What is a heater hose?

Answer 1

Might as well start at the beginning. Modern car and truck engines create a great deal of heat when their engines are running. In order to keep them from running too hot, a mixture of water and antifreeze is pumped through channels inside the engine, and then out to the vehicles radiator. The radiator runs the hot water through it's thin metal tubes, designed to dissipate heat quickly, and air is allowed to pass between the tubes with the help of a fan, so as to cool the water back down before it reenters the engine, so that it can repeat the process of carrying heat away from the engine.

Ever notice how an engine twists inside the engine compartment, when the throttle is revved ? That's because our vehicles engines are mounted on rubber blocks, (called motor mounts), that absorb engine noise and vibration, and prevent it from being transferred into the vehicle's cabin, where it would be extremely annoying. Our radiators however, are mounted directly to our vehicle's frame. If we used solid metal tubing to connect our engines to our radiators, they would break, the first time we stepped on our gas pedals, due to the side to side movement of our engines when the throttle is hit (caused by engine torque). Rubber radiator hoses flex a bit when we hit the gas, and solve that problem.

So, what is a heater hose? All of this hot water created by friction inside the engine, is put to good use, when heat is desired inside the vehicle's cabin. In order to provide heat for the vehicles occupants, a much smaller "radiator", (roughly 8X12 inches, but vary according to the size of the vehicle), called a heater core, is attached to the engine's cooling system by means of two hoses, called heater hoses. The radiator and heater core are very similar, except for their size, and the fact that while a radiator is used to cool the engine's coolant (antifreeze and water), and therefore the engine, the heater core is used to heat the air that passes through it, inside the vehicle's "heater box", which is a part of the duct work that carries fresh air, air conditioned air, and heated air to the vehicle's cabin, and made to securely hold the heater core inside of that duct work. Heater hoses are much smaller than radiator hoses, (similar in size to a garden hose, but made of much tougher material, in order to withstand constant high heat.) and run from the radiator to the firewall, where they're generally attached directly to the heater core's input and output tubes, with hose clamps. they should be checked from time to time for cracks and other deterioration.