HRV and ERV Ventilation Systems: Which Does Your Home Need?

For most Hamilton homes, the answer is an HRV. Both systems bring in fresh air while recovering energy from the air they exhaust — the difference is that an ERV also transfers moisture. In Ontario’s cold, dry winters that moisture retention usually works against you, and since January 2025 the Building Code requires one or the other in every new home.

Key Takeaways

• HRV = Heat Recovery Ventilator. Transfers heat only. ERV = Energy Recovery Ventilator. Transfers heat and moisture.
• For most Hamilton homes: an HRV. Our winters are cold and dry, and an ERV’s moisture retention can push a tight home into over-humidification and window condensation.
• An ERV makes sense in very tight, very well-insulated builds (ICF, Passive House) where winter indoor humidity runs chronically low, or if you run AC heavily all summer.
• It’s not optional in new builds. Since January 1, 2025, OBC Section 9.32 requires heat or energy recovery in every new Ontario home, and your permit needs a ventilation design summary.
• Neither replaces your HVAC. An HRV or ERV works alongside your furnace, heat pump or AC — it doesn’t heat or cool your home.
• Cost: roughly $1,500–$3,500 tied into existing furnace ductwork, or $4,500–$6,500 for a fully ducted system with proper commissioning.

What Do HRV and ERV Stand For?

HRV stands for Heat Recovery Ventilator. It continuously exhausts stale indoor air and supplies an equal amount of fresh outdoor air, using a heat exchanger to transfer heat between the two streams so you don’t throw away the warmth you paid for. It transfers heat only.

ERV stands for Energy Recovery Ventilator. It does the same job, but its core transfers both heat and moisture. In winter it holds some indoor humidity back inside; in summer it strips some humidity out of the incoming air.

That’s the entire difference. Same box, same ducts, same purpose — one moves moisture, one doesn’t.

Both are sometimes called air exchangers, and both are balanced ventilation systems: they supply and exhaust equal volumes of air simultaneously, so your home is neither pressurized nor depressurized. The two air streams pass through the core on opposite sides of a barrier and never mix.

How Does an HRV Work?

An HRV pulls stale air from where it’s generated — bathrooms, kitchen, laundry — and pushes it through a heat exchanger core on its way outside. Fresh outdoor air passes through the same core on the other side of a plate barrier, picking up heat from the outgoing stream before it’s delivered to bedrooms and living spaces.

In January, that means outdoor air at -10°C arrives already substantially pre-warmed, so your furnace isn’t heating it from scratch. The two streams never touch; only heat crosses the barrier.

Because warm, moist indoor air meets a cold surface inside the core, HRVs produce condensate. That’s why they have a drain pan and a drain connection, and why in deep cold they run periodic defrost cycles.

How Does an ERV Work?

An ERV is mechanically identical, but its core is built from a moisture-permeable material rather than a solid plate. Heat crosses the barrier, and so does water vapour.

In winter, the outgoing air is more humid than the incoming air, so the core transfers some of that moisture back into the fresh air — keeping indoor humidity from dropping as far as it otherwise would.

In summer, the direction reverses. Incoming outdoor air is more humid than the conditioned air leaving your home, so the core moves moisture out of the incoming stream — meaning your air conditioner has less water to pull out of the air.

HRV vs ERV: The Key Difference

An HRV removes indoor moisture along with stale air. An ERV keeps some of it.

That single distinction decides everything else. It’s not about which is better built or more efficient — a good HRV and a good ERV are the same machine with a different core. The question is only whether your home has too much winter humidity or too little.

Which Should You Choose in Hamilton?

For most Hamilton homes, an HRV is the right choice.

Here’s the reasoning. Southern Ontario winters are cold and dry. Meanwhile, a modern airtight home generates a lot of moisture indoors — showering, cooking, laundry, and simply breathing all add water vapour, and a tight envelope gives it nowhere to escape. The result is that most Ontario homes have too much humidity in winter, not too little. That’s what fogs your windows in January and what grows mould in the corners of exterior walls.

An HRV exhausts that excess moisture. An ERV holds onto it. In a tight Hamilton home, choosing an ERV to solve dry winter air often creates a condensation problem instead.

Choose an HRV if:

• You have a typical Hamilton home — anything from a century property to standard new construction
• You see condensation on your windows in winter
• You’ve had any mould or damp issues on exterior walls
• Your home is reasonably airtight, which describes most builds from the last 20 years
• You’re not sure — this is the safe default in this climate

Consider an ERV if:

• Your home is exceptionally tight and well insulated — ICF, Passive House, or a certified high-performance build — and your winter indoor humidity genuinely runs low
• You’re running a humidifier constantly all winter and still fighting dry air
• You run air conditioning heavily through a humid Hamilton summer and want to reduce the latent load on it
• A ventilation designer has run the numbers for your specific home and recommended one

The honest caveat: “my house feels dry in winter” is not by itself a reason to buy an ERV. In most Hamilton homes the cheaper and more reliable fix is an HRV plus a humidifier, which lets you control ventilation and humidity independently instead of coupling them together in one device. If you can’t decide, that combination is almost always the safer bet.

What the Ontario Building Code Requires

Since January 1, 2025, an HRV or ERV is effectively mandatory in every new Ontario home. Ontario harmonized its Building Code with the National Building Code on that date, and OBC 2024 Section 9.32 now requires mechanical ventilation with heat or energy recovery in all new residential construction. Skipping it is no longer a realistic compliance path.

This isn’t entirely new. Supplementary Standard SB-12 has required heat recovery in new Ontario homes since January 1, 2017. What changed in 2025 is how tightly it’s specified and documented.

What this means if you’re building or doing a major renovation:

• A Mechanical Ventilation Design Summary (MVDS) is required in your permit package. It follows CAN/CSA-F326 and documents your total ventilation capacity calculation, room-by-room supply and exhaust, the specific unit selected, and your SB-12 compliance path. Applications submitted without it get returned as incomplete.
• The unit has to be chosen before the permit goes in. “HRV to be determined” isn’t an acceptable entry. The MVDS needs the manufacturer, model number, capacity and certified performance data.
• Efficiency is measured at -25°C, not at room temperature. The Code specifies a minimum Sensible Recovery Efficiency (SRE) at -25°C. Manufacturers usually advertise SRE at 0°C or +5°C, and those headline numbers are meaningfully higher than cold-weather performance. The minimum threshold depends on your climate zone and which SB-12 path the home uses — commonly cited figures run from 55% to 65%. Confirm the number for your municipality and path rather than assuming.
• Exhaust minimums apply too: a principal kitchen exhaust of at least 100 CFM, and supplemental bathroom exhaust of at least 50 CFM per bathroom.

If your home is existing, none of this is retroactive. You are not required to install anything. But it’s worth knowing that the Code now treats balanced heat-recovery ventilation as the baseline for a healthy home, which is a reasonable signal for anyone weighing a retrofit.

Is an HRV a Replacement for Your HVAC System?

No. This is the most common misunderstanding about these systems, and it’s worth being blunt: an HRV or ERV does not heat or cool your home. It has no burner, no compressor and no refrigerant. It cannot replace a furnace, a heat pump or an air conditioner.

What it does is ventilate — swapping stale indoor air for fresh outdoor air without dumping your heating or cooling energy out the wall along with it. Your HVAC system conditions the air. Your HRV or ERV changes it.

The two are complementary, not alternatives. In a new Ontario build you need both, and the Code assumes both.

How HRVs and ERVs Work With Your HVAC

Once you have both, they help each other measurably.

Supporting your furnace. An HRV pre-heats incoming winter air using heat recovered from the air going out, so your furnace isn’t warming outdoor air from scratch. It runs less to reach the same temperature.

Complementing a heat pump. Heat pumps lose efficiency as it gets colder outside. Reducing the ventilation heat loss they have to make up for keeps the base temperature more stable and takes load off the unit exactly when it’s struggling most.

Helping your air conditioner. In a humid Hamilton July, an ERV reduces the moisture content of incoming air, which means your air conditioner spends less of its capacity wringing water out of the air and more of it actually cooling.

Extending equipment life. Pre-conditioned incoming air means less extreme swings for your main heating and cooling equipment, and less runtime overall.

Two installation approaches, and the difference matters:

• Simplified (furnace-tied). The unit shares your existing forced-air ductwork. Cheaper, faster, and usually requires the furnace blower to run continuously — which uses more electricity than a dedicated system.
• Fully ducted. Dedicated supply and exhaust ducts running to specific rooms. More expensive, better performance, and independent of your furnace running.

For a look at how these tie into your existing ducting, see our guides to air duct cleaning and indoor air quality.

What Goes Wrong With HRVs and ERVs

Most HRV complaints aren’t equipment failures. They’re installation and operation problems, and they’re common enough that they’re worth knowing about before you buy.

The homeowner turns it off. By far the most frequent one. The unit hums quietly in the basement, nobody explained what it does, and at some point someone flips it off to save electricity. An HRV is designed to run continuously at low speed — that’s how it removes moisture and pollutants as they’re generated. Switched off, it’s an expensive box.

Intake and exhaust placed too close together. If the fresh air intake sits near the exhaust outlet, a furnace flue, or a kitchen exhaust, the unit re-breathes what it just expelled. The Code specifies minimum separation distances, and this gets missed on real installs more often than it should. Ask your installer to confirm the clearances at the terminations.

It’s never balanced. Supply and exhaust airflows are supposed to be measured and adjusted after installation so they actually match. This step — commissioning — is what turns a correctly-specified unit into a correctly-performing one, and it’s the first thing cut when a quote gets sharpened. If a quote doesn’t mention balancing, ask why.

Filters never get changed. Every three to four months. A clogged filter chokes airflow and the system quietly stops delivering the ventilation rate it was designed around.

Undersized or crushed ductwork. Especially in retrofits, where ducts get threaded through whatever space exists. The unit is rated at a specific airflow; restrictive ducting means it never reaches it.

None of these show up as an error code. The system keeps running and simply doesn’t do its job — which is why the install matters more than the badge on the box.

How Much Does an HRV or ERV Cost in Ontario?

Published prices for HRV and ERV installation in Ontario vary wildly — you’ll see anywhere from $1,500 to $6,500 quoted as “typical.” Both numbers are real. They describe different jobs.

Operating cost is genuinely small. These units draw roughly 30–90 watts running continuously, which works out to something like $3–$10 per month at Ontario electricity rates. Filters need changing every three to four months.

On rebates: federal and provincial programs have offered meaningful money toward HRV and ERV installation, usually when bundled with envelope work or a heat pump and requiring pre- and post-installation energy audits. These programs change frequently and open and close without much warning — see our current rebates page or ask us what’s actually live before you count on anything.

These are planning ranges based on 2026 Ontario and GTA pricing. The number that matters for your home comes from a site visit.

Still Not Sure?

If you’re weighing an HRV or an ERV for a Hamilton home, the decision usually comes down to three things: how tight your home is, what your winter humidity actually does, and whether this is a new build or a retrofit. Contact us and we’ll walk through it with you — including telling you if the answer is the cheaper option.