Central Heat Pump ADD-ON ARCOAIRE H4H5S ION | 2 Tons - 24,000 BTU (Coil EVD4X 14.5 in.) - R410A
Keep an electric furnace in good condition and leave its elements only the deep cold
A well-maintained electric furnace often still has good years ahead of it. The ADD-ON system makes use of that: instead of replacing it, a coil and an outdoor unit are added that heat and cool through the same ducts. Its elements are only used as backup, during the cold the heat pump does not cover alone, and they run far fewer hours per year.
The Central Heat Pump ADD-ON ARCOAIRE H4H5S ION | 2 Tons - 24,000 BTU (Coil EVD4X 14.5 in.) - R410A pairs the H4H5S24AKAAA outdoor unit, from the ION series, with the EVD4X24M14A coil. Before proposing it, we first check one thing: that your electric furnace deserves to stay in place for the years ahead. That finding guides the whole project.
ADD-ON or complete system: the starting point
The ADD-ON system makes sense when the furnace is in good condition, its blower can move the airflow of a 2-ton coil and the ducts are adequate. You then keep an appliance that works, add air conditioning, and the heat pump takes over most of the heating.
If the furnace is nearing the end of its life, the logic changes. Grafting a new coil onto an appliance that will need replacing in a few winters means redoing part of the work at that point. In that case, we also present the option of a complete central system, and you choose knowing both.
Signs of a furnace that can stay
A few clues help judge. A furnace serviced every year, without repeated breakdowns, whose blower starts and runs without unusual noise, is generally a good candidate. A previous maintenance report, if you have one, is valuable: it describes the condition of the blower, the heating elements and their connections. Those elements matter most of all, since they become the heat pump's backup.
On our side, we check the condition of the electric furnace and its elements, the airflow of its blower and the duct sizes before the quote. If we see signs of advanced wear, we tell you before you sign.
What the ADD-ON system adds
The coil sits on the furnace's air outlet, and the outdoor unit is connected to it by a copper line. A heat pump does not produce its heat, it moves it: in winter, its refrigerant, R-410A, captures heat from the outdoor air and delivers it to the coil; in summer, a reversing valve flips the cycle and rejects the heat of the house outdoors. The furnace blower pushes the air through the coil and into the ducts, whatever the season.
Inside the house, little changes: the grilles, the ducts and the location of the filter stay the same. What changes is the thermostat, which now controls the heat pump and the electric backup, and the outdoor unit, which also runs in winter. The air coming out of the grilles when the heat pump is heating is milder than the air from the furnace's elements, and the cycles are longer: that is normal heat pump operation.
Which homes this size suits
The 2-ton size is aimed at mid-sized homes equipped with a forced-air electric furnace: a bungalow with a basement, a semi-detached house, a roomy townhouse or a modest cottage. With an ADD-ON system, the heat pump is sized first on cooling, since the furnace's elements cover the deep cold; an oversized unit would cool in fits and starts and leave humidity in the air. Insulation, windows, orientation and the airtightness of the house count as much as its size, and the room-by-room load calculation confirms the size.
Each appliance's role through the year
In fall, the heat pump takes over heating from the first cool evenings. Through a good part of winter, it keeps heating alone. When the cold becomes too sharp for it, the furnace's elements join in as backup and cover the coldest nights; this pairing does not carry the cold-climate designation, and that is precisely the role of the electric backup in an ADD-ON system. In spring, the heat pump takes back control. In summer, it cools and dehumidifies the whole house.
The result: the furnace's elements, which used to heat from October to May, now serve only during the coldest periods. They wear more slowly, and the heat pump covers most of the year.
The thermostat that coordinates the two
A compatible thermostat decides when the heat pump heats alone and when the furnace's elements join in as backup. As long as the heat pump holds the set point, the elements stay off; when it is no longer enough, the thermostat brings them in, then takes them out as soon as it is enough again. During defrost, the elements can heat for a few minutes so that the air from the grilles stays warm.
The moment the backup comes in is set according to your house and your comfort preferences. We set it with you at commissioning and show you how to change it.
Cooling and humidity
In cooling mode, the cold coil removes heat and humidity from the air; the 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, which makes the house more comfortable at the same temperature. We also check the return air: a closed bedroom without a return stays warmer than the rest of the house.
System ratings
The pairing of the H4H5S24AKAAA 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. This page therefore shows no rating figure.
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 and follow-up
The installation
The 14.5 in. coil is set on the furnace's air outlet; if it does not line up with it, we fabricate a sealed transition. Its condensate drain goes to a floor drain or a pump. The outdoor unit is installed on a bracket or a pad, above the snow line, away from roof drips and dryer vents. The insulated copper line is brazed, pressure tested and put under vacuum before the valves are opened.
The outdoor unit gets a dedicated circuit and a disconnect, and the new thermostat is wired to the furnace and the outdoor unit. At commissioning, we check the refrigerant charge, airflow, defrost and how the electric backup comes in.
Maintaining both appliances
An ADD-ON system has two appliances, and each deserves its maintenance. The electric furnace needs a check of its blower, its elements and their connections. The heat pump requires annual HVAC maintenance of the coil, the condensate drain and the electrical connections. Between visits, check the filter every month, since it now works all year, and keep the outdoor unit clear of snow and leaves. 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 H4H5S ION | 2 Tons - 24,000 BTU (Coil EVD4X 14.5 in.) - R410A. We examine your furnace with you and confirm whether the ADD-ON system is the right choice, the right size and your grant eligibility before signing.
Available while supplies last.