I want to install a few attic and whole house fans at my parent's apartment complex since the humidity is fairly high, and there is no type of ventilation, at all, in the entire building.
I was looking through the NEC for a little bit, but couldn't find nothing on it.
It's definitely going to be on a dedicated branch circuit.
What I wanted to know is if NM cable is permissible to be used from the panel, to the junction box. MC cable is probably used from the fan's electrical box to the junction box.
Secondly, I would like to have someone's opinion on how it should be wired in terms of switching it. I'm not going to be there, 24/7, but I don't know if the tenants are going to want to turn the switch on every time they cook or shower, might be too much for them to do or even remember. How would I go about doing this?
[This message has been edited by DSpanoudakis (edited 09-01-2005).]
Good evening: First, based on your profile info, I have no idea of your qualifications, or backround. Whole house fans can have motors that range from 1/2 to 5 HP. "Attic fans' usually are under 9 amps each, and yes a dedicated circuit may be required. Control can be a t'stat, timeclock, humidistat, switch, or any combo.
Depending where you are, working in a multi family may require a lic. electrical contractor; and a permit probably is also required.
More info on what you intend to do would be helpful
#95161 - 09/01/0506:26 PMRe: Attic/Whole house fans. Anything in the NEC?
Ok, well there is 4 apartment buildings, consisting of 3-4 apartments each. All, are single floor buildings. All, have the same type of truss framing from one side of the building, to the other. All, have no type of ventilation, at all. All they have is a louvered vent on one side, and one on the other. But, there is no ventilation under the eves, nor any vents. The attic spans from one side of the building, to the other, without any walls or breaks.
I've been having A LOT of compplaints about dampness in the sheetrock, especially around the bathroom area. Come to find out, previous owner had installed 1/2" sheetrock for general purpose walls, none for damp locations (the green colored rock). Well, I changed out a few of them. Still, there's some damp spots, soft spots, and the entire attic is just plaing damp, humid, and extremely hot.
The bathroom fan vents do work, but none are ducted to the exterior of the building. For one thing, the insulation surrounds these fans, instead of having some 6" all around of the fan box, of free space. So, I do believe this is a fire hazard, and am going to change this soon. So, all the vents throw air straight into the attic. So, I'm planning on ducting all the bathroom vents and range hood vent straight out of the building.
The range hoods are also vented straight into the attic, with no duct work to throw any of the air to the outside.
I recently replaced a bathroom vent fan when the tenant was cooking. The vent fan was approx. 5 ft. from the range hood vent. Jesus christ, the amount of damp, humid, hot air that came after she was cooking was unbelieveable, and I think this is the reason why most of the walls, around the bathooms, are this way.
I was planning on installing a whole house fan in each apartment. So, 3 or 4 per building. Plus, installing an attic fan, roof-mounted type, 1 on each end of each building.
These are 23 year-old buildings with hardly any insulation left over. They used the black-type, black cotton-looking type of insulation (name escapes me right now). There is probably no more than 3-4" of it left.
Anyone's input greatly appreciated.
[This message has been edited by DSpanoudakis (edited 09-01-2005).]
#95162 - 09/01/0509:56 PMRe: Attic/Whole house fans. Anything in the NEC?
OK, the insulation sounds like a type of "rock-wool".
Exhaust fans from resi bathrooms have been required to be vented outside around here as long as I can remember; and kitchen range hoods also.
Gut feeling is all exhaust fans should be properly vented to the exterior, with APPROVED ducting and caps.
Again, I think that what you are calling a 'whole house fan', and what I call a 'whole house fan' are two different animals. The attic ventilator fans, if properly sized will provide proper ventilation for the attic, IF adequate make-up air (intake) is available.
#95163 - 09/02/0512:09 AMRe: Attic/Whole house fans. Anything in the NEC?
Indeed, I was surprised that none of the vents were ducted. Of course, I will use proper ducting and caps on the outside, made for venting.
The whole house fans I was talking about are the ones that mount to the ceiling joists, and you can see the screen or louvers on your ceiling. The attic fans I'm talking about are the ones that mount to a vertical wall in your attic or the ones that mount to the roof, if no vertical walls are present or you have no space on them.
What do you mean by this sentence: "adequate make-up air (intake) is available."?
#95164 - 09/02/0502:09 AMRe: Attic/Whole house fans. Anything in the NEC?
"Makeup air" is the air required to provide adequate ventilation based on the CFM of the fan.
Imagine that you have a 16" box fan in a window (fan completely sealed and no screen on the window) in a small 8'x8' room and the door is closed. You would notice that not much air is being pulled through the room and exhausted out the window. That is because there is very little "makeup air" coming in from what little space there is around the door that allows air through. Now, open the door and you would see that there would be plenty of airflow through the room.
NuTone (a fan manufacturer) recomends 1 square foot of open ventilation for every 300 CFM.
You need to see if there is any soffit (sp?) vents, gable vents, ridge vents, etc. and then determine what the sum of their square footage is.
The best "makeup air" venting would be soffit vents.
If you do have a gable vent and are gong to install a powered fan in it, make sure that you close the space around the fan or you will just be drawing air from it and not the soffit vents.
Hope this helps.
#95165 - 09/02/0511:16 AMRe: Attic/Whole house fans. Anything in the NEC?
That's what I thought it meant. But, that's the reason why I wanted to install a whole house fan, so air can be drawn into the attic, then out by the attic fan.
I have no eave or soffit ventilation, no louvered screens, NOTHING. The only ventilation there is are 2 3'x3' louvered vents on each side of the building, but each building spans about 50-60 ft.
For the most part, all of the tenants have their windows open, so there will be a good amount of air being drawn in. This is the reason why I wanted to use whole house fans in each apartment, so, all hot/humid air would be drawn into the attic, with the help of the outside incoming air. Therefore, the attic fan will draw out of that air out of the attic.
#95166 - 09/02/0508:13 PMRe: Attic/Whole house fans. Anything in the NEC?
Do not install any fans until all venting is properly installed. This may take care of the problem and save a lot of money on whole house fan. Grainger catalog use to have a formula that needed to know the cubic feet of house the cubic feet of attic space the vent openings sizes and window and door openings then it would give the size of whole house fan and tell how much more ventilation needed. So seeing all this work and cost just try to vent everything outside and give it a try.
#95168 - 09/02/0511:57 PMRe: Attic/Whole house fans. Anything in the NEC?
I "think" (warning! warning! warning!)(grin) I recall a "basic" formula of 1 sqft of vent opening per 150-200 sqft of attick floor space.
You are certainly correct that the first thing DSpanoudakis needs to do is to ensure that he has proper vent opening into the attic. It sounds like he seriously needs to get som soffit venting installed, as the two gable vents just won't cut it.