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Q: I read your response to an air-condition condensation issue on the HGTV Web site. I have a similar question: Is there is a problem caused by too much condensation? The central air unit is in the basement. The condensate drain from the unit in the basement started leaking, and I have been collecting the condensate in a bucket. I feel like there is too much. I collect about five gallons or more a day.

I wonder if this is a sign of a problem with the unit. I thought the evaporation of the condensation across the coil was what created the cooling, and I worry if the condensation is an issue. — DIY fan, New Jersey.

A: It has been humid, but we always seem to get a lot of condensation.

If the coil box is leaking anywhere but the discharge opening, there is a problem with the collection system of the cooling coil. The coil is supposed to cool the air in the ducts to a point below the dew point at which time the moisture trapped between the air's molecules is released. If I remember chemistry, humidity is a measurement of the water vapor between the air's molecules whereas "specific humidity" is the amount or the weight of water vapor in the air. Cold air cannot hold as much water vapor as warm air so by cooling the air at the coil, the air becomes saturated and the water vapor is released as condensate.

The amount of condensate released depends on the temperature at the coil and the amount of water vapor trapped in the air. The engineering formula looks like this: qcond = qair dwlb / 8.33 vda (1).

That is way past what I am able to do, so let's stick to the basics. The coil is not supposed to leak, so something must be broken, blocked or damaged.

There should be a tray or a pan under the coil that is set at an angle toward the drain opening. Dirt trapped on the coil can wash off, blocking the gravity flow of the water, which can clog the drain opening. Or the tray may be damaged or blocked and overflowing, and water may come out of strange places at the coil box.

Annual maintenance by a qualified service technician along with proper filter care can prevent leaks or other unexpected problems.

There are two things you need to be aware of: First, a leaky coil does not necessarily mean you need a new coil. The coil contains the refrigerant, an oily substance that cannot be easily confused with condensate water. If there is no oily substance, the tray or pan is all that needs to be repaired.

In some cases the pan and the coil are fused together. It may be easier and cheaper to replace the entire coil, but you have to be the judge.

Second, we know that a cooling coil can release several gallons of water a day, so it' important to have a secondary catch pan or an air-conditioner shut-off switch when the condensating unit is located above a finished area of the home.

The catch pan's drain pipe should be separated from the coil's condensate drain pipe, and it should drain to a viewable location so that you'll know if you are having a flooding problem. If your catch pan has a shut-off switch, it will be connected to the outside AC unit's circuits. If there is a flooding problem inside the catch pan, the float on the switch will rise tripping the circuits, which automatically shuts down the outside AC. When the AC stops, the condensate flooding stops and the cooling stops.

The warmer-than-normal house will soon get the attention of a homeowner, and there will not be massive water damage from an overflowing system.

I recommend you check the catch pan every cooling season to make sure the drain is not blocked with debris, dirt or insulation and that the float switch is working.

C. Dwight Barnett is a certified master inspector with the American Society of Home Inspectors.