These Installation Details Amateur Technicians Consistently Ignore (And That Cost Montrealers a Lot of Money)

Why a poorly done HVAC installation can cost thousands in the long run

In Montréal, as well as in Laval, Longueuil, on the North Shore and South Shore, demand for air conditioning and heating systems is on the rise. While more and more Montrealers are investing in wall-mounted heat pumps, central air conditioners, or mini-splits, too many of these systems are still being installed by uncertified technicians, often with no attention to detail. The result? Loss of efficiency, early breakdowns, shorter lifespan, and ultimately, unnecessary costs.

At AirGreen, we’ve fixed hundreds of botched or incomplete installations. Here are the critical details a professional installer would never overlook, but that we constantly find ignored in low-cost or uncertified installations.

Improper slope on the condensate drain line

One of the most common problems: a drain pipe that isn’t sloped properly, preventing condensed water from draining as it should. Too often, the pipe is:

• Installed flat, with no minimum slope;

• Crushed behind a wall;

• Connected without a trap or clean-out.

Consequences:

• Standing water buildup;

• Indoor leaks, sometimes months after installation;

• Growth of mold inside walls or ceilings.

At AirGreen, we follow strict slope and access standards and pressure-test drainage systems after installation.

Refrigerant lines pulled too tight or poorly insulated

Another common amateur mistake: stretching refrigerant lines to the limit, ignoring manufacturer-specified bend radii.

This leads to:

• Invisible micro-leaks at the elbows;

• A gradual drop in performance;

• Premature compressor wear.

Additionally, insulation is often neglected. Thin or poorly applied foam causes:

• Thermal losses;

• Exterior condensation;

• Freezing risk in winter.

No vibration-dampening support for outdoor units

In Montréal, the climate brings major temperature fluctuations and freeze/thaw cycles. Installing a heat pump’s outdoor unit directly on a concrete slab without vibration pads is an expensive mistake.

Impacts:

• Loud vibrations transmitted into the building;

• Cracking concrete over time;

• Shortened mechanical life span of the unit.

At AirGreen, we always install reinforced anti-vibration supports, designed to absorb mechanical shocks while allowing snow and water drainage.

Poorly calculated BTU output

One of the biggest traps in “budget” quotes: offering a unit that’s either too small or too large, without considering:

• The actual square footage and volume of the space;

• The sun exposure of the home;

• Existing insulation quality;

• Appliances and cooking equipment already generating heat.

Oversizing causes:

• Short cycling, wearing out the compressor;

• An uncomfortable feeling of cold damp air.

Undersizing results in:

• A system that runs continuously without ever reaching the target temperature;

• Excessive power usage.

Every AirGreen installation includes a full thermal evaluation, with precise calculations of required BTU capacity.

Poorly sealed wall penetrations

It’s common to see rushed installers skip proper sealing around wall penetrations. This leads to:

• Air leaks, hot or cold;

• Moisture intrusion into the walls;

• Development of mold and air barrier degradation.

We always use weather-resistant insulating materials and professional expanding sealants to ensure full airtightness.

Real-life case in Ahuntsic: 4 errors in one installation

“An installer offered me a wall-mounted heat pump at a bargain price. Three months later, water was leaking into my kitchen. AirGreen stepped in: the drain was horizontal, the pipes were uninsulated, the outdoor unit had no support, and the BTU was too low. They redid everything properly, and since then, it’s been flawless.”
— Caroline R., Ahuntsic

How to avoid these mistakes from the start?

Here are AirGreen’s recommendations before any HVAC installation in Montréal or surrounding areas:

• Require a valid RBQ license;

• Ask for an on-site evaluation before receiving a quote;

• Make sure the quote includes labour, materials, supports, and sealants;

• Be cautious of offers promising installation “in 2 hours.”

Why choose AirGreen?

Our commitments:

• Certified installers with years of field experience;

• Use of premium materials — no compromises;

• Strict compliance with manufacturer technical standards;

• Fast, reliable after-sales service, with parts available locally.

We serve the Greater Montréal area, including Laval, Longueuil, the North Shore, and the South Shore, for both residential and commercial projects.

Conclusion: short-term savings can lead to long-term costs

A poorly executed HVAC installation often looks fine at first. But it almost always leads to repairs, higher costs, and frustration. At AirGreen, we prioritize rigor, transparency, and technical expertise to ensure your investment is long-lasting and worthwhile.

Before accepting a questionable installation, contact us for a professional evaluation. A proper installation is the key to performance, comfort, and peace of mind.