How To...

1. When I had the boiler for our radiators checked, the service man said to pick a temperature and leave it there all the time, not to lower the thermostat at night, because it takes more gas to heat things up in the morning than you save by turning it down. Everything else I read says turn down the thermostat at night. Which is correct?

Silver Spring

There is a reasonable point behind what the service man told you, but there is still a way for you to save energy by turning down the thermostat, according to Doug Anderson of the federal Energy Star program. Radiator systems respond more slowly to changes in thermostat settings than forced-air systems do. So if you were to turn back the thermostat at night, then turn it up when you rise in the morning, it might take too long to come back to the ideal temperature for you to feel any benefit before you leave for work.

The solution is a programmable thermostat, accompanied by a little experimentation so you figure out the time lag with your system. Once you know how long it takes for the temperature to rise to a comfortable level, adjust both ends of the cycle to that amount. If you discover that it takes two hours, for example, set the thermostat to turn down the heat two hours before you go to bed and to turn it back up two hours before your alarm rings. Residual heat in the water should keep the house cozy until you're in bed.

The American Council for an Energy-Efficient Economy, a nonprofit group that has been working in this field for years, estimates that most people save about 2 percent for each degree the temperature is set back for eight hours. So setting back heat by 10 degrees overnight could potentially reduce your heating bill by 20 percent.

This advice doesn't hold where a boiler supplies warm water to heat tubing in a concrete floor. There, the heat should be left at one temperature unless the house will be vacant for a long period (such as a vacation). There would be too much delay in bringing the entire slab up to the comfortable temperature.

2. My single-family home is being overtaken by drain flies. They are concentrated mostly in my laundry/utility room, but quickly spread to every other room in the home.

I have had multiple plumbers and exterminators out, but they weren't familiar with the problem and therefore offered no solutions. I have flushed all the drains, applied various drain cleaners and degreasers, but with no success. How can I get rid of these harmless but annoying pests?

Bristow

Although drain flies may seem only a nuisance, they do feed on sewage and other yucky stuff, so they have potential for spreading disease and shouldn't be ignored. They can also be an early warning problem about leaking sewage pipes or septic systems that have failed.

Ohio State University's entomology department has published a flier on these pests, which resemble minute moths because they have numerous hairs on their bodies. The flier is available at http://ohioline.osu.edu/hyg-fact/2000/2071.html. It recommends treating drains with a product known as DF-5000 Drain Fly Eliminator, also sold as Drain Gel. Not a pesticide, it contains a strain of bacteria that breaks down the grime that drain fly larvae eat. One online source for this product is http://www.pestproducts.com. The site also has tips on how to investigate breeding places, the only sure way to rid your house of the flies.

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Send your questions to Jeanne Huber at home@washpost.com.