Down to the Bones: How Your Washington, DC, HVAC System Works

August 28, 2017 | Articles
Your Home's HVAC

Washington, D.C., residents need both heating and cooling to keep their homes comfortable. Year-round comfort relies on the right combination of features. Review how common HVAC systems work, so you can build your next installation to perfectly suit your needs.

The Basics of Air Conditioning

Air conditioners rely on refrigerants known as hydrochlorofluorocarbons (or HCFCs if that seems like a mouthful) to cool your home. These HCFCs can transform from a liquid to a gas and back again very easily. When the refrigerant is in its liquid state, it absorbs heat until it turns into a gas. The gas then carries the heat away. When the refrigerant is forced back into a liquid, it expels the heat. By repeating this process, HCFCs can move large amounts of heat from one place to another.

Air conditioning systems feature four essential components: a condenser, evaporator, compressor, and expansion device. Inside the home, the air conditioner’s fans blow air over the evaporator coils. The liquid refrigerant inside the coils absorbs heat from this air and turns to a vapor. The air, now much cooler, returns to the home.

Meanwhile, the refrigerant moves into the compressor, located outside the home. The compressor does just as its name suggests. It compresses the HCFC gas. Now in a highly pressurized state, the gas moves on to the condenser. This part of the system condenses the HCFC so that it releases its heat and returns to a liquid state. Fins on the outside of the condenser unit help the heat escape as it’s released from the refrigerant.

The cool liquid refrigerant heads back into the home where the expansion device will direct it to the evaporator coils in a steady flow. The cycle repeats continuously while your AC system is running until it’s absorbed enough heat to get the home to your desired temperature.

Home Heating Simplified

A standard gas furnace will do an admirable job of keeping your home comfortable, but do you know how it works? The process begins when the thermostat senses the temperature is too low. This signals the furnace to open the gas valve and light the burner. The burner generates warmth in the heat exchanger. Warm air from the exchanger is pushed through the hot-air plenum into the home’s ductwork. From there, it travels throughout the home. Combustion gases generated in the process are expelled through a flue in the ceiling or wall.

Split Systems Vs. Packaged Units

As the name suggests, split systems have components that are split between two locations. The evaporator coil is located inside the house, while the condenser and compressor are in an outdoor unit. The simple layout is energy efficient and easy to configure in nearly any home. It can offer both heating and cooling, so you can manage your home’s temperature year-round with one installation.

Packaged systems house the evaporator, condenser, and compressor in a single cabinet. This is typically placed on a roof, though it can go in any convenient outdoor location. This design is ideal for smaller homes where space is at a premium. Installation is quick and affordable, and the compact system is known for being easy to maintain.

Single Vs. Multi-Stage System Operation

When you’re shopping for a new air conditioner or furnace, you’ll probably see options for single- and multi-stage operations. A system with single-stage operation is either on or off. It blows with the same intensity, regardless of your exact heating or cooling needs. This is usually the most affordable option, thanks to its straightforward operation.

A multi-stage system operates at different speeds. It may have a two-stage compressor with two speeds to choose from, or a multi-stage compressor with three or more speeds. This gives you a more fine-tuned approach to your home comfort.

You may also see variable-speed compressors. These compressors don’t operate at two or three set speeds. Instead, they offer subtle adjustments to the compressor speed that are designed to give you temperature adjustments that meet your comfort needs with as little energy use as possible.

Air-Source Heat Pumps

Air-source heat pumps operate similarly to air conditioners. However, they have the ability to both heat and cool the home. Air-source heat pumps have compressors, indoor and outdoor copper coils, and blowers. When the heat pump is in heating mode, the refrigerant in the outdoor coils pulls heat from the air, evaporates it into a gas, and deposits the air inside the home. In cooling mode, it does the opposite. A reversing valve changes the flow of refrigerant as needed to switch between heating and cooling.

If you have existing ductwork in your home, you can use an air-source heat pump to direct hot or cool air through these ducts. However, heat pumps are also a popular option for ductless heating and cooling. With just a 3-inch hole in the wall, you can connect the interior and exterior units. This makes heat pumps an ideal pick for a garage, sunroom, basement, or other part of the house that’s not connected to central ductwork.

Geothermal Heat Pumps

Geothermal heat pumps draw their heating and cooling from the earth rather than the air. Underground temperatures remain stable year-round. In summer, the temperature beneath the earth’s surface is cooler than the air above. In winter, it’s warmer.

A geothermal heat pump features a series of underground loops that cycle liquid. This liquid either absorbs heat from the earth to deposit in the home, or deposits the home’s heat into the cool ground. Geothermal heat pumps lack the noisy compressor found in standard air conditioners, and thus operate much more quietly. They’re extremely energy efficient, making them an obvious choice if you’re looking for a great way to go green.

HVAC Zoning

HVAC zoning is a method of controlling the home’s ductwork to manage the flow of air to various parts of the home. Each zone has its own thermostat to manage temperatures independently in different parts of the house. Motorized dampers in the ductwork and on the air outlets control the flow of air. The dampers and thermostats work together to customize temperature management in each part of the home.

With a zoned system, you don’t have to spend money heating or cooling parts of the home that are unused. This is particularly useful in a large house. You can direct less air to the bedrooms during the day when they’re empty, and direct air only to the bedrooms at night when the rest of the home is unused. HVAC zoning is possible with any heating or cooling system that uses ductwork.

Dehumidifiers and Humidifiers

Humidifiers and dehumidifiers are helpful air quality features that you can often add directly to your central heating and cooling system. Humidifiers add moisture to the air. They can do this in many ways. Evaporator humidifiers have reservoirs of water and wicking filters that draw the water up, creating damp barriers within HVAC systems. When air blows past the filter, it absorbs some of the humidity.

Steam vaporizers boil water and release the moisture into the air in the form of steam. Ultrasonic humidifiers have diaphragms that vibrate at ultrasonic frequencies, sending water droplets into the air. Impellers have diffusers shaped much like combs. A spinning disc throws water to the diffuser, which breaks it into smaller droplets and sends it into the air.

Dehumidifiers pull moisture from the air. They suck air in toward their cooling coils which absorb some of the moisture from it. The air is then pushed back out, much dryer than before. The dehumidifier collects moisture in a small reservoir. Adding one or both systems to your central heating and cooling can help you carefully manage moisture levels in your home.

There are powerful HVAC options to you, whether you’re shopping for an entirely new system or need a few smart upgrades to improve the installation you have. Contact Griffith Energy Services, Inc. at 888-721-5707 for help choosing the best HVAC components for your Washington, D.C., home. We’ll help you choose the best installation for your budget and comfort.

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