Device Can Prevent Water Heater Leaks

Question: Is there any device available that would protect against a flood in the event my water heater springs a leak while we are away on vacation?

Answer: Yes, a device called Heaterguard consists of a normally closed control valve in the cold-water line and a check valve in the hot-water outlet. The valves are interconnected by a sensing tube. The normally closed inlet valve contains a diaphragm that separates tank pressure on one side and household pressure on the other. The sensing tube is located above the diaphragm.

Consequently, when there is a household demand for hot water, the pressure differential created across the diaphragm causes the valve to open, allowing cold water into the tank. The check valve opens, and water is drawn out as well.

If a leak occurs, about a pint of water escapes as tank pressure drops to atmospheric pressure. Because the sensing tube is above the diaphragm, there is no pressure difference between the valves, so the control valve remains closed. The check valve in the hot-water outlet prevents introduction of air from an open faucet, and the resulting vacuum prevents further leakage from the tank. Little or no water flowing from the hot-water tap notifies the homeowner that there is a problem with the heater.

Heaterguard costs about $50 at plumbing supply houses. It’s manufactured by Boals Control Co., 11 Conejo Circle, Palm Desert, CA 92260.

Adhesive From Parquet Can Be Safely Stripped

Q: I’m removing a parquet floor from terrazzo. How can I remove the parquet adhesive left behind?

A: Try using Peel-Away 5, a stripper formulated for adhesive and coatings removal. According to its manufacturer, it won’t damage terrazzo. After it softens the adhesive, you remove it using a long-handled scraper. If the adhesive is really tough, you might have to scrub it with a brush before scraping it. You can find it at paint stores.

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To submit a question, write to Popular Mechanics, Reader Service Bureau, 224 W. 57th St., New York, NY 10019. The most interesting questions will be considered for future columns.