bath exhaust fans instead of ceiling fan in cathedral?
Hi there!
I really don’t like ceiling fans and have been searching for an alternative solution in my new construction project.
I have a 32x20ft room with a shed cathedral going from 8ft up to 14ft. It’s a blown closed-cell insulation hot roof above.
The heat and air is a mini-split system with two head equally placed about 8ft high on the tall wall.
zone is Coastal NC.
I’m considering top of the tall wall mounted bath super silent exhaust fans at each end of the room that would have ducts that ran down inside the wall, exiting inside the room at the low point of the wall near the floor. Idea is in winter to pump that trapped hot air in the cathedral down to the floor for distribution.
I figured something like this would exist but google did not really turn anything up.
Wondering if my idea makes sense…
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Replies
Possibly, but my preference would be to upgrade the R-value of the ceiling to at least R-50, do a meticulous job of air sealing that and everywhere else, insulate the walls to at least R-30, and use high performance windows. Then, if the top of the room gets hot, very little of it will escape, and it won't cost you much to just let it be. R-50 will be expensive with spray foam so you might check out the other options in this article:
https://www.greenbuildingadvisor.com/article/five-cathedral-ceilings-that-work
Bryan,
If you are building an energy efficient and relatively tight home, you don't need ceiling fans for comfort. I didn't install any in my last home, and it was fine (CZ3A). When I updated the townhouse we moved into a couple of years ago, I removed all the old, junky ceiling fans. It is fine without them.
You do need to think about a ventilation strategy for your home. Something like the Panasonic IntelliBalance might be worth considering. There is lots of info on GBA about that topic.
Some of the mini-split brochures have the fan/duct setup you're talking about, but with ducted mini-split heads in the wall and usually the opposite duct direction (low intake, high-wall exit). Really makes a beautiful install with linear bar grills, etc., but not as efficient as a ductless head.
We have a virtually identical sized/shaped room in the Charlotte area (33x19, with 8/14 ceiling). When asking general questions about ductless heads a long time ago, I was told that high mounted ductless heads would likely provide enough throw and movement/swirl to prevent normal stratification, as the blower runs continuously regardless of thermal output. If your units are on the tall wall, there may be some pros/cons to changing the height to higher on the wall as well, but I don't know if there is a practical height limit for a given room geometry (that's a question for the experts).
Based on the answers I got, I'm not convinced that you need to add the functionality of a ceiling fan, as the ductless heads may do that job just fine.... That's the first question that you may want to explore though.
Great info all, I just met with my HVAC contractor today and he said basically the same thing. I was already going to have R50 in the ceiling, R38 in the floor, and R19 in the walls with a 1.5inch rainscreen gap that also has a thermal benefit. So guess I’ll ditch the fan for sure. I’m taking great pains to make the house as airtight as possible, so the HVAC guy also mentioned the Panasonic system to bring in some fresh air.
Sounds like you have a rare find, an excellent HVAC contractor!