A rooftop system in trouble
A client in Côte-des-Neiges , Montreal, recently contacted us for a service call regarding a Tosot wall-mounted heat pump installed on the roof of his building. This type of installation, typical of urban buildings with flat roofs, requires increased vigilance: direct exposure to the elements and dust can accelerate component wear.
The customer reported that the system was no longer producing heat despite the compressor appearing to be operating.
Diagnosis: Identify the cause of the lack of performance
Our technicians first carried out a complete analysis of the Tosot system :
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Checking the refrigerant using an electronic manifold.
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Checking the electronic card of the external module.
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Inspection of the fan and interior impeller to assess airflow.
The observation was clear:
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The refrigerant level was low , indicating a slow leak in the copper line .
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The outdoor condenser was covered with a thin layer of dust and debris, reducing heat exchange capacity.
These two factors explained the drastic decrease in the energy efficiency of the heat pump.
Intervention: leak detection and complete restoration of service
Our team undertook a three-step intervention:
1. Location of the leak
Using an electronic detector and a nitrogen tracer , we identified a micro-leak at the flare fitting connecting the liquid line to the Tosot compressor. This junction point, subject to vibration and heat, is often a common cause of refrigerant loss.
2. Repair and tightening
We replaced the flare fitting with a permanent solder (silver solder) to eliminate any risk of future leaks. New thermal insulation was then installed to protect the line from the sun and temperature fluctuations.
3. Cleaning and recharging the system
The condenser was thoroughly cleaned with a pH-neutral biodegradable product.
We then have:
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Pulled a complete vacuum from the system for 40 minutes.
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Recharged the circuit with the exact amount of R410A prescribed by Tosot.
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Checked the static pressure and discharge temperature .
Everything has been recalibrated to manufacturer specifications.
Performance testing and validation
After restarting:
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The Tosot compressor has resumed quiet and stable operation.
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Evaporation and condensation temperatures have stabilized at optimal values.
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The energy efficiency (COP) has returned to normal.
The customer immediately noticed a significant improvement in interior comfort .
The Importance of Preventive Maintenance of Rooftop Installations
Flat roof installations , like this one in Côte-des-Neiges, are particularly exposed:
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Dust, leaves and debris quickly accumulate in the coils.
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Extreme temperature variations (frost and direct radiation) put additional stress on joints and connections.
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Structural vibrations can cause microleaks.
At AirGreen, we recommend annual maintenance for this type of installation, including:
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Complete cleaning of the condenser and evaporator.
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Checking pressures and electrical currents.
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Visual inspection of refrigeration fittings and supports.
Final result
After our intervention:
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The leak has been permanently eliminated .
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The performance of the Tosot heat pump has been restored to 100%.
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The system is ready to face the heating and cooling seasons with efficiency.
The customer, delighted with the result, now benefits from a reliable, silent and energy-efficient system , perfectly adapted to its urban environment.
AirGreen: HVAC expertise in Montreal
Whether for a roof installation , a leak diagnosis , or the recommissioning of a Tosot wall-mounted heat pump , AirGreen is the trusted partner throughout Greater Montreal: Montreal, Laval, Longueuil, the North Shore and the South Shore .
Our interventions are always fast, precise and comply with the highest standards of the HVAC industry .