also determine grant eligibility. That is why no rating figure appears on this page.

LogisVert

This pairing does not carry an amount on Hydro-Québec's LogisVert list of October 19, 2026. If the grant matters for your project, we will point you to an eligible pairing of comparable size. Our page on the grant for efficient heat pumps summarizes the program's conditions.

Installation in a cottage

From the visit to commissioning

We check the condition of the electric furnace and its elements, the airflow of its blower and the duct sizes before the quote. The blower must be able to push air all the way to the upstairs bedrooms through a 2-ton coil. The 14.5 in. coil is set on the furnace's air outlet; if it does not line up, we fabricate a sealed transition. Its condensate drain goes to a floor drain or a pump.

The outdoor unit goes on a bracket or a pad, above the snow line, away from roof drips and bedroom windows, and it gets a dedicated circuit with a disconnect. The insulated copper line is brazed, pressure tested and put under vacuum. The thermostat goes in a central room on the main floor, out of direct sun and drafts. Commissioning includes the refrigerant charge, airflow, defrost, the setting of the electric backup and balancing of the dampers.

Maintenance and warranty

The furnace filter now works all year: check it every month and replace it according to its format. Keep the outdoor unit clear of snow and leaves. Plan annual HVAC maintenance of the coil, the condensate drain and the electrical connections, in addition to a check of the electric furnace and its elements. In winter, white vapour during defrost is normal.

Warranty: 10 years on the compressor, 10 years on parts and 6 years on labor.

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 Central Heat Pump ADD-ON ARCOAIRE HSH6 Premium | 2 Tons - 24,000 BTU (Coil EVD4X 14.5 in.) - R410A. We assess the cottage room by room, from the upper floor to the basement, and confirm the right size and your grant eligibility before signing.

Available while supplies last.