HOME WISE : Vent Bathroom Fans Via Ductwork
QUESTION: My bathroom fan vents the air directly into the attic, not to the outside via ductwork.
The electrician who installed it said the vent fan motor wasn’t strong enough to push the air outside through the 15 feet of ductwork. He claimed the old fan motor burned out because the ductwork to vent the bathroom air was too long.
He then disconnected the old ductwork and vented the bathroom air directly into the attic. My large attic is well ventilated and insulated, but I’m still concerned. Is this OK?
ANSWER: You are justified in your concern about moisture and humidity in your attic space.
A well-ventilated attic will probably be able to eliminate the moisture and humidity vented from the bathroom during warm months.
However, problems may occur during winter months when the roof structural members are cool. Moisture from the bathroom air could condense in the attic and create structural problems. For this reason, your bathroom fan should exhaust air to the exterior.
In general, all ventilation equipment should carry air to the exterior of the house. Your situation is not uncommon.
Many residential bathroom fans are not designed to be ducted beyond a few feet from the fan. Adding ductwork and bends to the duct line could defeat the fan completely.
The solution is not to eliminate the duct. Instead, install a fan that can operate properly with the necessary duct attached to it. There are fans available that can do the job.
The effectiveness of the fan will depend on several factors:
--Ductwork length. Shorter runs are best.
--Ductwork size. Size it to the outlet on the fan. If possible, size ductwork one inch in diameter larger than the fan outlet.
--Ductwork surface. Smooth is best. Smooth ducts have less resistance than flexible ducts.
--Ductwork runs. Minimize the number of bends. Straight runs are best.
In your case, a long stretch of ductwork (15 feet) may be necessary to carry the air outdoors.
Since this is not ideal, be certain to minimize other factors that may reduce fan effectiveness. Size it properly to the ductwork, use a smooth-surface duct material and minimize bends or elbows.
Another consideration is noise. Adding duct to bath fans can increase the noise level of the fan. Noise level in this application is measured in sones . A lower sone rating is better. Keep the sone rating as close to two as possible.
A sone rating of one is about the same noise level as a quiet refrigerator. A properly sized fan, at an acceptable noise level, will ventilate your bathroom without creating moisture problems elsewhere.
Converting Electrical Outlets Not Easy Task
Q: I own a home built in the 1950s. All the electric outlets are two-prong types. I would like to update them with the three-prong outlets. Can I do this myself, or does it require an electrician?
A: “You can do the work yourself,” according to Roger Faris of Seattle’s Well Home Program, “but plan to be patient as upgrading electrical outlets can be difficult and time-consuming.”
It involves running ground wires or new cable, which includes a grounding wire, to each outlet you would like to convert. Outlets on the first floor require running wires under the floor in the basement or crawl space. If the basement is finished with a ceiling and walls, access to under-floor wires can be very difficult. Outlets on the second floor are generally accessed in the attic. This can be equally difficult if the attic is a finished space or if attic space is limited.
Paul Schuller of Green Lake Electric notes that outlet junction boxes, in some situations, are already grounded by the sheathing covering the electrical cable coming from the panel. Though less common, this makes the conversion much simpler and easier.
Schuller also advises getting an electrical permit from the city’s building department. Any work involving alteration of circuits requires such permits. Also, be prepared to check your work with an outlet ground checker to identify any improper wiring. They can be found at electrical supply stores and usually cost less than $10.
Before attempting to do the work yourself, make sure you know what you’re doing. Read up on the procedures, tools required, and safety precautions. If you have time, consider attending a workshop on electrical repair basics.
If upgrading the outlets is too much for the do-it-yourselfer in you, hire a licensed electricians. Start by getting bids from three professionals. Make sure the bids include an electrical permit and guaranteed conformance with the code, a full description of the work to be completed (including cleanup), a timetable, warranty, and payment schedule. Costs could range from $35 to $75 per outlet.
Once the conversion is made, you’ll find it much easier to make use of today’s modern appliances.
Three-prong outlets are particularly necessary for computer systems and appliances with motors and metal frames such as refrigerators, washing machines and dishwashers to prevent shocks.
Should Bedroom Be Insulated From Meter?
Q: My husband and I own a 5-year-old condo end unit. On our exterior bedroom wall is a utility base containing four electric meters. We are concerned since we sleep head on to the same wall. Could it be harmful having electrical equipment buzzing away so close? Please advise.
Also, do you recommend extra insulation in that wall to eliminate the hum. If so, what insulator should we use?
A: Frankly, the jury is out on this issue. We talked with Dr. Arthur Guy from the Center for Bio Engineering at the University of Washington to get some background.
There have been a number of studies on the effect of electromagnetic fields from electrical wiring in the last few years. A 1979 study in Denver showed higher than normal levels of leukemia in both children and adults exposed to certain types of wiring configurations. The problem is that subsequent studies show conflicting results. A follow-up study of children in Denver and of telephone line workers on the East Coast support the 1979 findings. Yet, studies of adults in Seattle and other places have not found higher incidence.
The type of wiring or appliance makes a difference. If the wire is tightly twisted or if there is a twin pair of wires serving the unit, the fields are canceled out.
If the current direction tends to be one way, there is greater chance of a field being established. According to a Bonneville Power Administration report, if there is any risk at all, it looks as if it is somewhat lower than that from secondary cigarette smoke, but higher than your exposure to asbestos in your home.
So we can’t definitively say you should move your bed, but you may want to for your own piece of mind. The strength of the field is reduced by the square of distance. That is, if you move the bed twice as far from it, the strength is only one fourth.
Lastly, we don’t think adding insulation to reduce the hum noise would help much as the vibration is probably coming through the studs. You could try mounting the meter panel on a vibration reducing pad to help lessen the noise.
Produced by the Washington Energy Extension Service, a division of the Washington State Energy Office. Reader questions cannot be answered individually. Questions of general interest will be addressed in this column.
