Leaking Bath Fans & Attic Rain

  • Home Owner Tips
  • Tuesday, January 11, 2022

Over the last few weeks, the cold temperatures have kept many of us indoors only to go out when necessary. Thankfully, the weather is forecasted to be in the plus temperatures for the next week, which will be a nice relief! With the temperatures rising, our Service & Warranty team wanted to provide some information regarding leaking bath fans and Attic Rain.

Attic Rain occurs during the winter months when extreme cold temperatures that last for extended periods of time are followed by warmer temperatures, which in turn start a rapid melting process wherever there is frost build up. Attic Rain occurs when high humid/warm air meets exterior cold air in attic spaces, creating crystallization and frost on the sheeting or roof trusses.

During the cold temperatures it’s very important that the humidity in your home is managed daily by turning on bathroom fans, hood fans, HRV exchange units ,and furnace fans throughout the day. New homes are built so tight and high efficiency furnaces are so efficient, that warm air will typically escape through light fixtures, pot lights, and attic hatches. As a result, Attic Rain can create water staining at your pot lights, light fixtures, or at any flat surface on the ceiling.

Please take take a look at our bulletin regarding the effects of High Humidity for more information.

Dripping Bath Fans

With warmer temperatures approaching, we anticipate we’ll receive many phone calls regarding dripping bathroom fans. During periods of cold weather, water vapour may condense or freeze in the exhaust venting of your home. During warming periods, this may result in moisture dripping back through the vent, and while this may seem worrisome, it is an acceptable occurrence.

Damage caused by dampness or condensation due to failure to maintain adequate ventilation and humidity is not considered a defect.

Below are some tips on how to prevent condensation in your home:

  1. Check the humidistat to ensure it is set to 10% – 20% depending on the temperature. You may be required to turn this off completely during cold temperatures.
  2. Leave your bath fans ON for at least 30 before and after baths and showers.
  3. To accelerate the drying of windows, turn all fans on (bathrooms, ventilation, and hood fan) for a few hours a day.
  4. If the bathroom fan is dripping, run the affected fan for 4-6 hours straight. You may need to run it continually for 24 hours to help reduce moisture.
  5. Turn the HRV system to the Vent setting and leave on day and night during colder temperatures. This will help circulate the air regularly. The ventilation setting is on your HRV Control Panel.
  6. Ensure that all blinds are pulled up, open, and drapes are pulled back.

These six things will help remove the condensation from your home and reduce the amount of humidity.

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