Heater core
From Wikipedia, the free encyclopedia
A heater core is a radiator like device used in heating the cabin of a vehicle. Through the use of heated coolant from the vehicle's engine, the heater core puts out heat that is then blown into the passenger compartment of the vehicle.
Contents |
[edit] How it works
The internal combustion engine in the vast majority of modern cars and trucks is cooled by water, which is pumped through the engine by the water pump and then to the radiator to give off its heat to the air. However, some of the hot water is pumped through the heater core instead.
The heater core itself is a small radiator that is usually located under the dashboard of the vehicle. It consists of conductive piping that is coiled within aluminum fins to increase surface area. When the heated coolant reaches the heater core through hoses, the coolant enters the heater core at the inlet, travels through the coiled piping, and then exits at the outlet and returns to the water pump.
The fan for the vehicle's ventilation system forces air through the heater core's fins, transferring heat from the coolant to the air, which is then blown into the vehicle through vents at various points.
[edit] Control
Once the engine has warmed up, the coolant is kept at a more or less constant temperature by the thermostat. The temperature of the air entering the vehicle's interior can be controlled by using a valve limiting the amount of coolant that goes through the heater core. Another method is blocking off the heater core with a plastic door, directing part (or all) of the incoming air around the heater core completely, so it does not get heated. Some cars use a combination of this system.
Simpler systems allow the driver to control the valve or door directly (usually by means of a rotary knob). More complicated systems use electronics to control the valve or doors.
Cars with dual climate function (allowing driver and passenger to each set a different temperature) may use a heater core split in two, where different amounts of coolant flow through the heater core on either side to obtain the desired heating.
[edit] Air conditioning
In a car equipped with air conditioning, outside air is first forced through the air conditioner's evaporator coil. This can be thought of as a heater core filled with very cold gas, which cools rather than heats the incoming air. In order to obtain the desired temperature incoming air may first be cooled by the air conditioning and then heated again by the heater core.
[edit] Engine cooling function
Because the heater core cools the heated coolant from the engine it can act as the radiator of the engine. If the radiator is working improperly, the operator may turn the heat on in the passenger cabin, resulting in cooling the engine coolant and then cooling the engine. This idea only works to a certain degree, the heater core isn’t large enough nor does it have enough cold air going though it to cool large amounts of coolant significantly.
[edit] Possible Problems
The heater core is made up of small piping that has numerous bends. Clogging of the piping may occur if the coolant system is not flushed or if the coolant is not changed regularly. If clogging occurs the heater core will not work properly. If coolant flow is restriced, heating capacity will be reduced or even lost altogether if the heater core becomes blocked. Control valves may also clog or get stuck.
Another problem that may occur is if one of connections to the heater core begins to leak. This may first be noticable by smell (ethylene glycol is widely used as coolant and has a sweet smell), later it may cause (somewhat greasy) fogging of the windshield above the windshield heater vents.
Electrolysis can cause excessive corrosion leading to the heater core rupturing. Coolant will spray directly into the passenger compartment followed with white colored smoke, this can create a large driving hazard.
Because the heater core is usually located under the dashboard inside of the vehicle and is enclosed in the ventilation system's ducting, servicing it often requires disassembling a large part of the dashboard, which can be time-consuming and therefore expensive.
[edit] Air cooled engines
Engines that do not have a water cooling system can not use a heater core; one alternative is to guide air around the (very hot) engine exhaust manifold and then in to the vehicle's interior. Temperature control is achieved by mixing with unheated outside air.
[edit] See Also
