Ventilation
Virtually every house has some venting in or near the roof, although most really don’t have as much as they should. The purpose of roof-area vents is to pre vent moisture from being trapped at the top of the house, where it can rot the plaster, insulation, and wood; and blister the paint.
In general, a properly insulated attic will have about 1 square foot of ventilation for every 300 square feet of ceiling area. Because the insulation’s vapor barrier keeps household moisture out of the attic, the less insulation you have, the more venting you need, since proper ventilation helps keep moisture from condensing. In any case, it’s almost impossible to have too much venting in your attic or crawlspace.
There are many kinds of vents, distinguished mostly by their positions in the attic or crawlspace. The most common venting arrangement consists of a full length of soffit vents and two gable vents (rectangular or triangular), one at either end of the roof’s peak. Vents at the roof’s ridge are also common.
Most vents simply permit air to flow through themselves and the attic, with out providing anything more than their presence to encourage this air flow. The turbine vent is an exception—the lightest breeze makes its blades begin to spin, producing a slight low pressure inside the attic and actually drawing air through the space. Motorized ventilators are also available.
Roof vents are easy to install; you need only measure and cut out a piece of roof or wall that’s the same size as the vent, and then insert the vent in the cut-out portion. A system of 2 by 4 inch headers should frame any hole you cut. Then, when you’ve placed the vent according to the manufacturer’s instructions, caulk and flash the area around it to keep the roof from leaking (see “Caulking”).
Installing a Turbine (or Other Roof Top Ventilation)
1. Measure and cut a hole, the size of the vent base, through the shingles, roofing felt and sheathing. Be sure the hole is centered between rafters.
2. Apply roofing cement or caulking to the underside of the vent base flange and slide it under the surrounding shingles so the base is centered over the hole.
3. Nail the flange in place. Replace shingles if necessary and caulk the edge of the flange and nail heads.
4. Set the turbine (or other vent top) on the base. Level and secure it as shown on its instruction sheet.
How Vents Work: Triangular gable vent; Ridge vent with undereaves
vents.
Installing a Triangular Gable Vent: 1. Cut the hole the size indicated on the
manufacturer’s instruction sheet. Be sure to allow for the 2 x 4 header. 2.
Nail in the header. 3. Install the vent according to the instructions. 4.
Caulk the edges outside.
Fans
We must admit that simply opening your doors and windows to get circulating air does pose a problem: The air flow these openings provide may be sporadic and gusty—or nonexistent on particularly hot days. This unsystematic method leaves your comfort up to the winds of chance. Fans, on the other hand, provide a more determined cooling effect by propelling, sucking, or forcing air through the living space.
All fans have the same general purpose, and all function in the same general way. So feel free to choose from among large or small; portable or in stalled; oscillating, tilting, or stable; and window or table fans.
• Whole-house attic fan: The whole- house attic fan is usually an excellent investment. It can increase the comfort level throughout your house, satisfy all your cooling needs on many days, and give your central air conditioner a good, energy-conserving boost.
Whole-house attic fans range in price from about $100 to $400 (not including installation and any of a variety of accessories you might want, such as shutters). If you can get another person to help you, you can install this fan fairly easily.
Whole-house attic fans require that the house and attic be open to each other. Otherwise the living area will not receive the ventilating benefits the fan provides. However, you don’t want your fan to stir up loose fill insulation or fiber glass dust from your attic; so if you’re thinking about installing a whole-house attic fan, first discuss this point with a conservation analyst from your local utility company.
• Installing a whole-house attic fan: There are three main ways to install a whole-house attic fan, illustrated below. To make use of any of these methods, you must have two air passages—one from the living space to the fan, and another from the fan to the outside. You may be able to use an existing opening, such as a stairway or door, or you may have to cut both openings. If major wiring is required, don’t do it yourself—hire an electrician.
When installing the fan, always follow the manufacturer’s instructions. The step-by-step instructions that follow are only a general guide.
Once in operation, the fan will draw air from all parts of the house. Be sure that at least some windows or doors are open before you turn on the fan, or your pilot lights may go out, and soot may be drawn from your chimney. If you want the fan to circulate air strongly in one area, close off the remaining rooms.
A note on safety: If children or pets are at all likely to come near this fan, install some sort of barrier around it. The blades can do severe and permanent damage to the person or animal who stumbles into them, and there’s no reason to turn your comfort into a disaster.
How the Whole-house Attic Fan Circulates Air
The Whole-house Attic Fan and Three Installation
Positions: Ceiling-mount
fan with directional housing; Wall-mount fan in gable; Ceiling-mount fan
in ceiling.
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How to Install a Whole-house Attic Fan:
1. Cut a frame for the fan by sawing through the floor joists and adding headers on both cut sides. The inside dimensions of the frame should
equal the size of the shutter that will cover the vent opening from below.
2. Build a platform of 1 by 6s to fit over the headers and intact
joists.
3. Carefully set the
fan into its frame. 5. Screw in the ceiling shutter from below. 6. Have
the major wiring any wiring you don’t feel absolutely certain about—connected
by a professional. 4. Toenail through the frame to secure the fan.
• Attic fans: Don’t confuse a whole- house attic fan with a plain attic fan— their purposes are quite different. During hot weather, an attic can become extremely warm, especially if it is well- insulated and holds in heat. The built-up heat may leak down into your living space, reducing your comfort; if you run your air conditioner to combat the extra warmth, you end up increasing your utility bill.
The main value of attic fans is in re leasing pent-up heat, and this end can usually be better accomplished with adequate venting. But you can use an attic fan to create additional circulation in your attic (the attic is still closed off from the living area). The fan propels the heated air out through a system of attic vents.
Installing an Attic Fan:
Air Conditioners
Central air conditioning works by passing air through a chilling system roughly similar to that of a refrigerator. It works simply and directly, but expensively. Room air conditioning is not as expensive, but it still adds significantly to your utility bill. Despite the rising costs of the fuel needed to operate them, these methods remain popular because of their simplicity, directness, and effectiveness. If you already own either one of these cooling systems, take good care of it and it will give you better ser vice for a longer period of time at lower cost.
• Air conditioner maintenance: To find out how to maintain your air conditioner on your own, talk to your dealer or service person. In general, you should clean a central air conditioner’s con denser coils annually, and clean or re place its air filters every month or two, depending on the frequency and intensity with which you use the unit. You can clean the coils with an ordinary vacuum cleaner, sucking up the dust that has accumulated. If the hose on your cleaner will not fit between the coils, you can also reverse the vacuum and blow the dirt away. and you can reduce the air conditioner’s fuel waste by providing some shade or cover for the condenser outside (of course, make sure that the shading doesn’t block the passage of air into or around the condenser).
Like your furnace, your air conditioner should receive an annual checkup from a trained service person. The best time of year for the checkup is spring, just before the air conditioner will be in frequent use. Have the service person oil all unsealed bearings; tighten belts; check for and repair refrigerant fluid leaks, and add refrigerant if necessary; flush the evaporator drain line; and se cure all electrical connections. In addition, if your heating and cooling systems use the same ducts, the dampers should be adjusted each time you change from one system to the other, since each one requires a different setting.
• Use your air conditioner wisely: Learning to use your air conditioner effectively can help reduce your energy bills a great deal. For starters, keep your windows closed while the air conditioner is on; close your drapes to keep the sun out of any room you want to cool; and don’t run your air conditioner when you’re going to be gone for any length of time. But to make your air conditioner truly effective, remember that its principal purpose is to condition the air, not just to cool it. Use it only when you must.
Cleaning Air Conditioners Condenser Coils
Next: Water Heaters