why not a ceiling fan

20 years ago

All the greenhouse supplier's sell exhaust fans that are small blade high speed fans that would sound like an airplane ready for takeoff.

These fans cost around $ 200.00

Since my new greenhouse will have four roof vents and I plan on installing automatic openers on all the vents I think I will use a ceiling fan.

I plan on installing motorized shutters down both sides I can hook up the shutters and the fan to a thermostat and set it 2 degrees higher than the roof vent opening temp

When the roof vents open the shutters would open and the fan would start automatically.

The fan would draw cool air in the shutters and blow it out the roof vent if it was run in reverse,

This fan will run quiet and cost less and it has a lifetime warranty.

I have a very good commercial voltage regulator that I could use to make the fan turn really slow.

With the ability to run it real slow I could use it at night when the greenhouse was closed and the heat was on. No need for extra circulation fans one fan could do it all

The 10X12 HFH has a 10 foot ceiling and 8 foot side walls so if I use a 18 inch drop rod on the fan it will clear the roof and still have over 8 feet of head room below the blades.

Anyone see a problem with this idea. I think it would cost less run much quieter and cool better than the conventional method of cooling and circulating air in my greenhouse.

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Comments (9)

nathanhurst
20 years ago
Certainly fans become more efficient and quieter as they get bigger. I'm just not sure I understand how the air is going to get out. A ceiling fan won't give you much pressure differential though - you would have to use separately actuated vents rather than relying on the fan to open them.

Ceiling fans would be a good alternative to HAF in small greenhouses.
gardenerwantabe
Original Author
20 years ago
NATHANHURST
I plan on putting the four roof vents together in the center instead of spacing them out. The ceiling fan will be directly under the roof vents and when run in reverse the air movement is upward. If you have ever been under one of these fans when it was on high you know they move a very large volume of air. The cool air would be drawn in the vents at the bottom sides and pulled up and out the roof vents. This flow eliminates the hot air buildup near the roof and vents it out the top.
After dark when heating you can run it really slow and force hot air down away from the ceiling just the reverse of daytime operation
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cactusfreak
20 years ago
I use a ceiling fan 24/7 in my greenhouse. But it is just for circulating the air. So I don't have to use my large HAF's. It does cool somewhat and blow the heat back down from the ceiling.
I still have to use exhaust fans and shutters for air exchange. I don't think a single ceiling fan has enough cfm's to pull in enough outside air for a complete air exchange every 1-2 minutes. I only do air exchanges when the inside temperature goes over 80 degrees and I only use one exhaust fan in the winter to keep from blasting my plants with cold air. So if you intend to use the ceiling fan for cooling in the summer I don't think it will be enough without exhaust fans. But for general air circulation esp. in the winter, ceiling fans are perfect.
nathanhurst
20 years ago
A ceiling fan will have an excellent cfm (volume), the problem is their low static pressure limit.
gardenerwantabe
Original Author
20 years ago
Lowe's has them on sale I think I will buy one and then we will know if it works or not.
Recently I installed a new furnace and I kept the blower out of the old one. It is a axial flow what some call a squirrel cage blower and it will really move a lot of air.
If the ceiling fan don't work I can use the furnace blower but it would have to be used as a exhaust not blowing into the greenhouse the outlet is only about 16 inch square and the air coming out is like a hurricane. I can slow it down that may be necessary.
nathanhurst
20 years ago
A fan will move more air than a blower. A blower will produce more static pressure. The smaller the hole which air moves, the more energy required to move a given volume/mass of air.

The biggest problem I can see for a ceiling fan is the condensing humidity will probably corrode the insides fairly quickly.
trigger_m
20 years ago
i use a ceiling fan in my greenhouse.it came from lowes-and is made for indoor/outdoor operation.have used it for 2 years-works perfect.it's mainly for circulation of the heat from heater at night.still use exhaust fan,with thermostat.
milwdave
20 years ago
On the HFGH I'm not sure how you would mount it. There's not a lot of heavy duty solid surface there. But I haven't seen the 10 x 12 yet...so who knows? Can't hurt to experiment.

Dave
Milwaukee
wolflover
20 years ago
I've used two ceiling fans in my greenhouse 24/7 for the past year and a half. Mine are cheapo ceiling fans with light kits from Lowes. I paid less than $25 each for them and they've been great and look good too. :) Mine are mainly used to circulate heat and air, but I use an exhaust fan and shutter on a thermostat for my air exchange. I really like the light kits on the ceiling fans. They are handy when I want to go play in the greenhouse after dark.