Dear Jim: We always have some rooms which are too hot or cold. Is there anything we can add on to the furnace to control temperatures in each room so everyone is comfortable without driving up the utility bills? – Paul J.

Dear Paul: It sounds as if your home would benefit from adding a zoning system to your furnace and central air conditioner system. This allows you to set different temperatures in different rooms. The comfort effect is similar to having an individual heating and cooling system in each room.

Since the kitchen, laundry room, play and work rooms are more active areas, they are more comfortable when kept cooler. Bathrooms are usually kept a few degrees warmer. You will set different room temperatures during the summer.

Some zoning systems allow you to also vary the rooms’ temperatures throughout the day. For example, the living room temperature is increased in the evening when it is used. The bedrooms can be kept warmer at bedtime and morning, but cooler during the day. The kitchen stays cooler overnight.

By keeping the room temperatures in the comfortable range only when you are using them, less energy is required to keep your house warm during winter and cool during summer. This can cut your year-round utility bills by 10 to 20 percent and increase the life of your furnace and air conditioner.

Zoning kits are simple. They include thermostats in rooms or zones – a group of rooms – which are wired by safe low-voltage wire to the main controller. This is connected to mechanical dampers that fit in the ducts. When the thermostat in a chilly room calls for heat, the furnace starts. Dampers in the ducts to other rooms stay closed so heat goes to only the chilly room.

The simplest, least expensive zoning systems may have just two zones with several rooms in each. These use dampers that switch from fully opened to fully closed positions. A two-story home may have one first-floor and one second-floor zone. Other systems have dampers for most rooms in the house.

The most sophisticated systems use modulating dampers that vary the open duct area instead of simply being all or nothing. This provides more even room temperatures. If your home has a temperature variation between the first and second floors, consider a system with automatic recirculation.

The most comfortable zoning systems have an automatic changeover feature to switch from heating to cooling during spring and fall. These may run the central air conditioner briefly during the day to cool only the kitchen and then start the furnace in the evening to efficiently heat only the bedrooms.

Write for (instantly download – www.dulley.com) Update Bulletin No. 589 – buyer’s guide of 12 zoning system manufacturers listing number of zones, type and size of dampers, control-comfort features, and a utility bills savings chart with zoning. Include $3 and a business-size SASE, and send to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244.