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Old 06-30-2008, 04:29 PM   #1
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Attic fan in Attic access door


Hi
I have a fairly new 2 story home which is also a B&B. The upstairs rooms are not designed for any flow thru air. With rom doors shut, there is very little air movement. In addition there is a refigrator in the hall which adds to the heat load. I have full house ground coupled heat pump A/C but many times all I need is to move some air out of the upstairs into the attic. I am thinking about removing the attic access door (36 in wide std hgt) and replace with a wooden door with an attic fan mounted on the attic side. I am having trouble seeing how I would do the louvre vent on the house side of the door/fan. Ceiling units are designed to open against air flow and close with spring/gravity, but in this case the unit would be vertical, and I don't think it would work well without some serious redesign, which I could probably do. In winter, I would simply replace the "summer" door with the insulated "winter door"'.

Just wondering if anyone has done anything like this. No there is no other place to put the thing which is acceptable to my other half. The fan would pull from perhaps 3500 Sq ft, doors to rooms have clearance to floor.
Thanks

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Old 06-30-2008, 06:09 PM   #2
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Attic fan in Attic access door


I did play around with that a number of years ago, and I'm not sure I would go there again. There are many louvers to choose from that open and close with voltage applied. There are also a wide range of fans to choose from. But, what I liked the least was the sound that went with the fan. In my opinion no one makes a quiet fan.
If I were in your position though, I think I'd try installing a large turbine above the access in the roof and see if natural convection didn't take care of the problem. If it does, then you just need a "cover" for the opening.

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Old 07-01-2008, 07:56 AM   #3
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Attic fan in Attic access door


I was thinking of using a belt driven attic fan at low speed, I have them in my shop and when run slow they are pretty quiet, and move a lot of air. The turbine on the roof would surely result in my death or divorce! I will look for the louvers. Any more thoughts appreciated.
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Old 07-01-2008, 03:05 PM   #4
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Attic fan in Attic access door


I don't understand the "death or divorce". We must be on different pages. The turbines I speak of are quiet, Mother Nature operates them, and they are vastly superior to the common roof jacks. You might go to this link for some info: http://images.google.com/imgres?imgu...%3Den%26sa%3DN
Personally, I think your proposed change to your B&B is only adding to the basic problem that you have there. I would be very willing to bet that your attic is inadequately vented. You can easily check that by measuring the outside temperature and then using the same thermometer, measure the attic temperature. The readings should be about the same. If you have more than 5 or 10 degrees difference then you have a venting problem. There is plenty of good information concerning that on the Internet.
Secondly, if you have much difference between the first and second floor temperatures, then you have a circulation problem with your HVAC system. I would suspect that the lower vents are open too wide and the upper vents are either closed off too much, or by having the upstairs doors closed you have too little ventilation to the upstairs. If you think that is OK, then you might try turning the HVAC fan to always on.
If you still think that you want the attic fan, then somehow you are going to have to determine how much air you are wanting to remove. You will need that number to determine how large a fan you need to install and how large your louver needs to be. If you Google CFM Formula that will help you.
Good luck.
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Old 07-02-2008, 01:27 PM   #5
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Attic fan in Attic access door


Bob
Thanks for the info, I will check out the attic temp as you suggest. However, I believe there is plenty of vent in the attic, soffit vents front and back about 120 ft total plus roof ridge vents about 60 ft with house volume of about 28000 cuft. I know the hvac circulation is bad even though it cost me a small fortune when the house was built, heat works great but cold air doesn't get up stairs without axial flow helper fans which I installed in basement. Furnace fan is 2200 CFM with load sensing so it will always put out that amount of air until the electrical load is too high (Carrier 90%) and/or the fan just cavitates due to the load. All room register flow gates have been set every where with no real cure.
If I leave the AC on eventually the house temp is ok everywhere, however with a B&B you often have to turn the AC on and off depending upon guest preference (fresh air types) so just leaving it on all the time won't fly.
Roof vent would pull the attic if that is the problem, but it wouldn't affect the cross flow problem (over two ft of insulation on attic floor (bedroom ceiling) wife I am sure will not like the turbine up there hence the "death or divorce" comment.
Up stairs is open to downstairs, but there are doors on the individual bedrooms, and there are windows in those rooms but no way for cross ventilation with the bedroom doors shut, (and guests usually prefer them shut).
I am thinking that pulling some air out of the upstairs hall into the attic via the windows in the bedrooms (and the rest of the house) under the bedroom doors might provide some cross ventilation that currently does not exist in those two rooms. To control air volume I would belt the fan speed down till it feels about right, and I suppose that might require more venting in the bedroom doors too.
The other thing is that we only need AC once in a while, the outside temp is usually mild in the summer (Lake Michigan on one side, Grand Traverse bay on the other).
So given all this, do you have any more comments, I am all for doing this right but I can't fix the design problems already built into the walls and the house design.
Thanks for your thoughts/
Steve
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Old 07-02-2008, 09:18 PM   #6
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Steve,
I know about cavitations associated with marine propellers and air in pumps, but I'm not familiar with a circulating fan cavitating in air. How does that work?
It seems as though you are quite familiar with your dwelling. That is very good to hear. Most people that I talk to are not as knowledgeable as you. Kudu's to you.
I am also glad to hear that you have a ridge vent. If you have 120 ft of soffit vents and 60 ft of ridge vent (if the width is the standard 2 inches wide), you certainly don't need any roof turbines. And with the 2 feet of insulation, it seems doubtful to me that you have any problems in the attic.
It now seems reasonable to me that it is the closed bedroom doors that are the problem. In the old days that was solved with a transom above each door. I have seen a number of instances where a large register was installed in their place to allow air transfer from the room to the hallway. Now days there is usually a cold air return installed in each closed room.
You said that your furnace fan delivers 2200 CFM. That is 12 turns every hour. That's great. But since it isn't working for you, if you didn't like the options in the last paragraph, you should still be able to have the circulation fan running whether or not you have the heat or A/C running. Some HVAC units do not have this as a standard option, but there is always a way to make that happen. Sometimes there is a manual switch on the furnace unit. Some put the control on the thermostat. Sometimes you have to add a relay. And then there are some that want to add a smaller fan for that purpose. But there is always a way to circulate air 24/7 if you want.
It would be nice if you would tell me that the cold air return is upstairs at the end of a long hallway with the stairway at the opposite end of that hall, but I suppose that's out of the question?
I have purposely avoided the attic fan as I don't really find that situation workable. Once you penetrate the living quarters for your fan, you will be increasing the load on the HVAC by whatever the amount of air you pump out of the living quarters. Without going through an air to air heat exchanger, that could become too great a load for the A/C.
Bob
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Old 07-02-2008, 09:31 PM   #7
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Attic fan in Attic access door


I have been reading your thread and find it very interesting. The only thing that comes to mind is a question re. the fire codes in your area.

In a commercial setting attic fans or whole house exhaust fans are not allowed in some areas. Just thought I would ask if they are allowed in your area.

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Old 07-03-2008, 04:58 AM   #8
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Here a whole-house fan must be mounted in a hallway ceiling on the top floor of a house. An insulated, airtight seal is required to prevent air infiltration in winter. Fans should be sized to produce between 4-5 air changes per hour within the home and should have two speeds: low speed for continuous ventilation and high speed.
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Old 07-03-2008, 10:49 PM   #9
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Well thank you, are you quoting mechanical, building or fire code for commercial applications? I believe a B&b is considered a commercial application.

I dont claim to know, I was just curious.

This gentlmans first post seems like a good idea. Keep in mind that air, like water will follow the path of least resistance. With the room doors closed, it would be unlikely that air would be drawn from beneath the doors, instead of an open stairwell, but for occasional use, just to ventilate the upstairs, seems like a good idea.

If it was me however, I would not spend money only to find out later that it had to be removed, due to a code violation.

I would also be curious why a new build is unable to perform as designed. If the building was designed as a B&B, accomodatons should have been made for fresh air, based on total occupancy, let alone proper climate control. Lets keep in mind that newer commercial "E" requirements make it a no-no to open windows. Sounds like there is a base problem with your ductwork.

Didnt mean to get you guys side tracked.

If your fan meets code...try it!

Last edited by 8 Ball; 07-04-2008 at 12:10 AM.
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Old 09-17-2008, 01:50 PM   #10
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Attic fan in Attic access door


Quote:
Originally Posted by kubotaart View Post
Hi
I have a fairly new 2 story home which is also a B&B. The upstairs rooms are not designed for any flow thru air. With rom doors shut, there is very little air movement. In addition there is a refigrator in the hall which adds to the heat load. I have full house ground coupled heat pump A/C but many times all I need is to move some air out of the upstairs into the attic. I am thinking about removing the attic access door (36 in wide std hgt) and replace with a wooden door with an attic fan mounted on the attic side. I am having trouble seeing how I would do the louvre vent on the house side of the door/fan. Ceiling units are designed to open against air flow and close with spring/gravity, but in this case the unit would be vertical, and I don't think it would work well without some serious redesign, which I could probably do. In winter, I would simply replace the "summer" door with the insulated "winter door"'.

Just wondering if anyone has done anything like this. No there is no other place to put the thing which is acceptable to my other half. The fan would pull from perhaps 3500 Sq ft, doors to rooms have clearance to floor.
Thanks
Go to quietcoolfan.com scroll down click on video / im looking to cut my electric bill and in need of more air curculation and i found this to be my best bet having a NEW HOME also aprx 2 years old. havent got it in yet butwill let you know.

Last edited by Lenny W; 09-17-2008 at 02:01 PM.
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Old 09-17-2008, 01:55 PM   #11
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go to quietcoolfan.com , scroll down to video and watch. might help.. my other half is very pleased!!!!!!

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Last edited by Lenny W; 09-17-2008 at 03:02 PM.
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