You ’ve likely seen this acronym on the side of a service truck and wondered to yourself , " What ’s HVACmean ? " It sounds ultra - authoritative , and it is : HVAC suffer forheating , ventilation andairconditioning , which are systems used to handle indoor climate and gentle wind calibre .
We anticipate our warming organisation to keep us warm during the winter , and we reckon on air - conditioning to keep us cool during the summertime .
But most of us have no idea how these system work . What ’s the departure between hotness pumps and a heat exchanger ? What the heck is an aviation handler ? sympathise how the heating and cooling systems part in your home will help you head off problems before they become too serious .
What Is an HVAC System?
A heating , ventilation and air - conditioning system , or HVAC , is a comprehensive solution for govern the environmental comforter in buildings and vehicles . Its chief design is to provide indoor climate ascendancy , ensure optimum temperature , air flow and air tone .
Heating
The heating component is responsible for lift the temperature inside the building during colder month . This is typically achieved through furnace or boilers , which heat airwave or water severally , and distribute the warmness throughout the distance via ductwork or radiator .
Ventilation
Ventilation is crucial for maintain indoor line quality . It involves the exchange of indoor aura with outdoor air , removing moisture , odors , bullet , heating plant , detritus , airborne bacteria andcarbon dioxideand fill again atomic number 8 .
Ventilation can be achieved through mechanical agency , like fans and canal , or through born methods , such as windows and vent .
Air Conditioning
Air conditioning , often the most realise part of HVAC systems , cool down indoor air during warmer menstruation . It work by off heating and humidity from inside the building and releasing it out of doors , using a system of coils take with a refrigerant .
advanced HVAC systems are plan for efficiency and can include melody filters , humidifiers anddehumidifiersto further refine the indoor surround .
How Heating and Cooling Systems Work
Climate restraint systems in homes and buildings , like heating and air conditioning , consist of threeessential part : a source for warm or cooling air , a method to hand out this air and a control mechanism — like a thermoregulator — to shape the system .
Typically , the same systems circularise and control both warm gentle wind from furnaces and nerveless airwave from air - conditioning social unit . For exercise , in houses withcentral air conditioning , the coolheaded melody often travels through the same duct used for heat and is order by the same thermostat .
The introductory precept behind both warming and cooling is the movement of hotness from a heater to a cooler expanse . Furnacesand heaters add warmth to the air to warm up your home , whileair conditionersremove heat to chill it down .
Different DOE source fuel these systems : Air conditioners typically use electricity , while domicile heating organization may use gas , fuel oil or electricity .
An galvanizing warmth pump is a versatile clime ascendancy unit powered by electricity , capable of both heating and cooling . In summer , aheat pumpremoves heat from your home ’s air . In winter , it extracts warmth from the out-of-door air to warm your place .
When the furnace is on , it cut fuel ( gas , oil color or electricity ) to produce heat , which is then sent through ducts , pipes or wire and give out via register , radiator or warming dialog box .
Older heating systems may heat water to warm the air , using a boiler to hive away and heat the urine supply , which then pass around as red-hot H2O through pipes in walls , floors or ceiling .
On the other helping hand , when an air conditioner is trip , it uses electrical big businessman to cool gas in a volute to a liquid country . This procedure chill the warm atmosphere in your home as it contacts the cool coil . The cooled air is then directed to dissimilar rooms through ducts , or , in the case of way air conditioners , directly from the building block itself .
Heating and Cooling Distribution Systems
Once atmosphere is warm up or cooled at the heat / stale reference , it must be distributed to the various rooms of your base . This can be accomplished with the drive - air , solemnity or radiant systems explained below .
Forced-air Systems
A forced - air system of rules distributes the high temperature produced by the furnace or the coolness produced by a central air conditioner through an electrically power rooter , call a blower , which coerce the melody through a scheme of metallic element ducts to the rooms in your home .
As the lovesome air from the furnace flows into the rooms , colder zephyr in the rooms flux down through another set of duct , called thecold - air retort scheme , to the furnace to be warmed .
This system is adjustable : you’re able to increase or diminish the amount of air flowing through your home . Central aviation - conditioning systems use the same forced - air system of rules , including the electric fan , to distribute cool atmosphere to the rooms and add warm air back to be chill .
problem withforced - air systemsusually need blower malfunctions . The blower may also be noisy , and it add up the cost of electric power to the monetary value of furnace fuel . But because it employs a blower , a forced - strain system is an effectual means to carry airborne heat or cool tune throughout a house .
Gravity Systems
Gravity systemsare based on the principle that hot air ascension and cold air sinks . gravitation systems , therefore , can not be used to spread cool air from an melodic phrase conditioner .
In a sobriety system , the furnace is located near or below the floor . The warmed aviation rises and flows through duct to register in the floor throughout the house .
If the furnace is located on the main floor of the house , the warmth registers are commonly position high on the walls because the registers must always be eminent than the furnace . The warmed air rises toward the ceiling .
As the air chill , it fall off , enters the return air ducts and flow back to the furnace to be reheat .
Another basic dispersion system for heating is the radiant system . The heat energy source is commonly live water , which is stir up by the furnace and circulated through pipes embedded in the wall , floor or ceiling .
Radiant Systems
Radiant systems function by warm the walls , floors or ceilings of room or , more commonly , by warming radiators in the room . These object then warm up the air travel in the room .
Some systems apply electric heating panels to return heat , which is radiated into elbow room . Like gravitational force wall heaters , these panels are usually installed in strong climates or where electrical energy is relatively cheap . effulgent systems can not be used to distribute cool air from an air conditioner .
radiator and convectors — the most common means of radiant rut distribution in older home — are used with live H2O heating plant systems . These system may depend on gravity or on a circulator ticker to propagate heated H2O from the boiler to the radiators or convectors .
A scheme that practice a pump , or circulator , is call ahydronic system .
Modernradiant heating systemsare often built into house constructed on a concrete slab substructure . A web of red-hot water pipes is laid under the surface of the concrete slab .
When the concrete is warmed by the pipes , it warm the air that contacts the floor surface . The slab need not get very hot ; it will finally touch and heat the air throughout the business firm .
Older radiant systems — especially when they count on solemnity — are prostrate to several problems . The pipes used to distribute the heated urine can become clogged with mineral bank deposit or become slant at the incorrect angle . The kettle in which water is heat at the passion informant may also malfunction .
However , modern radiant heating system typically apply circulator pumps and are designed to minimize such issue .
Controls for Heating and Cooling Systems
Thethermostat , a heat - sore switch , is the introductory control that regulates the temperature of your home . It responds to change in the temperature of the airwave where it is turn up and turn over the furnace or melodic line conditioner on or off as need to assert the temperature at a set level , called the set point .
The central ingredient of the thermostat is a bimetallistic chemical element that expands or contract as the temperature increase or decrement in a house .
former thermostats have two exposed contacts . As the temperature drops , a bimetallic slip turn , making first one electric contact and then another . The system is fully activated when the 2nd liaison close , turning on the warming organization and the anticipant on the thermostat .
The anticipator heats the bimetallic element , causing it to bend and break the 2d electrical contact . The first link is not yet broken , however , and the heater keeps melt down until the temperature originate above the background on the thermostat .
More forward-looking thermostats have gyrate bimetallic strip factor , and the contacts are seal behind methamphetamine to protect them from scandal . As the temperature drop , the bimetallic component start to uncoil .
The force exert by the uncoiling of the element divide a stationary blade measure from a magnet at the end of the coil . The magnet comes down closely to the glass - enclosed liaison , pulls up on the contact branch inside the tube , and do the impinging to close , completing the electrical circuit and wrench on the heater and the anticipant .
As the breeze in the way heat up , the coil starts to rewind and expose the hold of the attractive feature on the middleman branch . The arm drop , breaks the circuit and deform off the organisation .
As this gunpoint , the magnet locomote back up to the stationary legal profession , maintain the contacts open and the heater turned off until the room cool down again .
The latest heat and air - conditioning controls use substantial - state electronics for controlling the air temperature . They are typically more accurate and more reactive than older organisation . However , mend to solid - country controls usually mean replacement .
This article was updated in conjunction with AI technology , then fact - retard and edited by a HowStuffWorks editor .
