Should one pull air from outside into the house and the second one should push the air out? I am looking at having an attic exhaust fan installed, but I have a ridge vent on my house. The contractor said he typically closes 15 feet of the ridge vent around where he will place the attic fan. What are your thoughts on this? Also, should I have any concern over this fan being near the furnace in my attic?
Finally, he wants to install a cfm fan, but I may have a total of sq feet of attic space there is a soffit running the full length. I do have a dark roof. Are there any negative effects of having a fan that is too strong? Got that figured out.
Thanks, Lydiah. My house currently has several passive vents in the roof and I want to add a gable fan and have it draw air into the attic to help push the hot air out through the vents.
Is this a good idea? Also would I calculate the size of the fan using the same formula above? Im sure I need some sort of vent in my attic. I have a townhome and when i look from the outside I see only gable vents. It is VERY hot upstairs and cold downstairs and my power bill is so high. Do I need a vent and is this something I could install myself?
I really dont have an idea on how to size attic fan that is why I just asked someone to do it for me.
I have a 1, sq ft attic how many turtle vents wll I need,I also have 1 attic fan is this sufficient? I want to install gable mounted exhaust fan. What size is needed for the space being used? North gabled wall has decorative window. The south wall will be the location of the fan. It will be located over open stairs. Will the effect the flow? I understand the divide by to get the intake venting required, but is this the same if I am only using a power exhaust fan?
It seems that less would be needed since there would be a lower pressure side the attic and air would have more speed through the intake vent. Thank you!!!! Any suggestions? Soffit space is very limited.
No way have our vents met required air intake. I figure approx. Will appreciate any advice you can offer. Putting passive vents low on the roof to compensate for inadequate soffit venting is not a good idea.
The client had decided a new fan was needed to replace a solar unit they had installed several years ago. On inspection, I found the villain in the attic exactly as the customer described. A single, roof mounted, solar powered attic exhaust fan. It was working. There was no other ducting or HVAC equipment in the attic. The temperature of the roof sheathing inside the attic was degrees.
I explained to our client that the idea of attic fans to remove hot air from the attic area might seem logical. But they actually might need a bigger and better solution. Imagine yourself laying in the sun on a beach in Cancun. All is good for about 5 minutes then you start to feel hot. You go and get a big fan and set it up to blow air over you. Ah, feels better for about another 5 minutes. Soon even the blowing air feels hot, so you exchange the fan for an air conditioner and let that blow cold air on you.
Feels great now so you stay out in the sun till you notice that your skin is red and blistered and burned to a crisp. What happened? You got zapped by UV rays, a form of invisible radiant heat! Radiant heat zips right through cold air without any affect and cooks your skin. So, what does that have to do with your house? The roof structure of your Home An assembly of materials that enclose a weatherproof space for human living. Radiation from the sun heats the surface of the roof.
From there, the entire mass of the roof roofing, roof paper, nails, sheathing, rafters warms up through conduction. This radiant heat passes down through the attic space and hits the material on the surface of the ceiling structure insulation , wood joists, drywall , ducting etc.
Very quickly the entire mass of the ceiling structure also becomes a giant heat radiator. This heat moves back up towards the roof again and will continue to radiate heat well after the sun goes down. If your ceiling is not sealed airtight and extremely well-insulated, much of this heat is going to radiate downward into your home too.
Air in the attic that comes in contact with the surfaces of the hot framing, will become heated through conduction. This creates a kind of hot air sandwich formed between the roof and ceiling structures. The warming of all these surfaces is why the attic interior gets so much hotter than the exterior temperature. Help diagnose hard-to-find heat-loss areas, and pinpoint water leaks behind walls with new Thermal imaging cameras.
Read More…. As hot air is expelled through the vents on the high part of the roof, cool air is pulled through the soffit openings. Our highly trained technician will not only install the attic fan, they will also check out your vents to make sure they are functioning and clear of debris. Most homes require only 1 attic fan. However, homes with larger roofs may need 2 - 3 attic fans for them to work effectively.
Also, split-level homes often have separated roof areas, so to get the maximum benefit, we would install an attic fan for each separation. Our go-to attic fan for traditional homes are rated for up to 2, square feet and require at least square feet of fresh air intake so that a vacuum effect is not created. Over the years we have tried several other brands and have found the GAF Master Flow to hold up the best.
This type of fan can be purchased at your local Home Depot. Lowes Home Improvement carries Air Vent, which we have also found to be a good quality product. Air Vent offers limited lifetime warranties on their premium fans. Attic fans are usually installed on the roof. Roof-mounted attic fans are typically installed on the rear of the home and centered on the attic, which enables it to pull air evenly through the structure.
Another common location is on the gable vent. Gable attic fans are mounted on the gable vents themselves so that they can pull the air from one side of the attic and exhaust on the other side.
A master switch must be installed to shut off the attic fan for servicing or in an emergency. You can expect your attic fan to last between 10 - 15 years before needing its motor replaced.
The GAF Master Flow attic fans we install all come with a limited year manufacturer warranty so if your motor happens to go out on year 5, there would only be the cost of labor to replace. Did you know that reducing the temperature in the attic can actually extend the life of your roof?
The volume of the attic space can be easily calculated using length x breadth x height. If it is a sloped roof the calculations differ 0. The number of air changes depends on how hot your attic gets. But generally, it is 6 to 8 times per hour. As mentioned before it gives an approximate size for the attic fan. Practically no attic is 10 feet high. If you replace the height in the above formula with 7 ft you get Formula 1 in effect.
Depending on the number of air changes and the height of the attic the first formula makes sense. If your house has a steep roof then you will need a more powerful fan. The minimum attic fan size for a steep roof is CFM per sq. For example, if you have a sq. For an attic with a dark roof, the minimum size required for the attic fan is CFM for every sq. So if you have an attic of sq. So far the calculations are for determining the size of the attic fan. As you know an attic fan is an exhaust fan ie, it removes hot air from the attic.
This removed hot air needs to be replaced by cool air. This can be reduced to 1 sq.
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