Do It Yourself: Find water stain’s source before trying to clean it

Q. We have a large, dark stain on our living-room ceiling that I believe to be caused by water. What can we do about this? Is there a cleaner that will remove it?

A. If you haven’t found and fixed the source of the water that is causing the stain, then that is the first step.

The water comes from above, of course, and could be a roof leak, a leaking plumbing pipe, or condensation from some metal object in a poorly ventilated attic.

If there is access to the attic, you might be able to identify the source of the water. Roof leaks usually show up as stains on the roof rafters, and leaking pipes or condensation are often easy to trace by checking for wet insulation or stained floorboards.

Fixing the source of the water might require professional help, but there is little you can do about the stain until that repair is made.

Eliminating the stain usually requires repainting the ceiling. Some do-it-yourselfers say they have removed small water stains by dabbing with mild bleach solutions or other cleaners, but that is seldom effective.

You also cannot simply roll some ceiling paint over the stain – it will soon “bleed through” the paint and show up again.

To eliminate the stain, you must block it before painting with a stain-killer primer such as Zinsser’s B-I-N, which has a shellac base. For the smoothest painting, the entire ceiling should be primed; if only the stained area is primed, there might be a visible difference between primed and unprimed areas.

The room should be well ventilated when using the primer. When the primer is dry, you can roll on the finish paint.

Q. I have a tank-type electric water heater that is only 6 years old, but recently has been putting out only a small amount of hot water. Do I need a new water heater so soon?

A. Your water heater needs a repair, but should not be ready for the junk heap. Water heaters typically have life spans of 10 to 15 years, but I have known of electric water heaters that lasted considerably longer if well maintained and if the water quality is not destructive.

The problem with your heater is probably a burned-out heating element. Most electric water heaters have two elements, one near the bottom of the tank and one about halfway up.

Most of the water heating is done by the lower element, and that is probably the one that is defective. Replacing a burned-out element can be a do-it-yourself job, but you shouldn’t try it unless you have a manual for the heater with step-by-step instructions.

Each of the elements usually has a small access plate on the side of the heater. You should never tinker with them unless you first turn off the electricity to the heater, and an element should not be removed without first turning off the water to the heater and draining the tank.

Removing and replacing an element usually requires a special socket wrench. The power to the heater should never be turned back on until the tank is refilled with water. If you don’t have a manual or are in doubt about any part of the procedure, it is best to call a water-heater technician.

Although it is likely that the lower element is burned out, a technician will have tools to check it and make sure.