Dear Jim: I went to a home center store to find a programmable thermostat to save energy. There were many with different specifications, and I had no idea what I needed. How can I tell which features are important? – Bob Y.

Dear Bob: Installing a programmable thermostat provides about the best economic return of any energy conservation improvement you can make. When it is programmed properly for your family’s schedule, there really is no reduction in your comfort. In fact, sleeping in a cooler bedroom is actually healthy.

Setting the furnace thermostat lower at times during winter and higher during summer results in significant savings on your utility bills.

Depending upon your climate, the savings range from 1 percent to 3 percent for each 10-degree setback period of eight hours during winter. The percentage savings when air-conditioning is even higher.

As you found, there are many programmable thermostats from which to select. Although more expensive ones may have more features, a relatively simple one will meet the needs of most families. As with most electronic products, prices have dropped dramatically, so don’t think an inexpensive one will not be adequate.

The first decision to make is how many setback periods you desire per day. The simplest thermostats allow for just one setback period per day, usually overnight. If you also want to set the temperature back during the day when everyone is either at work or school, select a thermostat with four setback periods per day. This offers more flexibility for future schedule changes and it is the most commonly installed type.

Next, determine how many different daily setback schedules your family needs. If each weekday and weekend schedule is the same, you can select an inexpensive 5+2 thermostat. This 5+2 designation means there is one schedule for five days of the week and another schedule for the two weekend days.

If you need a different schedule on Saturday and Sunday, select a 5+1+1 thermostat. For the option to have different schedules every day of the week, select a seven-day thermostat. For simple programming, they all offer a repeat button to copy one day’s schedule to another day. Some of the better thermostats also allow you to program the indoor humidity level and alert you when to change the air filter.

If your television DVD player is still flashing “12:00,” select a thermostat with a feature that allows you to snap off the cover and take your time to program it in an easy chair. Another nice feature is a generic preprogrammed setback schedule so you can begin using the thermostat immediately. Once you read the manual, you can modify the schedule.

The following companies offer programmable thermostats: Bryant, 800-428-4326, www.bryant.com; Honeywell, 800-468-1502, www.hotfreshcool.com; Hunter Fan, 888-830-1326, www.hunterfan.com; Lux Products, 856-234-8803, www.luxproducts.com; and Trane, 877-880-3381, www.trane.com.

Dear Jim: I have been having problems with the plumbing. We now have metal pipes, some in the attic. I would like to switch to all white PVC pipe. Is this safe for drinking water and what about the cold temperatures? – Lynn G.

Dear Lynn: First of all, standard white PVC pipe is used only for drain pipes. Supply lines must be metal or a different type of plastic, usually CPVC. No piping material can withstand the expansion forces of freezing water. Although PVC drain pipe is easy to install and relatively inexpensive, I would stay with metal and just repair it. The heavier metal pipe deadens the sound of water rushing through it.