Facts checked Sept. 25, 2026
Winter guide 2026 · Greater Montréal
Your heat pump in winter: defrost, “smoke”, lukewarm air, snow and baseboards
Steam, lukewarm air, stops lasting a few minutes: in winter, a lot of what worries people is normal. Here’s what’s normal, what isn’t, and how to set your heat pump with your baseboards.
HeatingDefrost: 5 to 15 min depending on the manufacturer
30 to 90 minBetween two timer-based defrost cycles, depending on the unit (NRCan)
2 to 3 °CSet the baseboards below the heat pump, e.g. 21 and 18 or 19 °C (Hydro-Québec)
25 to 45 °CThe normal temperature of air blown by a heat pump (NRCan)
< 15 daysBelow -20 °C per winter, on average (Hydro-Québec)
-25 to -30 °CLimit for high-efficiency models (Hydro-Québec)
Up to 40 %In heating savings (Hydro-Québec)
25 %Even more if it’s poorly maintained (Hydro-Québec)
In brief
The short answer
- The “smoke” is defrost steam: normal, 5 to 15 minutes depending on the manufacturer.
- Lukewarm air is normal: a heat pump blows air between 25 and 45 °C (NRCan).
- The baseboards are set 2 to 3 °C below the heat pump, e.g. 21 and 18 or 19 °C (Hydro-Québec).
- Snow should be cleared by hand; ice on the coil melts during defrost.
- The mode: Heat mode, never Auto, with a constant temperature (Hydro-Québec).
- In extreme cold, the baseboards kick in to help: that’s by design, often starting at -10 to -15 °C (NRCan).
01 · The diagnosis
Is what you’re seeing normal?
Nine winter situations. Tap the one you’re seeing.
NormalAdjustAct
What you’re seeing: “Smoke” coming from outside
NormalIt’s water vapour, not smoke.
Why
During the defrost cycle, the unit sends hot gas into the outdoor coil. The frost melts and some of it evaporates in the cold air: that’s the cloud you see. Fujitsu, Samsung, Sharp and Senville describe this as normal in their manuals.
What to do
Nothing. The cloud disappears once the defrost cycle ends, usually after 5 to 15 min, depending on the manufacturer.
Call if
A burning smell, dark smoke or steam that won’t stop: shut off the unit and call us.
Source: Fujitsu, Samsung, Sharp and Senville manuals; NRCan (2025)
Length of a defrost cycle, per the manual
In minutes. During this time, no warm air: that’s intentional.
Sharp
≈ 5 to 10
Samsung
5 to 12
LG
≈ 15
Fujitsu
15 max.
0481216 min
Manuals: Sharp CU/CHU, Samsung Wind-Free 2.0, LG MFL70423003, Fujitsu 9387081046. Your model’s manual is the authority.
02 · The house, point by point
Nine points to know, outside and inside
Tap a number on the house, or a label below.
Point 1 of 9
The “smoke”
NormalWhat you’re seeing
A white cloud above the outdoor unit, for a few minutes.
Why
It's defrost vapour: frost melting on the warm coil.
What to do
Nothing. Call only if it smells burnt or the smoke is dark.
Source: Fujitsu, Samsung, Sharp, Senville manuals
03 · The defrost cycle
The defrost cycle, step by step
According to NRCan, a timer-based defrost cycle can start every 30, 60 or 90 minutes. Here’s what happens, and how long it lasts.
Step 2 of 4
The cycle reverses
A valve switches and sends hot gas to the outdoor coil. The fans stop so they don’t blow cold air at you.
What you see and hearA click, then a hiss. The indoor fan stops, the light blinks.
Defrost: the valve reverses the cycle. Hot gas goes to the outdoor coil; the fans stop.
Source: NRCan; Sharp, Fujitsu, LG manuals
Interval between two defrost cycles
Duration per the manual
01 h2 h3 h
HeatingDefrost
2 defrost cycles at most in 3 hours, 10 to 20 min without warm air
Sharp: about 5 to 10 min. With a timer-based defrost cycle at 60 minutes. A “demand” defrost cycle only starts if there’s frost: Hydro-Québec recommends it at purchase.
04 · Lukewarm air
Why the air feels lukewarm
Three temperatures to compare. Source: NRCan, December 2025.
25 to 45 °C
Lots of air, less hot
NRCan: an air-source heat pump blows a large volume of air, usually between 25 and 45 °C. On your hand, it feels lukewarm. In the room, it heats.
Simple test: check the thermostat, not your hand. If the room reaches the set point, the heat pump is doing its job.
05 · The setting
Heat pump and baseboards: the right gap
21 and 20 °C? That’s too close, according to Hydro-Québec. Try your own settings.
Heat pump
21°C
It heats first. Hydro-Québec suggests about 21 °C.
Baseboards
20°C
They kick in during extreme cold. Hydro-Québec: 2 to 3 °C lower.
Gap: 1 °C
Gap too tightWith a 1 °C gap, the baseboards kick in as soon as the room cools a little and take over from the heat pump. Hydro-Québec recommends 2 to 3 °C.
On Rate Flex D? About 2 hours before a peak event, raise it 1 to 3 °C; during the event, lower it 2 to 4 °C, especially the baseboards in unoccupied rooms (Hydro-Québec).
06 · Your day
Choose a winter day
Five typical days. Slide the time to see what’s happening at home.
Flex D peak · -18 °C, 2 eventsTimer-based defrost:
Heat pump
Defrost cycles
Baseboards
Flex D peak
You
Time: 7 a.m.
0 h3 h6 h9 h12 h15 h18 h21 h
Defrost possible (at most 24 per day)Baseboards possibleBaseboards oftenBaseboards loweredPreheatingPeak eventTo do
At 7 a.m., what’s happening
- The heat pump heats continuously, in Heat mode.
- A defrost cycle may start this hour: the fans stop for a few minutes and steam rises outside.
- Peak event: each kWh costs 46.463¢ on Rate Flex D.
What you do
- Lower the temperature by 2 to 4 °C, especially the baseboards in unoccupied rooms (Hydro-Québec).
Illustration: the ranges come from the sources (NRCan for defrost cycles and backup heat, Hydro-Québec for peaks). Your unit may defrost less often, especially if it defrosts on demand.
07 · Flex D peak events
A peak costs a lot. Preheat.
On Rate Flex D, from Dec. 1 to March 31, a kWh during an event costs about 5 times more than outside one.
12 kWh
2 kWh40 kWh
What the house uses from 6–10 a.m. or 4–8 p.m. during an event.
2 hours before+1 to 3 °C
Preheat the house.
During-2 to 4 °C
Especially the baseboards in unoccupied rooms.
AfterBack
Go back to your usual setting.
Hydro-Québec's recipe. Example from its page: 22.5 °C two hours before, 20 °C during, 21 °C after.
What these kWh cost
$5.58
During a peak event, on Rate Flex D (46.463 ¢/kWh).
Every kWh shifted out of peakabout 5 times cheaper
Difference for these kWh$4.48
For illustration, taxes and access fees excluded. Rates in effect April 1, 2026. Off-peak, Flex D bills 4.886 ¢ for the first 40 kWh of the day.
Winter rates at a glance (in effect April 1, 2026)
First 40 kWh of the dayBeyond that
Rate D (year-round)7.065 ¢/kWh11.142 ¢/kWh
Flex D, winter, outside an event4.886 ¢/kWh9.103 ¢/kWh
Flex D, during an event46.463 ¢/kWh46.463 ¢/kWh
Access fee (D and Flex D)46.154 ¢ per day
Flex D eventsDec. 1 to March 31 · 6–10 a.m. and 4–8 p.m.Notice before 3 p.m. the day before · 120 h max. per winter
Source: Hydro-Québec, Electricity rates in effect April 1, 2026; Régie de l'énergie, D-2026-033.
08 · Deep cold
How far does your heat pump heat?
Slide the temperature: what the heat pump does, and when the baseboard heaters take over.
Outdoor temperature
−15 °C
-30-25-15-100+10 °C
Baseboards help more often
A cold-climate model still heats: the Gree Extrême 12,000 has a COP of 1.91 at -15 °C (ENERGY STAR), meaning 1.91 kWh of heat for 1 kWh of electricity. A baseboard gives 1 for 1.
< 15 daysbelow -20 °C per winter on average, in southern and central Québec (Hydro-Québec).
Heat produced per 1 kWh of electricity
The coefficient of performance (COP). The green line follows the temperature chosen above.
Heat pump at 8 °C
2.0 to 5.4
Heat pump at -8 °C
1.1 to 3.7
Gree Extrême 12,000 at -15 °C
1.91
Electric baseboard heater
1
0123456
NRCan (Dec. 2025) for the 8 and -8 °C ranges; ENERGY STAR (AHRI 9944776, Sept. 24, 2026) for the Gree Extrême. A baseboard heater converts electricity to heat at 1 to 1; Hydro-Québec: a heat pump can use up to 3 times less for the same heat.
09 · Snow
Snow and ice: the right height
A unit buried after every storm is usually mounted too low. Enter the usual snow depth where you live.
40 cm
0120 cm
Bottom of the unit, at minimum
Sharp: 10 in. (25.4 cm) above average accumulation65.4 cm
Senville: above the accumulation, 18 in. (46 cm) minimummore than 46 cm
Your model's manual is the final word. These two examples come from the Sharp and Senville manuals.
Not under the roof edge
Dripping water freezes on the unit. Otherwise, an approved gutter or drip deflector.
NEEPWall bracket if possible
The NEEP guide prefers it when the wall allows.
NEEPDrainage away from walkways
Defrost water refreezes and makes the ground slippery.
NEEPNever covered while running
No cover or tarp on a running unit: the grille must stay clear.
Fujitsu and Samsung manualsAfter a storm: four things to do
No special tool needed. Above all, no scraper.
Wait out the storm. No need to go out in the middle of the night: the heat pump keeps heating and defrosts on its own. Clear it once it's safe to do so.
10 · Your brand
What your brand's manual says
Six brands we sell and install. Defrost duration, indicator lights, filters, height: pick yours.
Sharp: what the manual says
Defrost durationAbout 5 to 10 min
During defrostIndoor and outdoor fans stopped
Indicator lightOperation flashes slowly
Before warm air returns2 to 5 min
FiltersMaintenance alert after 720 hours
Height above the snowAt least 10 in. (254 mm) above average accumulation
Minimum temperature-30 °C (some models -27 °C)
Manual consulted
Sharp owner's manual, CU/CHU series
Each series has its own manual. Your model's manual is the final word.
See Sharp heat pumps11 · Month by month
Your heat pump's winter, October to April
What to do each month, with the Flex D period dates.
December
Peak period begins
- Under Rate Flex D, the winter period runs from Dec. 1 to March 31.
- Possible events from 6–10 a.m. and 4–8 p.m., announced before 3 p.m. the day before.
- Excluded: Dec. 24, 25, 26 and 31.
- After every snowfall, clear the unit by hand.
12 · Before the first freeze
Nine checks before winter
Check them off as you go. Nothing is sent: it's your own list.
0 %9 items left to check.
Book a wall-mounted heat pump cleaningSomething that won't clear up? Mention it to the technician.
13 · Test yourself
Normal or not? True or false?
Two short games. Every answer comes with an explanation.
Answer all 8 situations0 correct out of 0
1
A white cloud rises from the outdoor unit for 5 minutes.
2
A burnt smell and grey smoke inside the house.
3
The indoor fan stops and the indicator light flashes slowly.
4
The outdoor unit is buried in snow up to the grilles.
5
The air comes out at about 35 °C.
6
At -2 °C, the baseboard heaters run all afternoon.
7
A click, a hiss, then silence.
8
In Auto mode, it blows cold air on a winter morning.
14 · The summary table
The whole winter in one table
Nine situations, their verdict and what to do. Keep it handy.
What you’re seeingVerdictBenchmarkWhat to do
“Smoke” coming from outsideNormal5 to 15 minNothing: it passes
The air is lukewarmNormal25 to 45 °CJudge it by the thermostat
It stops, the indicator light blinksNormal5 to 15 minWait it out
The fan is slow to startNormal2 to 5 minLet it start on its own
Click, hiss, or crackleNormalStart and end of defrostNothing, if it follows a defrost cycle
Snow or ice on the unitActUnit clearBroom, by hand
Water runs and freezes underneathActSloped drainageClear walkway
The baseboard heaters run nonstopAdjust2 to 3 °C lowerE.g., 21 and 18 or 19 °C
It's not enough in deep cold anymoreNormalBackup from -10 to -15 °CBaseboard heaters as backup
Sources: manufacturer manuals, NRCan, Hydro-Québec, NEEP (details in section 01 and at the bottom of the page).
15 · FAQ
Your questions about heat pumps in winter
Twelve short answers, with their sources. Search a word, with or without accents.
Why does my heat pump “smoke” in winter?
It’s not smoke, it’s water vapour. During the defrost cycle, the unit heats its outdoor coil: the frost melts and some of it evaporates in the cold air. Fujitsu, Samsung, Sharp and Senville manuals describe this cloud as normal. A burning smell or dark smoke, on the other hand, calls for shutting it off and calling us.
AirGreen · Greater Montréal
Not sure about your heat pump this winter? Talk to our technicians.
We install, clean and repair wall-mounted heat pumps across Greater Montréal. Tell us what you're seeing, by phone or through the form.
RBQ licence 5645-9605-01Subcategories 15.8, 15.10 and 16
Free on-site estimateFor a new installation
Quote within 24 hIn writing, after the estimate
Cleaning and repairA service page for every symptom on this page
Sources verified Sept. 25, 2026
- Hydro-Québec, “How to use your heat pump in winter to maximize your savings” (accessed Sept. 25, 2026)
- Hydro-Québec, “Heat pump: seven tips to save all year” (accessed Sept. 25, 2026)
- Hydro-Québec, LogisVert factsheet “Heat pump,” 2025G386F, rev. 07/2026
- Hydro-Québec, Electricity rates in effect April 1, 2026 (Rates D and Flex D); Régie de l'énergie, D-2026-033
- Hydro-Québec, Rate Flex D tips (preheating before a peak event)
- Hydro-Québec, “Heating tips” and “Seven things to consider when buying a heat pump”
- NRCan, “Heating and cooling with a heat pump,” modified Dec. 24, 2025
- NRCan, “Heat pumps” (Greener Homes), modified Aug. 4, 2026
- NEEP, “Guide to Installing Air-Source Heat Pumps in Cold Climates”
- Manuals: Sharp (CU/CHU series), Samsung Wind-Free 2.0, LG MFL70423003, Fujitsu 9387081046, Gree Sapphire and Vireo Gen3 (2022), Senville Aura
- ENERGY STAR, heat pump certification data (Gree Extrême 12,000, AHRI 9944776), Sept. 24, 2026
Durations, temperatures and heights come from the sources cited; your model's manual is the final word. Flex D amounts are for illustration only; only Hydro-Québec sets your bill.
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