Guide

HRV, ERV, Air Exchanger, Heat Pump: What's the Difference?

If you've recently bought a home or you're trying to make sense of your basement for the first time, this HVAC vocabulary can be discouraging. Here's a simple guide, written for a homeowner — not an engineer.

The Principle: Every Unit Does One Specific Job

Your home needs four things:

• To be heated in winter
• To be cooled in summer
• A continuous supply of fresh air
• To have moisture and pollutants removed

Different units handle these jobs. Some combine several, others don't.

The Furnace

This is the traditional heating unit. It burns gas (or uses electricity) to heat air, then a fan pushes that air through the ducts. It doesn't cool, doesn't ventilate, and only filters minimally. Typical lifespan: 15 to 25 years.

The Air Conditioner

Its job: cooling. It pulls heat out of the house and releases it outside via a coil and refrigerant. In a home with a furnace + AC setup, both share the same ducts and the same fan. The air conditioner doesn't heat.

The Heat Pump

This is the "2-in-1" unit: it both heats and cools. It's essentially an air conditioner that can run in reverse. Two main categories:

• Wall-mounted heat pump (mini-split): one or more heads mounted on walls, connected to an outdoor unit. No ducts needed. Ideal for condos and homes without a central system.
• Central heat pump: replaces the air conditioner in a ducted system. Often paired with a backup furnace for extreme cold.

The Air Exchanger

In a modern, well-sealed home, the air is too airtight to refresh itself. The air exchanger fixes that. It removes stale air (kitchen, bathroom, moisture) and replaces it with fresh air from outside. As the two streams pass by each other, they exchange heat — the incoming fresh air is pre-tempered, which avoids wasting heating energy.

HRV vs. ERV: The Real Difference

The terms HRV and ERV refer to two types of air exchangers:

• HRV (Heat Recovery Ventilator): recovers only the heat between the two air streams. It's the most common in Quebec.
• ERV (Energy Recovery Ventilator): recovers heat AND moisture. Useful in very dry or very humid climates, or in homes where indoor air gets too dry in winter.

In Quebec, the HRV is the default choice in most homes, but the ERV is gaining popularity in newer, tightly-sealed construction.

The Kitchen Hood and Bathroom Fan

These are not air exchangers. They only exhaust — they don't bring in replacement air. In a well-designed home, the air exchanger handles the replacement, while these spot fans handle peak moments (cooking, showering).

How It All Fits Together

A typical modern home has:

• A furnace or central heat pump to heat/cool
• An air exchanger (HRV or ERV) for ventilation
• A network of ducts that moves it all around
• A thermostat to control it all

What About Maintenance?

Every unit has its own needs:

• Furnace: annual inspection + periodic cleaning
• Heat pump and air conditioner: annual maintenance (filters, coils, drain)
• Air exchanger: annual cleaning (filters, core, motors)
• Ducts: cleaning every 3 to 7 years depending on use