Water Heater Needs To Sit On Insulated Pad

HOME CLINIC: Our water heater was leaking so we bought a new one. An insulated pad was placed under the new tank. It is pink in color and seems to be a very high-density type of Styrofoam. I noticed writing on one side saying it was combustible and to use with gypsum board. What is this pad and is it safe to use under the water heater?

Also, the water from the old heater leaked out onto the floors and loosened the floor tiles. Several became very brittle and cracked into small pieces. I believe they are vinyl asbestos tiles. What kind of health hazard does this pose for us and our children? We spend a fair amount of time in our basement.

Lastly, why do water heaters use the same electric wire that comes from the breaker box, while other 240 volt appliances (clothes dryer and range) use extra-heavy wire coming out of the appliance? - D.E., Seattle

DEAR D.E.: Good list of questions. Let's start with the first one. The insulated pad under your hot water tank is probably Dow pink Styrofoam. This is a high-density foam intended to have increased resistance to damage from compressive loads. It is much stronger than white Styrofoam (frequently referred to as beadboard). Normally it is used to insulate walls. In that application, it needs to be sheathed by gypsum board to prevent possible fires.

Small quantities of Styrofoam will not sustain combustion under most conditions; however, large surfaces will sometimes sustain fire. It is not likely a small piece placed under your hot water tank could catch fire, or be able to sustain one. Placing a rigid foam pad under a hot water tank is a common practice and required under some rebate programs.

The purpose of the insulation is to reduce heat loss from the tank into the living space, which will occur anytime the tank is hotter than the surrounding space. If you tried to put a sheet of gypsum board under the tank, you would be courting a mess. Gypsum board (sheetrock) will turn into a crumbling mass if it gets wet. From your description, the installation is probably safe. If any doubts remain, consult a professional hot water tank installer.

Second, we spoke with an asbestos-abatement expert at the Department of Social and Health Services about your vinyl-asbestos tile. He said you should just sweep it up and remove any whole tiles by prying them loose. Unless you saw or sand them or otherwise reduce them to dust, they are safe to handle.

Asbestos is dangerous when airborne and inhaled, but the pieces you describe are too large to either remain airborne or be inhaled. Dispose of them by placing in a trash bag with a twist tie and put the trash bags containing the tiles in the trash.

Last, hot water tanks use a different type of wire than other 240-volt appliances because they are hardwired into the home circuitry, while dryers and ranges are plugged into 240-volt outlets by pigtails. Hot water tanks are hardwired because they are plumbed to the household water system. So-called hardwired appliances use solid or single-strand electric wiring. This wire in not intended to be flexed after it is installed.

Different appliances use different amounts of electricity. Those that use a lot of electricity require large wire; those that use less, require smaller ones. If an appliance that demands large amounts of current is using a wire gauge that is too small, the wire may overheat, a fuse could fail, a circuit breaker could be triggered, or a fire could start. Soft-wired appliances such as stoves or dryers require multi-strand wires because they are plugged into sockets and the cords are subject to movement when the appliances are plugged in and out, or are pulled away from the wall for cleaning, servicing, etc. The insulation used on movable appliances also needs to be designed to withstand flexing.

Home Clinic answers questions about home maintenance, repair and energy conservation. It is prepared by the Energy Extension Service, a division of the Washington State Energy Office. It appears Sundays in the Home/Real Estate section of The Times.