Heating Plug

BEHAVIOR

These plugs provide electrical power to block heaters and interior heaters. They allow drivers to get electric power from an external

supply at home or in parking lots.

HABITAT

Some plugs hang down from beneath the front grill, waiting to be

inserted into an electrical outlet. Others are built into the car fender.

HOW IT WORKS

In cold weather, engines start with greater difficulty and operate at

lower efficiency until warmed up. The fuel doesn’t vaporize as easily

when it is cold, so the car initially exhausts more unburned fuel,

adding to air pollution. And pistons are shaped so they work optimally when heated, which means that they don’t fit the cylinders optimally when they are cold. This results in a further loss of energy. Engine oil is more viscous in cold weather, which makes it more difficult for engine parts to move. And the chemical reaction in the battery that converts stored chemical energy into electricity needed to power the starter occurs more slowly. To prevent all of these inefficiencies, drivers use engine heaters.

When parking in cold climates drivers plug their cars into a source of electricity. In some places these sources have timers that either cycle on and off (to save power) or that a driver sets so the car is heated before the intended departure. 

The plugs connect to block heaters under the hood. The heater warms up the engine and helps it start. It also cuts air pollution by making the engine operate more efficiently when first starting. The heaters are often inserted into “freeze plugs” in the engine block. These are expansion holes in the block so the engine can better withstand expansion of liquids during extremely cold weather. A variety of alternative heating systems are available. Heaters for warming the inside of the car can also be connected to the heating plug. These can either sit on the floor of the car or be mounted inside the car.

INTERESTING FACTS

Andrew Freeman invented the block heater in 1946. His device (Patent #2487326) was a heating element inside a bolt. The heating bolt could replace one of the head bolts in the engine so it didn’t require any

other modifications to the engine.

All rights reserved

Published by Chicago Review Press, Incorporated

814 North Franklin Street

Chicago, Illinois 60610

ISBN: 978-1-55652-812-5

Printed in the United States of America

5 4 3 2 1

Library of Congress Cataloging-in-Publication Data

Sobey, Edwin J. C., 1948–

A field guide to automotive technology / Ed Sobey.

p. cm.

Includes index.

ISBN 978-1-55652-812-5

1. Automobiles—Popular works. 2. Mechanics—Popular works. I. Title.

TL146.5.S63 2008

629.2—dc22

2008046620