· By Diego Gómez
Do you need to run a basement dehumidifier in winter?
Many Canadian basements dry out once the furnace runs, but not all. How to tell if yours needs a dehumidifier in winter, and why cold basements are tricky.
In summer, the basement dehumidifier runs non-stop. Come November, many people unplug it and forget about it. That's often the right call, but not always.
Why most basements dry out in winter
Cold outdoor air holds very little moisture. Once the furnace is running, the air inside your home gets drier, and the basement usually follows. In many Canadian homes the problem flips: the main floors need a humidifier while the basement is fine on its own.
When you still need it
- Your hygrometer reads above about 50–60% in the basement even with the heat on.
- You dry laundry down there or have the washer and dryer in an unfinished space.
- There's a musty smell, damp patches on the foundation walls or water around the sump.
- A thaw or winter rain brings water in through cracks or window wells.
- The basement is finished with carpet and drywall against concrete walls, where moisture can hide.
The cold basement problem
Compressor dehumidifiers work best in warm rooms. In an unheated basement around 10–15 °C (50–60 °F) they pull out much less water and their coils can frost up. If yours is that cold, check the manual for the minimum operating temperature and auto-defrost, and consider adding a little heat. Remember that today's capacity figures use the DOE test at 65 °F (18 °C), so a cold basement will see less than the box says.
A simple winter routine
- Leave a hygrometer in the basement and check it weekly.
- Set the dehumidifier's humidistat to around 50% so it only runs when needed; with a drain hose you don't have to empty the tank.
- Keep it unplugged if humidity stays low, and plug it back in for the spring thaw.
Our picks are in basement dehumidifiers. For the right humidity on the rest of the floors, see what indoor humidity you should have in winter, and if your windows frost up, read condensation and frost on windows.
Recommended
Midea 22 pint (DOE) with WiFi
- 22 pints/day (DOE, 65 °F/60% RH)
- up to 1,500 sq ft
- 47 dBA
Energy Star dehumidifier with WiFi for small and medium basements.
KNKA 34 pint with drain hose
- 34 pints/day
- 37 dB, sleep mode
- drain hose, auto humidity, child lock
Quiet basement dehumidifier with a drain hose so you don't have to empty the tank.
Frigidaire 50 pint with WiFi
- 50 pints/day
- 2.7 gallons
- WiFi, continuous drain, washable filter
Big-name 50-pint unit for large or very damp basements, with continuous drainage.
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