Cathedral ceiling fans and energy efficiency
RReyn
| Posted in Energy Efficiency and Durability on
Hi all,
I just moved in to a house with cathedral ceilings and a wood burning stove (insert) and trying to figure out how important a ceiling fan is. People say it will circulate heat down in the winter (if in reverse) but do folks have a sense of how substantial energy savings might be in gross ballpark percentage terms? Also, is it a benefit in the summer with central air and if so how much? Does the air movement get all the way down to cool in a meaningful way? Do you have to hang it low? Or can it be right at the top. I appreciate any wisdom any of you have to offer.
–Roger
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Replies
The problem with ceiling fans for breaking up stratification is that they add substantial wind-chill to the human occupants below, which is NOT what you're looking for during the heating season. A very small ducted solution for pulling hot air near the peak of the roof and directing it somewhere may be called for, but not the high cubic feet per minute of a ceiling fan blowing directly on the occupants.
In summer that wind-chill can be a good thing, but it also moves the hottest air down to where the humans (and air conditioning thermostat) are. It's better to run a horizontally directed fan a few feet from the floor making the humans more comfortable at a higher air temp rather than de-stratify the air in the room.
Roger,
I agree with Dana. For more information, see Using Ceiling Fans To Keep Cool Without AC.
thank you Dana and Martin, very valuable information. Article is great and just the type of "good science" I was looking for and unable to find elsewhere. Was going to sink $1,000 or so into a fan and installation, but now I'll save it for a proven energy saver.
A different view, I have an old Victorian with 12' ceilings in the living room. We installed a propane stove (sealed combustion using an old chimney for intake and exhaust) to supplement our forced hot water heat and have a back up in case the power went out. I thought it would throw a lot of heat, but it never seemed to get the room as warm as I thought it should.
Then one day when it had been on for a few hours I went to change a light bulb in a ceiling fixture. Once I got above the height of the doors it was like a sauna. There had to be at least a 20 temperature gradient. We all ready had a ceiling fan in the room for the summer, so I used a switch to reverse it.
Now we run the fan on low while the stove is on, there is no apparent wind since it is blowing up and the hot air now is pushed down the walls into the room. It seems to make the room much warmer and we have not noticed a draft or any noise. The fan is turning at about 10 rpm.
Hope this helps.
Stephen M
zone 6 maine
Superinsulate a home or have radiant floors for winter comfort....almost not strat...
I do like my ceiling fan for summer use.... I like the sound too.... puts me to sleep... have to have one in the Caribbean and Key West... at least I did.
As AJ suggests, the stratification problem is much worse when the envelope is poor. If the house is really well insulated and sealed, you can't sustain a very large temperature difference between the ceiling and floor. And even if there is a difference, the effect on overall heating cost is low.