Some heating advice gets repeated so often that it stops sounding like a claim and starts sounding like common sense. A few of those beliefs are quietly expensive. Here are the five we hear most often in Montreal and Laval homes, and what is actually true.
Myth 1: Adjusting the thermostat often makes you more comfortable
The truth. Nudging the thermostat up and down does not reliably make a house more comfortable, and it usually adds to what you pay. A thermostat is a target, not a throttle. Your system produces heat at one rate whether you ask it for 21 or for 26, so raising the setting does not speed anything up. It simply keeps the system running past the point where you were already comfortable.
Heat pumps in particular do their best work holding a steady temperature over long, gentle runs, and frequent changes force them into exactly the catch-up cycles they handle least efficiently. If a room is slow to reach temperature, the cause is usually airflow, sizing or insulation rather than the number on the wall. Our guide to optimizing a central heat pump covers the settings that genuinely make a difference.
Myth 2: Maintenance is not necessary as long as your HVAC system is working
The truth. Equipment rarely fails suddenly. It degrades. A clogged filter, a dirty coil or a tired fan makes the system work harder for months before anything actually stops, and you pay for that extra effort on every bill in the meantime. Regular servicing is what keeps the equipment running well and extends its life.
Skipping maintenance can also cost you the warranty. Most manufacturers expect documented annual servicing, and a claim can be refused without those records. We recommend two visits a year, one before the cooling season and one before the heating season. What normal HVAC maintenance includes sets out what each visit covers, and how to prepare your furnace for winter deals with the heating side specifically.
Myth 3: A heat pump does not work below −15 °C
The truth. Heat pumps certified ENERGY STAR Cold Climate are built to keep heating in temperatures down around −30 °C. This belief comes from older equipment and has not reflected what the technology does for years.
What genuinely changes as it gets colder is capacity rather than whether the unit runs at all: the lower the temperature, the less heat it can deliver. That is why correct sizing and a sensible backup plan matter so much here. Is a central heat pump enough for a Quebec winter? looks at where the real limits sit, and if you already own a furnace, a bi-energy setup pairs the two so each runs when it makes the most sense.
Myth 4: The model of heat pump is what matters most
The truth. A badly installed heat pump never delivers its rated performance, whatever the badge on the front says. Manufacturers rate their equipment installed correctly, and correct installation is the only condition under which you ever see those numbers.
The work that decides it is mostly invisible once the job is done: a heat load calculation rather than a guess, ductwork sized and sealed properly, a measured refrigerant charge, and a commissioning check at the end. Get those wrong and a premium unit underperforms an ordinary one that was installed properly. It is also why two quotes naming the same brand can describe genuinely different jobs. How to choose an HVAC contractor covers the questions worth asking, and how a heat pump works explains what the equipment is actually doing.
Myth 5: A bigger system is better
The truth. A wrongly sized system hurts comfort, pushes up your electricity costs and can lead to expensive breakdowns. Oversizing feels like insurance, but a system too large for the house performs worse than one matched to it, every day rather than only at the extremes.
An oversized system reaches the set temperature quickly and shuts off, then starts again minutes later. That short cycling means it never settles into the long, steady run where it works best. In summer it chills the air before pulling any real moisture out, so the house ends up cold and clammy. In winter you get swings and cold corners instead of even heat. And because starting up is the hardest thing a compressor does, more cycles means more wear, bringing both the repairs and the replacement forward.
The answer is the same heat load calculation: what your house actually loses and gains, based on its size, insulation, windows, orientation and air leakage. It is not a rule of thumb per square foot, and it is not matching whatever was there before, because the old unit may well have been wrong too. Our central heat pump buyer’s guide explains how that calculation is done, and what type of air conditioner suits your home covers matching equipment to the space.
Still not sure?
Most of these myths survive because the truth takes a sentence longer to explain than the myth does. If you are weighing a decision and would rather have a straight answer about your own house than a general rule, get in touch. We work across Montreal and Laval, and we are just as happy to tell you when you do not need what you were about to buy.
