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Your Utility Bills: Choosing room air cleaners

Dear Jim: I have a central air cleaner on the furnace, but my allergist recommended room air cleaners too. How can I tell which ones are most effective and is there much difference in electricity use? – Sandi H.

Dear Sandi: Although all the marketing hype on the packaging indicates they all are the best, there are significant differences among various room air cleaners. Don’t just base your decision upon the external physical size or the price. Getting one with the proper filtration method is most important.

Using room air cleaners does not eliminate the need for the main furnace filter. It removes particles that stay suspended in the air through the ductwork. This not only helps indoor air quality, but it keeps the heat exchanger clean for better furnace efficiency. The amount of electricity used by room air cleaners does not vary much among the designs.

Many of the particles and allergens in room air are relatively large (mold, pollen) so they do not stay suspended long enough to make it all the way to the furnace filter. They puff up each time someone sits on a sofa or bed, so room air cleaners are more effective for removing these.

The Association of Home Appliance Manufacturers has testing standards to rate the effectiveness of different types of room air cleaners. It is called clean air delivery rates (CADR). This allows you to compare the effectiveness without having to consider the design or the type of filter material.

First check with your allergist to determine which allergens are causing the most problems for your health. The particle size varies significantly for various allergens, so it is important to know which ones need to be removed from the room air.

The CADR rating tests are done for the three most common particles in the air – household dust, tobacco smoke and pollen. Most allergens are in this range of particle sizes. Each air cleaner will have three individual rating numbers, one for each particle of the above sizes. A filter which is good for pollen may not be very effective for smoke.

To use the CADR rating when selecting a model, calculate the square footage of the room and multiply it by 0.67. For example, if you need to remove pollen from a 10-by-12-foot bedroom, the room air cleaner should have a CADR pollen rating of 80 or higher.

If you are not sure which particles you want to remove and just want generally cleaner room air, a model with a HEPA filter and a carbon element (also removes odors) is a good overall choice. A multiple-speed model for rapid filtering or for slow quiet operation at night is a plus.

The following companies offer room air cleaners: Blueair, (888) 258-3247,; Essick Air Products, (800) 547-3888,; Holmes, (888) 472-5853,; Kaz, (800) 447-0457,; LakeAir, (800) 558-9436,; and Whirlpool, (866) 698-2538,

Heating incoming water

Dear Jim: Our old concrete patio is crumbling and needs to be replaced. It got pretty warm in the summer sun. What do you think about putting in pipes when the new patio is poured to preheat the incoming water? – Corrine F.

Dear Corrine: Your basic idea of preheating the incoming water so your water heater runs less makes sense. With concrete’s high heat capacity and its relative poor thermal conductivity, it would not be very effective.

A better choice is to make some type of solar collector that gets hotter in the sun, and therefore, transfers more heat to the incoming water. Make sure to install valves to bypass it during the winter.

Send inquiries to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit