Installing central air in a cold-climate home
An air conditioner installation sets an outdoor unit, an indoor coil or wall unit, refrigerant lines, a condensate drain and electrical supply, then tests the circuit. In a cold-climate home, the extra questions are duct capacity, drain freezing and where snow and ice will fall on the outdoor unit.
What type of air conditioner suits your home?
Most Canadian houses with a furnace use a split system: an outdoor condenser connected by refrigerant lines to a coil above the furnace, with the existing ducts carrying cool air. It is called central air. Houses without ducts, or with additions that are hard to reach, often use a ductless split air conditioner, where one outdoor unit serves one or more wall-mounted indoor units. Window and portable units need no installation to speak of and suit a single room.
Many air conditioners cool only. A heat pump is an air conditioner that can also run in reverse, which is why a house needing both new cooling and new heating may be better served by one. The comparison is in heat pump versus furnace, and planning heating and cooling together explains when to combine the work.
How is an air conditioner installed, step by step?
The installation process for central air runs in a fixed order.
- The installer checks the furnace blower, the ducts and the electrical panel to confirm they can support the new load.
- The evaporator coil goes into the supply plenum, with a sealed pan and a drain line.
- The outdoor unit is set on a level pad, clear of walls and shrubs.
- Refrigerant lines run between the two units and are insulated, sealed and pressure-tested.
- Electrical supply and a disconnect are wired in, and the thermostat is connected.
- The technician evacuates the lines, charges the refrigerant and measures airflow and temperatures.
A ductless installation follows the same refrigerant logic, but the indoor unit mounts high on a wall, and a small hole through the exterior wall carries the lines and the drain. Refrigerant work needs a certified technician, and electrical work needs a licensed electrician. Permits differ by province and municipality, so ask the contractor and confirm locally. The wider HVAC installation guide explains permits and commissioning.
What matters in a cold climate?
Winters shape a few decisions. The outdoor unit should sit where snow sliding off the roof and icicles will not hit it, and with enough clearance above the usual snow line. The condensate drain from the indoor coil should not run through an unheated space where it can freeze and back up in shoulder seasons. Ask where the drain ends and whether a pump is needed.
Duct capacity is the other issue. Ducts designed for winter heat flow, particularly in an older house, may be too small for the airflow that cooling needs, and the first sign is noise at the registers. Leaky ducts in an attic waste cooled air in summer. A blower door test or a duct check can show where the leakage is.
Timing helps too. Installers are busiest in the first hot weeks of summer, so booking in spring or early autumn gives more choice of dates and time to compare quotes.
How big should the air conditioner be?
Sizing should come from a cooling load calculation, which accounts for windows, sun exposure, insulation, air leakage and the people and appliances inside. Square footage alone misleads. An oversized unit cools too fast and shuts off before it removes much moisture, leaving the air cool but clammy and the unit switching on and off repeatedly. A slightly smaller unit that runs longer often feels better. The method behind this is explained in our guide to load calculations.
Efficiency is shown on the label as a seasonal energy efficiency ratio. A higher figure uses less electricity for the same cooling, but costs more to buy, so the benefit grows with the number of hot days you expect. Canadian summers are short in most regions, which makes the payback of top-tier models slower than in hot climates.
What should you ask before you sign?
Ask for a written quote with the make, model, capacity and efficiency, the coil and any duct changes, the electrical work, the drain, the permit and the warranty. Get at least three, and ask each contractor to show the sizing calculation. Check that the warranty covers parts and labour, and whether yearly service is required to keep it valid. If the furnace is also old, discuss replacing both, and see furnace installation for what that involves. Prices vary by region and year, and quotes decide.
Quick answers
How long does it take to install central air?
A straightforward installation with usable ducts often takes about a day. New duct work, electrical upgrades or a hard-to-reach outdoor unit location can make it longer.
Can I add air conditioning to a house with a furnace?
Usually yes. A coil goes above the furnace and an outdoor unit is added, but the ducts and blower must handle the cooling airflow, so the contractor should check first.
Do I need a permit for an air conditioner?
Often yes, especially where electrical work is involved, though rules differ by province and municipality. The licensed contractor normally knows the local requirements.
Is a ductless air conditioner better than central air?
Neither is better everywhere. Ductless units suit houses without ducts or single-zone needs, while central air uses the existing ducts to cool the whole house.