Basement Dehumidifier Freezing Up and How to Prevent Dehumidifier Icing Up

How can I prevent my Basement Dehumidifier from Freezing Up?

By Mark J. Donovan

Question: My basement dehumidifier kept freezing up this past spring and I have no idea why it happened. During the summer it has run fine. Do you have any thoughts on why a basement dehumidifier could freeze up?

Answer: A dehumidifier consists of a fan, a condenser, and heating and cooling coils. It is effectively an air conditioner, except that the heating and cooling coils are collocated in the same unit.

A basement dehumidifier works by drawing warm moist air into it and over the cooling coils. See this basement dehumidifier buying guide.

The moist warm air then condenses onto the coils and drips into a holding pan or out a drip hose. The cool dry air is then warmed by the heating coils back to the room temperature as it exits the dehumidifier.

The moist warm air then condenses onto the coils and drips into a holding pan or out a drip hose. The cool dry air is then warmed by the heating coils back to the room temperature as it exits the dehumidifier.

Dehumidifier in basement

A dehumidifier works best at warmer ambient temperatures and higher relative humidity levels. As the basement dehumidifier condenses the warm moist air, the water vapor generally produces enough heat to prevent the cooling coils from freezing up.

However when the ambient air temperature is cool, e.g. below 60o Fahrenheit, and/or the relatively humidity is below 45%, dehumidifier freeze up is possible. The risk of a basement dehumidifier icing up is increased if the cooling coils are covered in dirt and dust, which can frequently happen to a basement dehumidifier.

I suspect your particular basement dehumidifier freeze up situation was the result of too cool an ambient air temperature in the basement. Typically unheated basements are around 55o Fahrenheit during the winter/spring seasons. If the relatively humidity was also low then the chances of the basement dehumidifier freezing up were further enhanced.

Preventing Basement Dehumidifier Freeze Up

To prevent a basement dehumidifier icing up there are number of steps you can take.

First, cycle the basement dehumidifier off and on every few hours, or if the humidity is already low, then turn it off altogether.

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By turning the basement dehumidifier off periodically you can give the cooling coils a chance to warm up and melt any ice that may have formed on them, thus preventing a dehumidifier icing up problem.

Second, by raising the room temperature you can reduce the risk of ice formation in the basement dehumidifier.

Third, periodically clean the basement dehumidifier’s cooling coils and fins. By keeping them clean, water can more easily drip off of them and prevent the buildup of ice.

Finally, raise the basement dehumidifier up off the floor of the basement. Warm moist air has the tendency to rise and accumulate near the basement ceiling, whereas the cooler drier air falls and clings near the basement floor.

By raising the basement dehumidifier up off the floor, the dehumidifier can work more effectively and have a reduced risk of the dehumidifier freezing up.

Another solution, which will cost a lot more, but will reduce the amount of work on you basement dehumidifier as your basement will be drier, is to waterproof you basement. Waterproofing a basement’s walls and floor can dramatically reduce the amount of moisture entering your basement, thus reducing the amount of work required from your dehumidifier. Check out this article on options for waterproofing your basement walls and floor.

For more help on Basement Additions, see’s Basement Remodeling Bid sheet. The Basement Remodeling Bid Sheet will help ensure that your hire the right contractor so that your basement remodeling project is done correctly and you get the project finished on time and budget.

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