Jeanie Wong asked:




When performing home upgrades or buying new appliances such as heaters, volts, watts, and BTUs should be factors to consider. Some of you may have noticed that the outlet used to plug in your desk lamp may not be the same as the outlet behind your refrigerator, and without understanding volts, watts, and BTUs, you could be stuck with a heater that doesn’t produce enough heat to warm your area, or worse yet, you may find yourself with a heater that won’t fit in your standard two-pronged outlet.

Voltage

Voltage is measured as the root mean squared value between two slots or holes in an electric outlet of the sort typically mounted in a wall. The purpose of an electrical outlet is to provide an area for you to plug in various electrical appliances in order to supply them with power. Most standard power outlets in the United States are of the 120 volt variety, which have spots for two plugs, and are rated for 15 amps. Therefore, for these standard type outlets, you will be able to use any of the standard 120 volt heaters. However, it is very important to keep in mind that these ratings cannot be exceeded, as the outlet could be damaged or a fire could be started. In addition, if your outlet is only rated for 15 amps, you cannot have a 14 amp heater and other appliances running at the same time on the same circuit, or it will trip the breaker.

With that in mind, larger appliances are powered through 240 volt plugs, and cannot be powered through standard plugs. If they were fed by a 120 volt supply, they would need more than 20 amps of current running through the wires. In other words, the voltage from one hot wire to the other (called line to line voltage) is 240 volts, and the voltage from either wire to the neutral center-tap (called line to neutral voltage) is half that, or of the 120 volt variety as discussed above. These 240 volt outlets can also be found in garages, building sites, and other industrial areas, and this is done to provide the safer, 120 volt power to outlets that need to supply less than 2.4 kilowatts (as opposed to appliances like clothes dryers, which can pull 4 kilowatts).
While a 240 volt garage heater is significantly more efficient and powerful than a 120 volt space heater, this may not be necessary for your home. Though most space heaters are 120 volts, some wall heaters designed for home use are rated at 240 volts and are just as powerful as garage heaters.

Watts

A watt is an SI (metric) unit of power equal to one joule of energy per second. In terms of wattage, almost all 120 volt space heaters are rated up to 1500 watts at the maximum setting, and there is a 10/1 ratio of watts to square feet heated. Therefore, a 1500 watt space heater (120 volts) will be able to heat an area of 150 square feet, and a garage heater rated at 5,000 watts should be able to comfortably heat an area over 400 square feet.

Btus

In terms of Btus, or British Thermal Units, this is also a unit of energy that is used globally in heating and air conditioning industries, but is not commonly used scientifically. Nonetheless, in North America, the term Btu describes the energy value of fuels, and is also used to describe the power of heating and cooling systems such as heaters. When used as unit of power, Btus per hour is the commonly used term, and refers to the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. To convert watts to Btus and vice versa, here are the conversion ratios:

1 watt = approximately 3.41 Btu/hour

1000 Btus/hour is approximately 293 watts

For additional information on voltage, wattage, and BTUs in regards to heating, consult the manufacturer of the heater you wish to purchase, or contact an electrician.

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Michael Russell asked:




How often do you drive past a home or other building and notice the air conditioner? Probably never, unless it is a window air conditioner that looks like it doesn’t belong there. True air conditioning means not only controlling the temperature, but reducing the humidity and purifying the air. Air-cooling is simply forcing cool or cold air into a room, space or building. For the purpose of this article, the terms will be interchangeable. The simplest way to describe it works is the same way your refrigerator keeps food cold.

That would be a fair enough explanation, if you know how a refrigerator keeps things cool. You do know that almost everyone has a refrigerator. You know they make a very quiet noise every few minutes. You know things stay cold and fresh longer. The refrigerator isn’t that complex. It circulates a refrigerant through a system of coils. The noise you hear is a compressor. The compressor compresses the gas refrigerant into a liquid. The liquid then moves through the coils and absorbs heat. We will go into greater detail shortly.

Many homes have air conditioner units in the back or side yard. Some have the window air conditioner, which is effective for cooling a smaller area. Office buildings and other larger buildings have the units on the roof or in large metal structures containing a system.

No matter what the size or the shape, most all air conditioners function the same way. As we said, it works essentially the same as your refrigerator. The principal is evaporation. Both the refrigerator and the air conditioner unit use a refrigerant that, in its normal state, is a gas. The gas may be one of several types or composition, but it is commonly referred to as Freon. The process of cooling the inside of a refrigerator, or for an air conditioner to cool a building space, is a cycle.

The first piece of the air conditioning system is the compressor. The compressor does just that, it compresses the refrigerant gas. The process makes the refrigerant become hot and, of course, under pressure. The now hot gas circulates through coils on the outside of the refrigerator or building and dissipates the heat. The heat dissipating cools the refrigerant gas back into a liquid. After the refrigerant becomes a liquid it goes through another piece of the system called an expansion valve. Running through the expansion valve produces evaporation and the refrigerant becomes cold and at low pressure. The cold gas continues through the interior of the refrigerator or building via coils. The cold, low-pressure refrigerant attracts and absorbs heat inside a refrigerator. In an air conditioner, a fan propels the cold air throughout the area or building. The cycle starts then all over again.

There is little doubt that most people look at air conditioning and air cooling as a welcome miracle. It is a simple process of converting a refrigerant gas to a hot liquid under pressure, then changing it to a low pressure-cooling agent to absorb heat; keeping us and our food cool.

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