Skip to main menu Refrigerators and air conditioners both contain heat pumps. In a refrigerator, heat is moved from the food storage sections and discharged to the kitchen air. Air conditioners work the same way — they move heat from the inside of a building and discharge it to the outside air. Conventional or air source heat pumps differ from those in a refrigerator or air conditioner because they are reversible — they can concentrate heat from the outside air and move it inside to provide warmth, as well as move heat out of the building to provide cooling. To do this, air-source heat pumps (and central air conditioners) need a large outside unit to exchange heat with the outdoor air. Geothermal Heating and Cooling Systems In a geothermal heating and cooling system, the heat pump is connected to the building by a distribution system — most commonly air ducts. And the heat pump is connected to the earth through a series of pipes called a “loop”  The system exchanges heat with the earth, meaning that no noisy or unsightly outdoor unit is needed.

All heat pumps use a vapor compression cycle to transport heat from one location to another. In heating mode, the cycle starts as the cold liquid refrigerant within the heat pump passes through a heat exchanger (evaporator) and absorbs heat from the low-temperature source (fluid circulated through the earth connection). The refrigerant evaporates into a gas as heat is absorbed. The gaseous refrigerant then passes through a compressor where it is pressurized, raising its temperature to over 180 degrees F. The hot gas then circulates through a refrigerant-to-air heat exchanger where the heat is removed and sent through the air ducts. When the refrigerant loses the heat, it changes back to a liquid. The liquid refrigerant cools as it passes through an expansion valve, and the process begins again. Although heat pumps are complex internally, they are marvels of compact design for reliability. Some include features such as additional heat exchangers for water heating, and microprocessor-based automatic controls and protection devices.

You might also be interested in The Importance of A Matching Systemhow to pump down an ac unitDucane heating and cooling equipment is always the right choice. window ac unit electricity usageWe use components chosen for their durability, then test and inspect every piece of equipment for quality before it ships.best ac heat window unit Explore the full Ducane product line » A new HVAC system is a big decision for any homeowner. Learn more about energy efficiency and choosing the right dealer, so you’ll feel good about your decision for a long time. The right choice is the one that comes with plenty of resources behind it. Whether you’re looking for product literature or warranty registration, we’ve got you covered.

Churning with voltage and resembling an explosion at the wire factory, the breaker panel exudes mystique. But it's just a big switch, filled with other smaller ­switches, which lead to the switches that any home­owner can fearlessly flip. Doing so conjures a current of electrons that runs along copper wires, energizing our appliances, lights and modern lives. Breaker-panel literacy isn't only for voltage veterans who recite the National Electrical Code. Even if all you wonder is whether your humble hot tub dreams are electrically attainable, or why the toaster oven kills the kitchen lights—the panel has a thing or two to tell you.NEUTRAL AND HOT WIRESCurrent flows from the panel toward the load along the hot wires and returns along the neutral. Each hot wire's copper tip ultimately connects to its control switch at the circuit breaker, and each neutral connects to a common terminal called a bus bar.BREAKER SIZESMain breakerThis is the on/off switch to the entire breaker panel. A 200-amp breaker is appropriate for a home upwards of 2000 square feet.

Smaller buildings can use 150-amp or 100-amp; small homes and subpanels can use as little as 50-amp.Double-pole breakerUses the entire 240 volts available to the panel. The 15-amp and 20-amp breakers often handle baseboard heaters, 30-amp serve water heaters and electric dryers, 40- and 50-amp are for electric ranges, and the 70-amp could serve a large air conditioner or a subpanel.Single-pole breakerThe 15-amp and 20-amp are all-purpose breakers, running everything from lights and outlets to garage-door openers.15-amp AFI breakerArc-fault-circuit-interrupter breakers can prevent fires caused by accidental electrical discharge.WIRE GAUGE12-gauge wireCommon for low-demand connections to light switches and outlets, attached to either 15- or 20-amp breakers.14-gauge wireToo thin for anything other than 15-amp breakers under small loads.10-gauge wireAppropriate for a two-pole 20-amp breaker or a single-pole 30-amp breaker.8-gauge or 6-gauge wireUsed for 40-, 50- and 60-amp two-pole breakers;

Also used to serve subpanels.GROUND WIRESGrounding prevents a conductor not meant to carry current (such as the metal side of a clothes dryer) from causing injury if it's energized by a frayed hot wire. In a properly grounded system, appliances and metal boxes connect back to the grounding bus of the breaker panel. From there, the system is grounded to the earth via buried ground rods.HOW ELECTROCUTION HAPPENSVentricular fibrillation, the erratic, lethal spasm that occurs as electric current passes through the heart, happens when both of a person's hands touch hot and neutral conductors, causing the current to complete its circuit through the chest. In a ground fault, current can flow into a single hand, zapping the heart as it passes through the body on its way to the ground. When changing live fuses in the old days, electricians worked with one hand while keeping the other in their back pocket--this spared the heart by isolating the current to the nerves of the one hand in the fuse box.

Found in electrical reference books everywhere, the Ohm's law wheel simplifies conversions between watts, volts, ohms and amps. The most important calculation for a consumer is voltage times amperage, which equals wattage—an appliance's power requirements—and the basis of the unit in which electricity is sold. As home-brewed electricity gets more sophisticated, expect to see items now sold as separate hardware—such as solar panel inverters and AC/DC disconnects, or generator subpanels and transfer switches—merge into single, standard parts, which are easier to install and understand.Installing a Backup Generator: In a power outage, a backup generator provides electricity to designated circuit breakers. Natural gas or propane fuels the generator's engine, which spins an alternator to create a magnetic field that sends current to the home. It's critical that no electricity from the generator back-feeds to the grid—linesmen working to restore power could be electrocuted. An automatic transfer switch isolates the generator's electricity to keep it off the grid until power is restored.

Then the generator shuts down and the transfer switch reverses.Wiring Wind Turbines or Solar Photovoltaics: Solar panels and wind turbines feed DC power into an inverter, which converts it to AC for home use. AC and DC disconnect switches allow parts to be isolated for service. These systems constantly back-feed to the grid, but during a blackout—to some grid-tied customers' surprise—their power can't be used. One solution: Store power in a battery backup system. Inverters like Outback Power's Flexpower One cut equipment costs with prewired battery connections and circuit breakers. New micro-inverters convert DC to AC at the panel, eliminating DC wiring runs.Some benefits consumers could see upon completion of a national smart grid are already available in products like Computerized Electric Systems' Smart Panel. Computer hardware hacked onto a standard breaker panel allows this tool to monitor individual circuits, transfer and balance loads between power sources, or manage power remotely.