How to Prepare Your HVAC System for a Metro Vancouver Heat Dome Event

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Why heat domes are hard on HVAC systems

Metro Vancouver homes and older HVAC equipment weren't originally designed with sustained extreme heat in mind, since our summers have historically been mild. During a heat dome, outdoor temperatures can stay elevated for days with little overnight cooldown, which means an air conditioner or heat pump runs almost continuously instead of cycling on and off. That constant runtime puts more strain on the compressor, coils, and electrical components than a typical summer day. A system that's been getting by on light use the rest of the year can be the one that struggles or shuts down when it's needed most.

Undersized systems, dirty filters, and clogged outdoor coils all reduce how efficiently a unit can move heat out of your home. When the system is already working at its limit just to keep up with normal conditions, a multi-day heat event doesn't leave much margin.

Steps to take before a heat dome hits

• Replace or clean your air filter — a clogged filter restricts airflow and makes the system work harder to cool the same space.
• Clean debris, leaves, and grass clippings off the outdoor condenser unit, and trim back plants so there's clear airflow on all sides.
• Check that indoor vents and returns aren't blocked by furniture, curtains, or rugs.
• Test the system on a cool day — run it for 20-30 minutes and confirm it's actually producing cold air and cycling normally.
• Check your thermostat batteries (if applicable) and confirm the schedule and settings are correct.
• Close blinds or curtains on south- and west-facing windows during the hottest part of the day to reduce heat load on the system.
• If you don't have cooling at all, or your only cooling is a portable unit, plan now — installation demand spikes hard once a heat warning is issued.

During the heat dome itself

Avoid setting the thermostat drastically lower than normal hoping the house will cool faster — it won't, and it just makes the system run longer without added benefit. Use ceiling or portable fans to help air circulate so the thermostat setting can stay a bit higher while the room still feels comfortable. If you have a heat pump, keep the outdoor unit's airflow clear of anything that could restrict it, since it's working at or near its peak capacity during these events.

If your system stops keeping up mid-event, don't wait — a small issue like a dirty coil or a low refrigerant charge that's manageable on a normal day can turn into a full breakdown under sustained heavy load.

When to call a professional

If your AC or heat pump is more than 10-15 years old, has needed repairs in past summers, or you're not confident it can handle several consecutive days of extreme heat, it's worth having it looked at before the season gets going rather than during a warning. CANRO offers diagnostic visits and a free written quote if repair or replacement makes sense — no guesswork, no pressure. If you're considering a new system, heat pump installations for a typical Metro Vancouver home generally run in the $6,000-$18,000+ range depending on size and configuration, and CleanBC or FortisBC rebate programs may apply — we can point you toward the current program details when we quote your job.

Frequently asked questions

Reviewed by the CANRO Heating & Cooling service team — July 07, 2026. Technical Safety BC gas licence LGA0043870 · boiler licence LBP0046450 · Red Seal certified · WorkSafeBC and liability insured · 4.9★ from 85+ Google reviews · serving Metro Vancouver since 1999 · (604) 359-1081.