A central indoor unit installed in a restricted mechanical space, with full access to its components
This ELIOS electric furnace installation in Venise-en-Québec highlights a part of the central system that homeowners see less often than the outdoor condenser but that plays a decisive role in the comfort of the entire residence: the indoor unit responsible for circulating, heating, cooling, and filtering the air distributed through the ducts.
In the project photo, we see a vertical ELIOS cabinet installed in a narrow mechanical space. The unit occupies nearly the entire width available between the walls, which required precise planning. The unit had to be integrated without compromising access to the service panels, electrical connections, heating elements, condensate drain, or refrigerant connections associated with the system using R454B refrigerant.
The cabinet consists of two main sections. The upper part is the air-handling unit and its technical compartment. The lower section provides access to the connections and components required for central operation. Several safety and technical data labels are visible on the front, including the pictogram associated with an A2L refrigerant.
This installation illustrates an essential HVAC principle: an electric furnace or air handler should not merely fit into the available space. It must be installed so it can be inspected, maintained, and repaired throughout its service life.
An electric furnace integrated with a central heat pump
In this project in Venise-en-Québec, the electric furnace is part of a central ELIOS system designed to operate with an outdoor heat pump. The indoor unit distributes air through the duct network, while the outdoor condenser transfers heat during heating or cooling.
Central-Elios documentation presents a central product line available in several capacities, from 24,000 to 60,000 BTU/h, using R454B refrigerant. The units are designed for cold climates and can be combined with supplemental electric coils ranging from 3 to 25 kW, depending on the equipment capacity, the building’s heating needs, and the electrical configuration.
In everyday language, many homeowners use the expression electric furnace to refer to the entire indoor cabinet. Technically, this cabinet may house several functions:
- the central fan;
- the indoor heat exchanger;
- the detection system associated with R454B;
- the auxiliary electric elements;
- the electronic controls;
- the condensate pan;
- the ductwork connections;
- certain electrical protection devices.
This combination provides heat through the heat pump for most of the season, then adds electric heat when the building’s load exceeds the heat pump’s available capacity or when the system’s programming calls for it.
Why keep auxiliary electric heating?
A central cold-climate heat pump can provide a significant portion of a residence’s heating needs in Venise-en-Québec. However, an electric element remains useful in several situations.
Auxiliary heating can be used to:
- support the heat pump during periods of intense cold;
- heat the house more quickly after a significant thermostat setback;
- provide temporary heating during certain defrost cycles;
- provide backup if the outdoor unit is shut down;
- meet higher-than-expected demand;
- maintain comfort when the building’s heat losses are significant.
The element’s capacity should not be chosen arbitrarily. An undersized element may not meet demand on the coldest days. An oversized element can place an unnecessary load on the electrical panel and lead to higher power demand.
We therefore analyze several factors before determining the appropriate capacity:
- the building’s heat losses;
- the heat pump’s low-temperature capacity;
- the heated area;
- insulation and airtightness;
- the available power at the electrical panel;
- the wire gauge;
- the type of control used;
- the desired operating strategy.
A vertical installation suited to the available space
The unit shown in the photo is installed in a vertical position. This configuration is common when the ductwork is arranged above or below the unit and when the available height allows the components to be stacked.
However, the mechanical space in this residence presented several constraints:
- limited width around the cabinet;
- nearby walls;
- limited clearance in front of the unit;
- connections that must remain accessible;
- need to remove the panels without moving the unit;
- existing floor to be protected;
- a duct network that must be precisely aligned.
In such a tight space, a few centimeters can make the difference between a functional installation and a unit that is nearly impossible to service.
In particular, we must allow sufficient clearance to:
- remove the fan panel;
- access the electrical compartment;
- check the heating elements;
- measure voltage and current;
- inspect the indoor heat exchanger;
- Clean the condensate pan;
- access the safety sensor;
- replace certain parts without removing the entire cabinet.
A common mistake is to choose the unit based solely on its capacity, without checking its physical dimensions. The Central-Elios range includes several cabinet sizes. Depending on capacity, the indoor units measure approximately 17.52 to 24.49 in. wide, 21.02 in. deep, and 45 to 52.99 in. high. Their net weight varies approximately from 105.6 to 162.9 lb.
These differences in dimensions can be highly significant in a basement, mechanical closet, or narrow equipment room.
R454B refrigerant and integrated safety features
The installed system uses R454B, a new-generation refrigerant classified as A2L. This classification means that it has low flammability and must be handled with suitable tools, procedures, and safety measures.
On the front of the unit, the safety pictogram clearly indicates the presence of a refrigerant requiring special precautions. This identification is important for technicians who will subsequently work on the system.
The Central-Elios range includes a leak detection device. According to the manufacturer, the sensor monitors for the possible presence of refrigerant. If detected, the system can stop the compressor, maintain airflow, and generate a service alert.
This controlled airflow helps disperse any potential concentration of refrigerant in the cabinet and ducts. For this device to operate as intended, several conditions must be met:
- the sensor must be properly installed and connected;
- the wiring must comply with the manufacturer's diagram;
- the cabinet openings must not be modified arbitrarily;
- the panels must remain properly closed;
- the airflow must comply with the required parameters;
- compatible components must be used together.
We also avoid improvised substitutions. An R454B system must be installed according to the instructions specific to the selected indoor and outdoor combination, rather than according to practices associated with an older R410A unit.
Visible connections in the lower section
The lower part of the photographed unit has several connection points. Plugs, service openings, and components associated with the drainage or indoor circuit can be seen.
These connections must be positioned to allow servicing without having to remove the entire furnace. We pay particular attention to their orientation, because a connection placed too close to a wall becomes difficult to tighten, test, or replace.
Condensate drainage
In cooling mode, the indoor heat exchanger removes moisture from the air. This water must be collected and discharged through a properly installed drain.
Poor drainage can cause:
- water leaks;
- cabinet corrosion;
- floor damage;
- moisture accumulation;
- mold growth;
- a shutdown triggered by a safety switch;
- a decrease in dehumidification capacity.
The technical documentation indicates a moisture-removal capacity that varies by model, ranging from approximately 2.05 to 5.87 liters per hour under the specified test conditions. This shows that a central system can produce a significant amount of water during hot, humid days.
The drain must therefore have an adequate slope and remain accessible for cleaning. Depending on the configuration, a trap, vent, or condensate pump may be necessary.
Refrigerant connections
The refrigerant lines connect the indoor heat exchanger to the outdoor condenser. For the Central-Elios range, the documentation generally specifies 3/8-inch liquid-side lines and 3/4-inch gas-side lines.
These dimensions must be validated according to the exact model. We also verify:
- the total line length;
- the height difference;
- the condition of the insulation;
- the quality of the brazed joints;
- the tightness of the circuit;
- the required refrigerant charge;
- protecting the lines from rubbing.
For a new R454B installation, the leak test and evacuation must be performed with great care. A small leak can reduce performance, trigger the safety system, and compromise the compressor’s service life.
Air distribution, an element as important as the equipment
An ELIOS electric furnace cannot provide uniform comfort if the duct network is too restrictive or poorly balanced.
The fan must move enough air through the heat exchanger and ducts. Insufficient airflow can lead to:
- excessive temperature around the electrical elements;
- poor distribution between rooms;
- ice formation in cooling mode;
- significant air noise;
- short cycles;
- reduced efficiency;
- premature motor wear.
Conversely, excessive airflow can create drafts and unpleasant noise at the grilles.
When starting the system, we check, among other things:
- system static pressure;
- fan speed;
- return air temperature;
- supply air temperature;
- operation of the electrical elements;
- thermostat response;
- filtration quality;
- the absence of abnormal vibrations.
The outdoor system’s Inverter technology modulates output. This modulation must be accompanied by suitable airflow so that the home can truly benefit from more stable operation.
The power supply for a central furnace
The indoor unit and heating elements can represent a significant electrical load. The circuit must therefore be sized according to the model specifications and the capacity of the installed auxiliary heating.
A proper inspection includes, in particular:
- available voltage;
- conductor gauge;
- panel capacity;
- the type of circuit breaker;
- the presence of a ground connection;
- terminal tightening;
- cable protection;
- compliance of the electrical entries in the cabinet.
The heating element’s electrical power is expressed in kilowatts. As a guideline, a 10 kW element requires much more current than a 5 kW element. The selection therefore directly affects the wiring, circuit breaker, and required electrical capacity.
It is important not to assume that an old circuit is automatically suitable for the new furnace. Even when the unit is installed in the same location, the requirements may differ.
Errors to avoid in a restricted mechanical room
This installation in Venise-en-Québec highlights several common errors.
Block the service panels
A shelf, a water heater, or a wall added too close to the unit can prevent access to the components.
Neglecting filtration
A filter that is too restrictive or completely clogged reduces airflow. The filter must be the correct size and replaced according to the home’s actual usage.
Installing an electric element without checking the electrical panel
The auxiliary heating capacity must be compatible with the home’s electrical service.
Completely enclosing the cabinet in an improvised space
The unit must maintain the clearances required for maintenance and safe operation.
Forgetting the condensate drain
The drain must be tested in cooling mode, not merely observed visually.
Reusing incompatible control wiring
An inverter heat pump and an R454B system may require specific controls. The connections must follow the manufacturer’s diagram.
Choosing capacity based solely on floor area
Sizing must account for heat loss and the ductwork system, not just the number of square feet.
An indoor installation designed to facilitate maintenance and extend the system’s lifespan
Front access as a priority
The photo shows that the main panels face the work area. This arrangement is important because most service work is performed from the front.
During HVAC maintenance, the technician may need to:
- Open the electrical compartment;
- Inspect the motor;
- Test the heating elements;
- Clean the condensate pan;
- Check the R454B sensor;
- Measure the airflow;
- Check the connections;
- Examine the indoor heat exchanger.
Even if space is limited on the sides, adequate front access allows essential operations to be performed without moving the unit.
Recommended checks for the homeowner
To maintain the proper operation of the electric furnace and central heat pump, we recommend that the homeowner:
- Check the filter regularly;
- Do not store anything directly in front of the panels;
- Watch for traces of water near the cabinet;
- Avoid changing the technical settings;
- Keep the return-air grilles unobstructed;
- Report any thermostat alert promptly;
- Have the system checked in the event of unusual noise;
- Schedule periodic professional maintenance.
The filter deserves special attention. In an occupied home, its lifespan depends on the presence of pets, renovation work, dust, and the number of operating hours. A filter should not be replaced solely according to a fixed date without checking its condition.
Energy efficiency and eligibility for financial incentives
The Central-Elios range offers efficiencies of up to 18.3 SEER2 in cooling and up to 8.6 HSPF2 in Region V in heating, depending on capacity. The combinations listed in the brochure are recognized as ENERGY STAR 6.1 and ENERGY STAR Cold Climate.
These characteristics may make certain combinations eligible for financial assistance programs. However, eligibility must never be presumed solely from the ELIOS name or the R454B refrigerant.
The following must be confirmed:
- the exact indoor model number;
- the exact outdoor model number;
- the certified combination;
- the applicable energy reference number;
- the purchase and installation date;
- the type of residence;
- the criteria of the program in effect.
The labels are visible in the photo, but their detailed content is not clear enough to confirm the exact capacity or model number. It would therefore be inappropriate to assign a BTU rating or subsidy amount without consulting the project documents.
The final result in Venise-en-Québec
This ELIOS Central-Elios R454B electric furnace installation in Venise-en-Québec addressed a clear challenge: integrating a new central unit into a very restricted indoor space while maintaining functional access to all important components.
The unit was installed vertically, with the service panels facing forward. The cabinet sections are properly aligned, and the lower connections remain accessible. The presence of safety labels related to R454B also highlights that newer generations of central systems require appropriate training and methods.
At AirGreen, we place as much importance on the indoor unit as on the outdoor condenser. A central heat pump may have excellent specifications, but its actual performance depends on airflow, auxiliary heating, drainage, electrical connections, and mechanical accessibility.
We apply this same rigor to our electric furnace and central heat pump projects in Montreal, Laval, Longueuil, the North Shore, and the South Shore. Each building presents its own constraints, whether it involves a small mechanical room, a finished basement, or a replacement within an existing duct network.
A well-planned installation makes maintenance easier, protects the components, and allows the ELIOS system to deliver consistent comfort throughout the home, summer and winter.