12-month furnace filters might not go the distance

Q Are so-called 12-month furnace filters worth the cost? Do they really last that long, or is it more efficient and better to change the filter more frequently, using less-expensive filters?

A If the touted 12-month filter fits into a standard 1-inch slot, it might not work effectively over time, said Bruce Boerner, an energy efficiency engineer at Xcel Energy.

"It will most likely get too dirty and the airflow will be reduced significantly over the 12 months," he said.

To be viable for 12 months, a filter would need to be 3 to 4 inches deep, he said.

"With the higher surface area, the filter would still be able to effectively remove the dirt and not have excessive reductions in airflow when the filter gets as dirty as it should when the filter is left in place for 12 months," Boemer said.

Using such a filter also would require duct modifications, he added.

Xcel also endorses following manufacturers' recommendations for a furnace, which generally call for checking the filter every month and changing it every three months.

Donating eyeglasses Q I have older prescription eyeglasses. Where can I donate them?

A LensCrafters and Pearle Vision stores have eyeglass collection programs and distribute eyeglasses to underprivileged people worldwide. Bring prescription eyeglasses and nonprescription sunglasses to the store's drop-off boxes.

LYNN UNDERWOOD

Drilling a marble top Q I have a built-in desk in my kitchen with a Carrera marble top. I need to drill a small hole in the marble to accommodate power cords, because the only electrical outlet is on the wall under the desk. Any suggestions on who is best to take this on?

A Drilling marble can be a messy and tedious job and it requires specialized equipment -- such as a diamond drill bit -- and the knowledge to do the job right.

Also consider the long-term effect of drilling through the marble top and the future use of the area. You might not always have a need for power cords in that space, but the hole will be there forever. One option might be to have an electrician install an outlet above the desk that ties into the outlet below.

ANGIE HICKS, ANGIE'S LIST