Tag: moisture

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Cottage Life

Cottage Q&A: Pros and cons of running a furnace fan

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What are the pros and cons of running a furnace fan when away from the cottage? I am looking to save on hydro but I worry about moisture buildup.—Ruta Valaitis, via email

Well, there’s really just the one major pro and the one major con. And you already know what they are. “Air circulation is almost always a good idea, but a furnace fan can be expensive,” says Don Fugler, an Ottawa building scientist. “Depending on the fan motor and its setting, a circulation fan can use from 300 to 1,500 watts continuously.” (That said, it might be possible for you to make some adjustments to the unit, for example, replacing the fan motor with one that’s more efficient.) 

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But, “here is one interesting fact,” says Fugler. “If you heat your cottage with electricity during the winter to keep it above freezing, the furnace fan electricity use will not add greatly to that cost. Those 300 to 1,500 watts of fan electricity will simply offset 300 to 1,500 watts of electric heating.” (This is assuming that your furnace runs on electricity, not natural gas, oil, or propane.)

So, if you regularly visit your cottage in the winter, it might be beneficial to leave the heat on low when you’re away—Fugler suggests at least 5°C—along with running the fan. Bonus: this’ll probably make the cottage visit more pleasant, certainly when you first arrive. “If you let the cottage go down to -10°C, or whatever ambient temperature is in the vicinity, it will take all weekend for the surfaces and bedding to get up to comfortable temperatures,” says Fugler.

Have you had moisture problems before? “Existing conditions are the best indication of the need for more ventilation,” says Fugler. “When people ask if they should add more attic vents, I ask if they have had to replace roof boards or sheathing due to rot.”

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Air circulation will help to minimize localized moisture problems, says Fugler—for example, window condensation that drips down onto the windowsill. But no fan in the universe will prevent moisture buildup if water is getting into the cottage from, say, leaks or a high water table. You’d want to resolve those problems before trying any ventilation solutions.

This article was originally published in the Winter 2022 issue of Cottage Life.

Got a question for Cottage Q&A? Send it to answers@cottagelife.com.

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Cottage Life

Cottage Q&A: Should we heat our empty cottage?

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We live permanently at our four-season cottage, a well-insulated Viceroy home with forced-air propane heating and back-up electric baseboard heaters in the basement. We want to go south this winter for six to eight weeks. (I will drain the water from the pipes.) What is the ideal temperature to keep the home at during this period? I was thinking about 8°C to 10°C, but I have heard that this could cause dampness and eventually lead to mould.—Michael Oke, via email

Don Fugler, an independent building researcher in Ottawa, thinks that temperature is reasonable for the length of winter absence you’re describing. “If there’s a ventilation system—even a small bathroom fan that’s designed for continuous usage—running it would be helpful in keeping the interior dry,” he says. He also recommends that you leave interior curtains and blinds open. “They can create micro-environments that may lead to condensation. I like to leave the windows without coverings, and leave all the interior doors open, including the door to the basement.”

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This should keep the mould away, assuming your place doesn’t have an existing moisture problem (from, for example, water that’s not being properly diverted away from the cottage or cracks in the foundation). You probably know already if you’ve got a damp basement. Indicators include a musty smell and finding water-damaged belongings. “The inability to store cardboard boxes is a strong sign,” says Fugler.

Okay, so heating the cottage while you’re gone is a good idea. But if you’re going to do that, is draining the pipes in fact necessary? Well, no. “Temperature wise, at anything above zero, pipes are not going to freeze,” says Shawn Groulx of Express Plumbing and Heating in Red Deer, Alta. That said, “it’s still a good practice.”

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If you don’t drain the pipes, he recommends that you shut off the main water valve and open the taps. It’s not only cold temperatures that can mess with your plumbing, says Groulx. A tiny problem could turn into a catastrophic, gushing leak while you’re away. Holy basement dampness!

Got a question for Cottage Q&A? Send it to answers@cottagelife.com.

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Cottage Life

Cottage Q&A: Wet windowsill fix

By mady70/Shutterstock

When we checked on our cottage this winter, I noticed that condensation had puddled on the windowsills. Can we prevent this from happening? The cottage is not heated through the winter, and we do not regularly use it.—Margaret Robinson, via email

You know the science: if warm, humid air inside the cabin meets the cooler surface of a window in winter, condensation forms on the glass.

It’s possible that the air inside warmed up because of the sun. “You could envision how passive solar heating of a cottage could create moisture deposition problems inside,” says Don Fugler, a building scientist in Ottawa.

But, more likely, says Darrell Paul, the managing director of Qualistat Building Performance Consultants in Olds, Alta., is that the condensation is an after-effect of the last time you were at the cottage—when we assume you turned on the heat and then engaged in other humidity-producing behaviours: cooking, showering, and breathing.

In either case, the best way to prevent condensation is to increase ventilation to the cottage. Simple enough while you’re there. Trickier while you’re not. Almost anything that allows outside air into the cottage will help; the problem is “How do you do that safely, in a way that animals won’t get in?” says Fugler. If your chimney is covered by a pest screen, you could open the damper; you could leave a few windows partially open, covered with hardware cloth; you could also install new openings in the cottage, such as fresh air-intake ducts.

If you have reliable power, a small fan—either rated for continuous use or triggered by a humidistat (it responds to relative humidity)—is an alternative.

This article was originally published in the Winter 2017 issue of Cottage Life magazine.

Got a question for Cottage Q&A? Send it to answers@cottagelife.com.