Keeping thermostat fan `on' costs more than `auto'

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http://www.star-telegram.com/news/doc/1047/1:BPAGE63/1:BPAGE63070299.html

Updated: Friday, Jul. 2, 1999 at 09:09 CDT

Keeping thermostat fan `on' costs more than `auto'

By Cummings

c.1999 News Service

DAYTON, Ohio -- Last week I talked a bit about energy-efficient use of air

conditioning, and we'll get back into some summer energy issues next week.

In the meantime, I have an answer to three reader questions, including one

question about summer energy.

Fan the air

M.G. of Washington Twp. has central air conditioning, and on her thermostats

she can set the fan on either " on " or " auto. " She wanted to know which

setting was most energy efficient.

Solution: Forced-air heating and cooling systems have fans that blow to

circulate air around your house. In the summer, the fan blows cool air into

rooms and helps draw unheated air out. When the thermostat switch is in the

auto position, the fan comes on only when the system is active and producing

cool air. When the switch is in the on position, the fan blows continuously.

Walt Hibner, program manager for Dayton Power and Light Co.'s Energy

Resource Center, said running the fan continuously uses energy, but it may

also help you feel more comfortable. He said when the fan is off, cool air

settles near the floor in your house and warm air rises toward the ceiling.

Turning on the fan mixes the air in your rooms, and lifting the cool air

from near the floor may make you feel cooler.

However, he said, it costs about $98 to run a fan continuously through the

cooling season. You'll spend only about $31 for fan energy if the system is

left on auto.

M.G. pointed out correctly that the most important consideration is the

temperature setting on the thermostat. If you can live with a slightly

higher temperature setting with the fan running, it's probably a good

trade-off.

Another option is using ceiling fans. A ceiling fan set to pull air up from

the floor does the same air mixing job an air-conditioning system fan does.

And Hibner said a ceiling fan may cost only $4 or $5 a year to operate.

Railroad ties

R.M. of Dayton has a small vegetable garden surrounded by railroad ties. He

wondered if the creosote that is used in the ties could find its way into

food grown in the garden and threaten his family's health.

Solution: Finding a definitive answer to this one proved difficult.

Creosote, an oily substance produced by distilling wood tar, once was used

for treating bronchial ailments and, later, as a treatment to protect wood

from insect attack. It is a toxin that is no longer available to the general

public, but it was widely used to preserve railroad ties and telephone

poles.

I contacted several sources who had conflicting opinions, but Pete Lane, an

agent for the Ohio State University Extension Service in Dayton, had what

seemed to be the most reasonable answer. He said creosote is water soluble

and washes out of the wood over time as it is exposed to the elements. Most

of the railroad ties being sold for landscaping have been outdoors long

enough that a lot of the creosote is gone.

Lane said if enough creosote is left in the railroad ties to be harmful, the

most likely effect will be that it kills the vegetable plants. The chance

that significant creosote will be taken into the plants and reach the people

eating the vegetables seems slim.

Pressure-treated lumber is probably a better choice for a vegetable-garden

border than railroad ties. Treated lumber also has toxins, but they are less

likely to leach out into the soil.

Of course, you should never use treated lumber on a surface where it touches

food you are preparing.