Home Improvement : Cool, but Clammy? Here’s How to Prevent It

QUESTION: Our central air conditioner does not seem to keep us as comfortable as it used to. We’ve made our house more efficient over the years, but it feels a little cool and clammy now. What can we do?

ANSWER: Your problem is not uncommon and there probably is nothing wrong with your central air conditioner. Since you have made your house more energy efficient, your air conditioner has to run less now to keep it cool.

In effect, your air conditioner is now oversized for the cooling needs of your more efficient house. Therefore, it does not run long enough to adequately dehumidify the air for comfort. This often forces you to set the thermostat lower to compensate and this drives up your electric bills.

You can install a new type of heat pipe heat exchanger in your central air conditioner air handler (indoor blower section) and greatly improve your comfort. If you are handy with tin snips, you can install one yourself.

A heat pipe uses no electricity and has no moving parts. It simply draws heat from the return room air immediately before the air reaches the cold air-conditioning evaporator coils. If your air conditioner is old, you can install a new integrated high-efficiency heat pipe/evaporator coil unit.

A heat pipe super-cools the return air as it passes through the cold evaporator coil. Since the air becomes extremely cold, most of the humidity condenses out as water. This produces dry, comfortable air. It is similar to the way a very cold can of soda sweats in the summer.

The other end of the heat pipe is in the cold air stream going back to the registers. The heat that was drawn from the return air to super-cool it, is given back to the cool dry air again on the other side of the coil.

Since the air in your house is less muggy, you can set your thermostat several degrees higher and still be very comfortable. This can really cut your summertime electric bills.

Installing one of the new super-efficient and super-quiet room-size air conditioners also can be effective. This allows you to spot super-cool a room or two that you use most often. Set your central air conditioner thermostat a little higher and save overall without sacrificing comfort.

You can also have your air-conditioning contractor check the air-flow rate through your central system. By slowing down the blower somewhat, the air gets colder and more of the humidity is condensed out. Don’t try this yourself without the advice of your serviceman. Don’t slow it too much.

You can write to me at the address below for Utility Bills Update No. 425 showing product information and manufacturers of dehumidifying heat pipes and coils, model numbers and output ratings of new super-high efficiency room-size air conditioners, and a chart of electricity savings from a thermostat setup. Please include $1.50 and a self-addressed business-size envelope.

Keep Water Heater Temperature Lower

Q: What is the proper hot water temperature to set on my water heater? I have heard that 120 degrees is a minimum, but that seems too hot for showers, especially in the summer.

A: A temperature of 120 degrees is often given as an efficient target. If you can get by comfortably with a lower temperature, set it down. With cooler water, less heat is lost to your house through the water heater tank walls.

In the summer, it’s a double loss because your air conditioner runs longer to remove the wasted heat. Most new dishwashers, the only appliance that needs very hot water, have a water preheater.

Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.