Central Heat Pump ADD-ON ARCOAIRE H4H5S ION | 1.5 Tons - 18,000 BTU (Coil EVD4X 14.5 in.) - R410A

A 14.5 in. coil that fits the electric furnace you already have

The ADD-ON system adds a heat pump to an existing electric furnace: a coil is installed on the furnace and the outdoor unit heats and cools through the same ducts. The furnace's elements are only used as backup. The Central Heat Pump ADD-ON ARCOAIRE H4H5S ION | 1.5 Tons - 18,000 BTU (Coil EVD4X 14.5 in.) - R410A pairs the H4H5S18AKAAA outdoor unit, from the ION series, with the EVD4X18M14A coil.

The whole project rests on one point: the electric furnace in place becomes the base of the new system. Its blower will move the heat pump's air, its air outlet will receive the coil and its duct network will distribute warmth as well as cool air. Before talking about the outdoor unit, we therefore look at the furnace.

What your furnace needs to offer

An electric furnace can accept a heat pump coil, on a few conditions. It must be in good condition and still have several years of service ahead of it, and its heating elements must be reliable, since they will serve as backup: grafting a new system onto a furnace at the end of its life means reopening the job a few winters later. Its blower must be able to move the airflow the coil requires. And there must be room above the air outlet to set the coil and rebuild the plenum.

We check the condition of the electric furnace and its elements, the airflow of its blower and the duct sizes before the quote. If the furnace shows signs of advanced wear, we tell you frankly, and we present the option of a complete central system alongside.

The 14.5 in. EVD4X coil

The EVD4X18M14A coil sits on the furnace's air outlet, in the supply plenum, after the heating section. Its 14.5 in. dimension must match the furnace: when the two line up, the connection is direct; when they differ, we fabricate a sealed transition so that all the air passes through the coil with no leakage around it.

Height matters as much as width. In a basement with a low ceiling or a mechanical closet, the space between the top of the furnace and the joists can be tight; we measure it during the visit to plan how the plenum and duct take-offs are rebuilt. The coil also has its own pan and condensate drain, which we route to a floor drain or a pump with a steady slope.

The furnace blower works for two

In an ADD-ON system, the heat pump has no indoor blower of its own: the furnace blower pushes the air through the coil. Its settings must therefore suit a 1.5-ton coil, in cooling as in heating. Airflow that is too low makes the coil freeze in summer and reduces efficiency in winter; airflow that is too high makes the grilles whistle and removes less humidity. We adjust the blower speeds at commissioning and check the result at the grilles.

Which homes this size suits

The 1.5-ton size is meant for compact homes already equipped with a forced-air electric furnace: a small, well-insulated bungalow, a townhouse, a semi-detached house, or a duplex unit with its own furnace and its own ducts. With an ADD-ON system, the heat pump is chosen first according to cooling needs, since the furnace's elements cover the deep cold; a unit larger than necessary would cool in fits and starts.

Insulation, windows, orientation and airtightness count as much as the size of the house. The room-by-room load calculation confirms the size before the quote.

Sharing the seasons

A heat pump moves heat instead of producing 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. In fall, in spring and through a good part of winter, the heat pump heats alone. When the cold becomes too sharp for it, the thermostat brings in the furnace's electric elements as backup. This pairing does not carry the cold-climate designation: the furnace's electric backup remains there for the coldest nights.

The elements come in when the heat pump can no longer hold the set point, and the thermostat takes them out as soon as it is enough again. During defrost, the elements can also heat for a few minutes so that the air from the grilles stays warm.

Drier air in summer

In cooling mode, the air passes through the cold coil, which removes heat and humidity at the same time. A properly sized unit runs long enough on each cycle to dry the air well. You notice it in the bedrooms, where sleep is more comfortable, and in the basement, where the damp smell recedes when the ducts serve it.

System ratings

The pairing of the H4H5S18AKAAA outdoor unit and the EVD4X18M14A 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. For this reason, this page 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. The program's general conditions are on our page on the grant for efficient heat pumps.

Installation by AirGreen

Outdoor unit and refrigerant line

The outdoor unit goes on a wall bracket or a pad, above the snow line, away from roof drips, dryer vents and bedroom windows. We choose a spot where defrost water drains without freezing on a walkway and where the unit stays accessible for maintenance. The insulated copper line follows the shortest possible route to the coil; it is brazed, pressure tested and put under vacuum before the valves are opened.

In a townhouse or a semi-detached house, the side yard is often narrow and the neighbour's window is never far. Some municipalities also regulate where outdoor equipment may go. We take these constraints into account when choosing the location and present it to you before the work, so that the unit ends up neither under a gutter nor in front of a bedroom window.

Electrical, thermostat and commissioning

The outdoor unit requires a dedicated circuit and a nearby disconnect; in a house heated by an electric furnace, where the panel is often already heavily loaded, we check during the visit that it has the space needed. A compatible thermostat decides when the heat pump heats alone and when the furnace's elements add backup heat; a furnace-only thermostat cannot do this, and we replace it.

At commissioning, we check the refrigerant charge, the airflow, defrost and how the electric backup comes in, then we set with you the moment the furnace's elements step in.

Maintenance and warranty

The furnace filter now serves both appliances, summer and winter: check it every month and replace it according to its format. Keep the outdoor unit clear of snow and leaves, and 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 H4H5S ION | 1.5 Tons - 18,000 BTU (Coil EVD4X 14.5 in.) - R410A. We examine your furnace, measure the space for the coil and confirm the right size and your grant eligibility before signing.

Available while supplies last.