Device protects against flooding should water heater spring leak

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. Both valves are interconnected by a sensing tube. The normally closed inlet valve contains a diaphragm which 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 (14.7 psi). Since 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.

The floor tiles in my 11-year-old home seem to be lifting. When we step on them, they make a crunching sound like there is sand under them. What causes this?

Answer: We assume that you are referring to tiles on a concrete slab. Moisture is collecting beneath the tiles and causing them to lift. The crunching sound is probably efflorescence under the tiles. Efflorescence is caused by soluble salts in the concrete slab that dissolve in the water as it migrates through the slab. When the water evaporates, the salts remain under the tiles as an encrustation. This condition can occur even though you do not see standing water on the floor. To prevent the problem, you will have to reduce or eliminate water below the slab with a drainage system around the perimeter of the foundation.