Whole House Fan Installation
How Should a Whole House Fan Be Used?If you want quiet, energy-efficient cooling in the spring, summer, and fall, a whole-house fan makes a wonderful addition to your home. These units give a natural cooling effect by drawing fresh air from the outside and cycling it through the home. Eventually the air will be sent out through vents in the attic.
In dry climates, or at least when humidity is low, whole-house fan use is simple. Essentially, they can eliminate the need for running the air conditioner as long as the exterior air is not too hot. What you might not realize, however, is that whole house systems can be effective for almost any area in the United States. While different locations will be able to use them in different seasons, whole house fans can find use in practically any setting.
To properly operate your fan, start by opening the windows in your home. This will ensure you do not have unsafe negative pressure, which can draw gasses inward. Also, close any fireplaces or other sources of gas to avoid pulling chemicals into the living space.
You will also need to open the vents in the attic. Having open vents will provide an outward flow of air, completing the cycle of natural ventilation.
Now turn on the fan and let the machine do its work. In many cases, it may be best to run it throughout the evening, then once the morning sun rises, you can turn off the fan and close the house. If you have decent insulation, your home should hold the cool air throughout the day, which means you won’t have to run the energy-eating air conditioner.
Installing the Oransi Fan: The Basic StepsStart by finding a spot where the fan will be placed. The best location is in the ceiling of a hallway, which allows air from all locations of the home to circulate. If you place it in a room the circulation will be limited when the doors are shut.
Tools You Will Need:
- Drywall saw
- Phillips screwdriver
- Power drill
NOTE: Local building codes and standards must be adhered to in the installation of this unit.
AVOID BACK DRAFTS: Care should be taken to avoid back drafting combustion appliances that are installed in the conditioned space. Whole house fans are capable of pulling large quantities of air, from the home, particularly if not enough windows are open. This could easily back draft gas appliances located inside your home. Take care if you have gas appliances installed inside of your home.
Determine from inside your home where to install the fan. If you have one system it is generally best to locate in a central location on the top floor ceiling. If you are installing multiple units, such as in bedrooms, be sure to consider the access and clearance in the attic space above.
In the attic, mark the location for the fan. Make sure you have a minimum of 30” of clearance. Take the cardboard cut-out template and a small screwdriver with you. Make sure the template fits between the beams with 2” of clearance on both sides.
When you have chosen your location, place the provided template on the spot and mark it at each corner by pushing the screwdriver through each corner to make a hole. This will allow you to see the corners from the living area below.
From below, place the cut-out template on the ceiling, making sure that you have at least 2 inches of clearance all around it. While holding the template in place, mark its outline with a pencil.
Using a drywall saw or similar device, cut out the hole in the ceiling.
Take the main assembly, which includes the fan/motor housing and damper box into the attic through the crawl hole and move into position near the ceiling cut-out hole. If needed, you can disassemble the fan from the damper box.
Place the damper box through the hole in the ceiling.
Using standard drywall screws (not included - mounting holes are 0.228” diameter), fasten the damper box to the drywall and the joist in the attic.
Fasten the damper box to the ceiling joists AND drywall. The purpose of this is to make sure the damper box stays in place when you are screwing in the grille. If you do not fasten the damper box to the drywall, the damper box will not stay in place when attempting to screw in the grille
Center the grille over the damper box. Install the grille by screwing through the drywall into the flange of the damper box.
Some ceiling surfaces are uneven and may cause a small gap to be present. This can easily be caulked later if excessive.
WiringWiring diagrams are for examples only and wiring should be done by an experienced electrician. 12 or 14-gauge romex is common. Check your local building code before choosing the wire type.
Once you have your location selected, cut two pieces of a 2x10 to the width of the distance between the floor joists. Essentially what you will have is a box built into the floor; two sides will be the new 2x10 pieces, while the other two sides will be the floor joists themselves. Square the boards and nail the 2x10s into place and you have the required box.
Now you need to cut holes in the plywood that creates the floor of the attic, as well as the drywall that creates the hallway ceiling. To cut the plywood (assuming the attic floor is covered with plywood; not all are), you will use a plunge router with a bearing on the bit that will keep you from cutting the joists and 2x10. Measure to the center of the box from the edge, and drill a hole to start the router. Now you can work the router to the edge of the box, where the bearing will force the router to stop; you can then guide the router around the edges of the box to cut a perfect hole in the plywood.
From the attic, use a reciprocating saw and cut the drywall to finish the hole. With this tool, you can easily cut the hole you need, but before doing so, take time to move any wiring or other obstacles, If there are wires that run through your hole, you can simply staple them out of the way against one of the box walls. Now you have a clear path to cut your hole.
There could be a gap between the remaining drywall and the joists; if so use a foam insulation to seal the gap. Having a gap will reduce the effectiveness of the whole-house fan, so don’t leave this unplugged.
Proper Ventilation is KeyOne of the most important aspects is proper ventilation. You need to be able to move air through the entire home, but it also needs a place to expel air so new air can come in.
The vents in your attic need to be sized properly so your whole-house fan works correctly. There is a specific procedure that includes measuring the home and finding the right whole-house fan speed and power. Once you determine the fan power, you can determine exactly how much square footage you need for your ventilation.
The Role of an Attic Fan?It’s important to understand that a whole-house fan is not the same thing as an attic fan or powered attic ventilator.
While a whole-house fan moves air throughout the entire home, bringing in fresh air and creating a cool sensation through the living space, an attic fan only moves air inside the attic. Attic fans move air from inside the attic and vent it outward. Some units are programmed with a thermostat-controlled ventilator, which opens when the attic reaches a certain temperature. The goal of an attic fan is to reduce the overall temperature in the attic, which should help control the temperature in the main living space.