I’ve been asked to install a whole house fan in an old home without central AC. The local big box has 2 sizes: a 30″ at 6,000 cfm and a 24″ at 4,500 cfm. The fan is going in the ceiling in the 2nd floor hall.
The house is only about 2,500 sq ft so I think the smaller fan should work just fine, but I don’t mind paying a little more if the bigger one is going to be quieter and/or work better.
Any thoughts?
-Don
Replies
I don't know about sizing.
But you want a 2 speed, belt drive unit.
Direct drive are too noisy.
Consider how you are going to seal this in the winter - they are massive heat leaks!
Actaully there are a couple of new ones out that have dual smaller vans and motorized insulated doors.Tamarack (sp?) has one. You can find them through http://www.efi.orgAnd there is another one that I am seening advertised in the lasted JLC.But they are several time the cost of the old kind.
I have the Tamarack and it certainly meets the insulated requirement. Not so sure about the air movement requirement though - it's kind of a matter of faith: the fans are running, they move x cfm of air so I must be getting a full air exchange every y minutes. In other words, you don't get the wind (or the loud noise) so it doesn't feel like it's doing much. I got mine just before they came out with the bigger fans - I'd definately go with the bigger unit or the "ghost", their new 2800 cfm unit. No one else has a solution to insulating that huge hole in your ceiling.
Consider how you are going to seal this in the winter - they are massive heat leaks!
Good point! I have one in my own home and it isn't really a problem, but my house is otherwise sealed up pretty good. In the old house I'm working on, I'm sure that there are many places where air can infiltrate.
It's probably still worth it to the HO, but it does incline me towards a smaller fan (thus, a smaller opening).
-Don
Check out this link at the Wall.
http://forums.invision.net/Thread.cfm?CFApp=2&Thread_ID=26958&mc=30
Whole house fans can cause some serious down drafting problems with heating equipment. Got to think of the house as a system.
Getting the too big one can have strange side effects. Mine is too big - I don't have enough vents around the roof to let the air out - so the attic becomes pressurised. When I run the fan, I smell the attic and have a breaze come through any unsealed holes.
FYI, I'm planning on adding a small cheap thermostat circuit with relay for controlling the fan automaticly. Then whenever the upstairs gets warmer than a certain point - it will start ventalating itself. Sealing up the gaps and adding more vent holes is also on the agenda!
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Those big fans are noisy, and way overpowered for the task. Plus, they are a pain to seal up for the winter (and unseal in the summer).
I have the Tamarack HV1000. It is a thing of beauty. Quiet, low power consumption, sealed doors. Easy install. No worries. I think the HV1000 is powerful enough for a house that size (mine is similar, and it works fine), but they do have a 1600 and the new "Ghost" model is 2800.
http://www.tamtech.com/products.htm
The fixer-upper house I bought in town had a 36" house fan and only 3 roof vents all of which werent cut into the sheathing but instead someone drilled about 20 holes in each.No wonder the dissappearing staircase wanted to jump open when the fan was on. Anybody need the makings of a hovercraft?
What I would like to see on these fan units is a smoke sensor that would shut off power to the fan incase of a house fire!
Seems like there should be a pretty simple way to connect into the smoke detector system, and shut off power to the fan at the circuit box. Just thinking at loud here.
The fans generally include a temperature sensor that will shut them down in case of a fire. (This is probably a UL requirement.) Not quite as quickly as a smoke detector would, however.
I wanted insulated doors, so I got the Tamarack HV1000. Moves 1000cfm. They also have a 1600 I believe, but my house isn't that big.
It's quieter than others, the doors are awesome, and it's very efficient. But it moves a lot less air. So it changes the temp of your house to match the outside air temp 4.5 - 6 times slower. That is to say, for 1500sf, in 12 minutes versus as little as two. As fast as the outside air temp changes (=slowly), that's neglible.
A friend has 3500sf and a giant fan. It's upside is you can actually feel a slight breeze across your skin when it runs. So the temp you perceive is actually less than reality. The HV1000 can't do that. Tamaracks also cost a little more in comparison. Check with your local utility for rebates.
Thanks for the real world experience. Like anything else, I guess it's a matter of trade-offs. I'll talk to the HO and find out their priorities. So far, all I know is that they want a "good" one.
-Don