QUESTION: I replaced our 15-year-old functioning-but-energy-consuming dehumidifier with an LG 50-pint model.

There are no guidelines in the manual, and the people at Lowe’s didn’t seem to have an answer when I asked what size to buy. “Isn’t there some sort of square footage involved?” I asked. I was told, “Buy the biggest one.”

Generally, I thought I had a mostly dry basement.

With my new dehumidifier, at the preset level of 50 percent, the reservoir is filled by the end of the day.

So this machine is working, like, all day.

I can’t seem to wrap my head around the concept of what is an acceptable humidity level. Do you know what percentage is recommended?

ANSWER: Was the biggest one also the most expensive? My suggestion is that the next time you are in any store and someone tells you to buy the biggest one, move on to the next store until you find someone who believes in customer service.

Or, at least someone who reads the store’s own literature, because Lowes.com has a fine guide on picking the right dehumidifier for your situation.

Dehumidifiers are rated according to their capacity — the number of pints of water removed during a 24-hour period. Units with 25-, 40-, 50-, and 60-pint capacities are available.

The Lowe’s site uses the Association of Home Appliance Manufacturers’ dehumidification selection guide, based on square footage and moisture levels.

For example, a dehumidifier in a 500-square-foot wet area needs to have a capacity of 14 pints per day.

One 50-pint-capacity dehumidifier I saw advertised claimed it was designed for a medium-size space but then added that it could handle an area of up to 3,000 square feet.

I keep my relatively dry basement at 40 percent relative humidity, using a 60-pint-capacity dehumidifier. Instead of having to dump out the reservoir that holds the collected moisture, I have it draining into a plastic splash guard that empties into the sump.

Questions? E-mail Alan J. Heavens at aheavensphillynews.com or write him at The Inquirer, Box 8263, Philadelphia PA 19101. Volume prohibits individual replies.