A custom integration in a mechanical room where the duct network dictated every decision
In Verchères, on Montreal’s South Shore, our AirGreen team installed an ELIOS Central-Elios electric furnace compatible with a central heat pump using R454B refrigerant in a mechanical room already structured around an extensive network of metal ducts.
The photograph was taken during an intermediate stage of the work. It shows the new ELIOS indoor unit positioned to the left of a large return-air cabinet, with the refrigerant lines, PVC drain, control cables, and sheet-metal sections still accessible before final enclosure and commissioning.
This configuration illustrates a common reality when replacing a central system: the new furnace cannot be installed without considering what is already there. It must integrate with the building’s mechanical infrastructure, distribution network, electrical capacity, and access constraints.
In this project, the main challenge was not simply placing the unit in the room. We had to coordinate the new ELIOS electric furnace, the large adjacent vertical duct, the upper plenum, the air return, the condensate drain, and the connections to the outdoor system, while preserving enough space for future HVAC maintenance.
An installation where custom sheet metal plays a central role
To the right of the ELIOS unit, a substantial section of galvanized sheet metal forming the central system is visible. The lower section serves as a large cabinet, while the upper section transitions to connect with the building’s ducts.
This type of system is not merely a cover. It controls how air returns to the furnace, passes through the filter and coil, and then moves on to the various rooms.
When replacing a central unit, the dimensions of the new cabinet rarely match those of the old furnace exactly. We therefore need to fabricate or modify sheet-metal transitions to achieve a stable, airtight connection.
A quality adaptation must:
- maintain sufficient clearance;
- limit abrupt changes in direction;
- reduce turbulence;
- prevent leaks around the joints;
- withstand normal vibrations;
- preserve access to the service panels;
- allow the filter to be replaced easily.
In the photo, the proximity between the furnace and the large cabinet demonstrates why measurements taken before ordering are essential. A few inches of error could have complicated the connection, blocked a service door, or required a much more restrictive transition.
An electric furnace paired with a central heat pump
The indoor unit installed in Verchères is part of a central heat pump system. It does much more than provide supplemental electric heat.
In a Central-Elios configuration, the indoor unit serves several functions:
- circulate air through the ductwork;
- receive the refrigerant coil;
- distribute the heat produced by the heat pump;
- distribute cooled air during the summer;
- activate the electric elements when supplemental heat is required;
- handle thermostat demands;
- coordinate the sequences with the outdoor unit.
The term “electric furnace” remains common and understandable to homeowners, but technically, this unit also functions as a central fan coil and as the indoor component of the heat pump.
The Central-Elios product line is available in nominal capacities of 24,000, 30,000, 36,000, 48,000 and 60,000 BTU, with a dedicated indoor and outdoor model for each combination. The documentation also indicates efficiencies of up to 18.3 TRÉS2 and 8.6 CPSC2, depending on the selected capacity.
Why We Do Not Infer Capacity from the Photo
The cabinet visible in Verchères resembles the various units in the product line, but the model label is not clear enough to confirm the capacity precisely.
We therefore avoid claiming that it is a 24,000, 30,000, or 36,000 BTU unit based solely on its apparent size.
This caution is important because the dimensions are similar for some capacities. The 30,000 and 36,000 BTU models, for example, both use an indoor cabinet approximately 21.02 in. wide, 21.02 in. deep, and 49.02 in. high. The 48,000 and 60,000 BTU models also share larger dimensions.
The exact capacity must always be confirmed using:
- the indoor model number;
- the outdoor model number;
- the nameplate;
- the certified combination;
- the building load calculation.
Sizing based on actual heat loss
In Verchères, as throughout the South Shore, the capacity selection must take winter temperatures and the building's characteristics into account.
We analyze, among other things:
- living area;
- insulation quality;
- airtightness;
- window area;
- wind exposure;
- ceiling height;
- the number of floors;
- the condition of the ductwork;
- the needs of remote rooms;
- the capacity of the electrical panel.
A furnace that is too small may lack sufficient airflow or rely excessively on electric heating. A furnace that is too large may cause short cycling, noise, and less uniform distribution.
The right approach is to coordinate the heat pump, fan, coil, ductwork, and auxiliary heating rather than selecting the largest available capacity.
R454B and A2L safety
The mention R454B refers to the refrigerant used in the refrigeration circuit between the indoor and outdoor units. This refrigerant belongs to the A2L category, meaning slightly flammable refrigerants.
This classification does not change the owner's day-to-day use, but it imposes specific requirements on the installer.
In a Central-Elios system, the documentation mentions integrated leak detection. If an anomaly is detected, the system is designed to stop the compressor, maintain airflow, and send a service alert.
During our HVAC installation, we must, among other things:
- use instruments compatible with R454B;
- check the integrity of the piping;
- perform a leak test;
- perform a thorough vacuum evacuation;
- comply with the charge requirements;
- confirm the safety devices;
- avoid any improvisation in the connections.
The refrigerant lines visible above the furnace
The photograph shows two refrigerant lines entering the upper section of the unit. The larger one is insulated, while the smaller one carries liquid refrigerant.
For the Central-Elios range, the documentation generally specifies a liquid line of 3/8 po and a gas line of 3/4 po for the five capacities. The maximum permitted lengths vary by model, reaching up to 164 feet for some capacities and up to 246 feet for higher-capacity models.
However, these values must be verified for the exact combination before installation.
We always check:
- pipe diameter;
- total length;
- height difference;
- insulation quality;
- bends and changes in direction;
- protection against sharp metal edges;
- the amount of refrigerant to add, if necessary.
An improperly sized line can reduce efficiency, affect oil return, and harm the compressor.
The white PVC condensate drain
To the left of the furnace, a white PVC pipe rises vertically before connecting to the unit.
This drain is used to discharge the water generated when the system operates in cooling mode. Moisture in the air condenses on the cold coil and must be directed to a suitable drain point.
A drain installation must meet several conditions:
- sufficient slope;
- watertight connections;
- access for cleaning;
- adequate support;
- protection against backflow;
- absence of a reverse slope;
- compatibility with the coil configuration.
An improperly installed condensate line can cause water on the floor, damage to materials, odors, or a safety shutdown.
In this mechanical room in Verchères, the vertical routing keeps the drain grouped along the structure without unnecessarily crossing the service area in front of the furnace.
The visible wires indicate a stage of the work, not the final condition
Several cables and conductors still appear to be loose in the photograph. It is important to clarify that the image shows an installation in progress, before final closure, complete connection, and testing.
This step enables the technicians to:
- identify the old conductors;
- confirm the control functions;
- check thermostat compatibility;
- connect the heating stages;
- connect the indoor unit to the outdoor unit;
- test the existing accessories;
- remove wires that are no longer needed.
During a replacement, wire colors are not always enough to identify their function. A previous installer may have used a conductor for a different function than the one normally associated with its color. We therefore confirm the circuits using the wiring diagram and measurements rather than relying on a visual match.
The manual control visible on the plenum
In the upper section of the large metal cabinet, a small device with a rotary knob can be seen. It may be a control associated with a network accessory, such as a damper, humidifier, or existing ventilation function.
The photo does not make it possible to confirm its exact purpose. During a replacement, we identify these accessories before reconnecting them.
We specifically check:
- their power supply;
- their condition;
- their compatibility with the new furnace;
- their impact on airflow;
- their operating sequence;
- their actual usefulness to the owner.
Automatically keeping every old accessory is not always advisable. Some may be obsolete, defective, or poorly suited to the new system.
An installation approach focused on airflow, accessibility, and commissioning
The existing duct network must accommodate the airflow of the new unit
One of the main risks when replacing a furnace is installing a high-performance unit on an overly restrictive duct network.
The large cabinet visible to the right of the unit suggests a significant return or distribution volume, but a complete assessment requires measurements.
We specifically check:
- static pressure;
- the size of the main ducts;
- the number of return ducts;
- filter restrictions;
- closed dampers;
- overly tight elbows;
- undersized transitions;
- noise at the grilles.
Insufficient airflow can reduce coil performance and cause uneven distribution. Excessive airflow can increase noise and limit dehumidification in summer.
Inverter technology and comfort at low temperatures
The Central-Elios range uses an inverter compressor capable of modulating its speed according to demand.
The documentation indicates that the system can provide up to 100% of its rated capacity at -20 °C and continue operating in heating mode down to -30 °C. At -30 °C, the available capacity represents approximately 69% to 76% of the rated capacity, depending on the model.
For a Verchères homeowner, this modulation offers several concrete advantages:
- more stable indoor temperature;
- longer, less abrupt cycles;
- reduced cycling;
- fewer variations between rooms;
- more gradual use of the backup heating;
- better comfort during very cold periods.
The auxiliary electric heating must be coordinated with the heat pump
Central-Elios documentation mentions electric backup coils available from 3 to 25 kW.
The choice of this capacity depends on the load calculation, the electrical panel, and the heating strategy.
An oversized kit can:
- require additional electrical work;
- increase peak demand;
- operate unnecessarily if the thermostat is improperly adjusted;
- reduce the savings achieved by the heat pump.
We therefore aim to have the heat pump operate as the primary source and activate the electric backup only when necessary.
An installation that is accessible for future maintenance
The furnace was positioned with its front facing the service area. This arrangement facilitates opening the panels.
Access must remain sufficient to:
- inspect the electronic control board;
- check the heating elements;
- access the fan;
- clean the coil;
- measure the electrical values;
- check the R454B sensor;
- work on the drain;
- perform a diagnostic.
An installation that is too cramped can turn a simple repair into a lengthy service call. We therefore plan for maintenance from the initial positioning stage.
Final commissioning
Once the connections are complete and the panels have been put back in place, we perform full commissioning.
This check generally includes:
- supply voltage;
- connection tightness;
- electrical protections;
- communication between the units;
- fan speeds;
- heat-pump heating;
- electrical stages;
- air conditioning;
- drainage;
- supply and return temperatures;
- static pressure;
- safety devices.
We also check for noise, vibration, and air leaks around the new sheet-metal sections.
Energy performance and certifications
Depending on capacity, the Central-Elios range has a SEER2 from 16 to 18.3 and a regional HSPF2 from 8 to 8.6. The configurations presented in the documentation are certified ENERGY STAR V6.1 and ENERGY STAR Cold Climate.
These performance figures vary by combination. The maximum rating of 18.3, for example, applies to the 24,000 BTU system, while the 36,000 BTU model has a SEER2 of 17.3.
Therefore, always compare the values for the system actually being proposed rather than relying on a single promotional value representing the entire range.
Sound level and compact outdoor unit
The documentation indicates an outdoor sound level ranging from 60 to 65 dB(A), depending on capacity. The horizontal-discharge outdoor unit is presented as being up to 40% more compact than some traditional vertical models.
This design can make installation easier in a side yard or limited space, a relevant advantage in Verchères as well as in denser areas of Longueuil, Montréal or Laval.
Mistakes to avoid during a similar replacement
Overlooking the large return-air cabinet
The return air must be evaluated as carefully as the furnace. A significant restriction can reduce the performance of the new equipment.
Reusing refrigerant lines without verification
The diameter, cleanliness, insulation, and compatibility must be confirmed for R454B.
Choosing the maximum electrical capacity by default
The auxiliary heating capacity must meet the building’s actual needs, not an oversizing strategy.
Blocking service access with a sheet-metal transition
The front and side panels must remain accessible after the ductwork is closed.
Confusing the model with the refrigerant
R454B is the refrigerant type. The actual model must be identified using the complete reference numbers for the indoor and outdoor units.
Omitting the airflow adjustment
The fan must be configured according to the tonnage, ductwork, and coil requirements.
Rebates: verify the exact combination
Cold-climate ENERGY STAR certification may be relevant for certain financial assistance programs, but it does not automatically guarantee a specific amount.
Eligibility generally depends on:
- the model combination;
- the certification number;
- the recognized capacity;
- the purchase date;
- the installation date;
- the type of building;
- the rules of the program in effect.
We recommend keeping the quote, detailed invoice, serial numbers, and installation documents.
Central-Elios Warranty
The documentation lists a limited one-year warranty on parts and a five-year warranty on the compressor and indoor coil. Optional ten-year protections are also indicated for parts and labour, with the latter provided by a third party.
The conditions must be confirmed at the time of purchase, particularly regarding registration and exclusions.
Recommended maintenance after installation
To maintain the performance of this ELIOS electric furnace, we recommend:
- to check the filter regularly;
- to keep the air returns clear;
- to watch for signs of water;
- to note any unusual noise;
- not to store objects in front of the panels;
- to have the drain inspected;
- to have the electrical connections checked periodically;
- to request service when an error code appears.
A clogged filter remains one of the most common causes of reduced airflow in a central system.
An AirGreen installation tailored to Verchères and the South Shore
This ELIOS Central-Elios R454B electric furnace installation in Verchères demonstrates the importance of thoughtful mechanical integration.
The new unit had to work with a large existing network, a substantial return-air cabinet, refrigerant lines, a drain, and several controls. Every connection had to be organized without compromising airflow or service access.
At AirGreen, we install central heat pumps and electric furnaces in Verchères, Longueuil, and throughout the South Shore, as well as in Montréal, Laval, and throughout the North Shore.
Our approach is to address the entire system: indoor unit, outdoor unit, ductwork, electrical, drainage, filtration, and controls. This coordination is what makes it possible to achieve a reliable, quiet HVAC installation that is truly suited to the building.