Does my Toronto home HRV need a condensate pump or can it drain by gravity?

Most HRVs installed in Toronto homes can drain by gravity, but whether that's practical depends entirely on where your unit is located relative to a floor drain — and in many GTA basements, a condensate pump is the smarter, more reliable choice.

HRVs produce condensate year-round, but especially during Toronto winters when extremely cold outdoor air (-15 to -20°C) meets warm, humid exhaust air inside the heat exchanger core. That temperature differential causes significant moisture to condense out of the exhaust stream. A properly sized HRV running continuously in a GTA home can produce anywhere from 1 to 4 litres of condensate per day during peak winter operation — enough that drainage is not optional, it's essential. A blocked or missing drain line will cause the unit to flood, damage the core, and potentially leak onto your mechanical room floor.

Gravity drainage works when your HRV is mounted at a height that allows a continuous downward slope (minimum ¼ inch per foot) from the drain port to a nearby floor drain, utility sink, or condensate drain. The drain line should be ¾-inch ID tubing, kept as short and straight as possible, and must maintain that slope throughout its entire run — any low spots will trap water and eventually block. If your floor drain is within 3 to 5 feet of the HRV and sits lower than the unit's drain port, gravity is perfectly adequate and the simpler solution. Many GTA homes with the HRV mounted on a wall bracket directly above a laundry sink or floor drain work exactly this way without any issues.

A condensate pump becomes necessary when there's no floor drain nearby, when the HRV is mounted in a location where achieving a continuous downward slope is impossible (common in finished basements or utility rooms where the drain is across the room or on the other side of a wall), or when the unit is mounted low enough that gravity drainage simply won't reach any drain without running the line uphill at some point. Condensate pumps for HRVs are inexpensive — typically $60 to $150 for the pump itself — and a contractor can install one in under an hour. Look for a pump with a safety float switch that will shut the HRV down if the reservoir fills up due to a blockage, preventing overflow damage.

GTA-Specific Considerations Worth Knowing

Toronto's cold winters mean your HRV will go through defrost cycles — the unit temporarily reverses or reduces airflow to prevent the core from freezing. During defrost, condensate production spikes briefly. If your drain line has any sag or partial blockage, defrost cycles are often when overflow problems first appear. Check your drain line every fall before heating season.

Also worth noting: older GTA homes (pre-1980s) often have floor drains in the mechanical room that are infrequently used and may have dried-out P-traps. A dry P-trap allows sewer gases into your home. If your HRV drains into a floor drain, pour a litre of water into that drain every few months to keep the trap wet, or install a trap primer.

If your HRV drain line runs through an unheated space — even a short section through an exterior wall chase — insulate it. A frozen condensate line in January is a common service call in the GTA, and it's entirely preventable.

A licensed HVAC contractor should confirm your drain configuration when the HRV is installed or serviced. If you're unsure whether your current setup has adequate slope or whether your drain line is partially blocked, that's worth having checked during your annual HRV maintenance visit — which should include cleaning the core, checking filters, and verifying balanced airflow.

Need help finding an HRV installation or service contractor in the GTA? Toronto Ductwork can match you with a local ventilation professional through the Toronto Construction Network — browse the directory at torontoconstructionnetwork.com/directory?trade=hvac.