HVAC systems do much more than heat or cool air. They are also designed to properly circulate and filter air, which makes them important for ensuring good indoor air quality.
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The thermostat is the brains behind your heater and AC, telling them when to turn on, at what temperature, and for how long. It’s a complicated little device, and even a small fault can lead to significant problems for your home. Whenever your system isn’t performing as it should, a quick check of the thermostat may reveal what the issue is.
Most thermostats use simple electrical sensors to measure air temperature. These sensors come in a variety of forms, including bimetallic strips, wax balls, and glass bulbs filled with gas. When these sensors expand or contract with changes in temperature, they produce electricity that activates a relay back at the HVAC unit. This relay sends power to a fan, the heat exchanger (if heating), or the compressor.
Regardless of what type of sensor they use, most thermostats also have some other features to help you control your system more efficiently. For example, some offer a programmable setting that allows you to set different temperatures for specific times of the day. This can be helpful if you want your system to start heating or cooling earlier when you’re gone from home, or if you prefer to wake up at a cooler temperature during winter.
Other advanced thermostats can adjust for humidity, although this requires proper equipment to be installed. These systems typically have a separate sensor that measures the moisture content of your air, and can also control the fan or a dehumidifier.
If you find yourself contacting an HVAC pro more frequently because your system keeps turning on and off or the temperature in your living space doesn’t match your thermostat settings, a simple problem like low batteries or a tripped breaker may be the culprit. However, if these issues don’t solve the problem, you may need to have your thermostat professionally checked and repaired. An experienced technician will take a look at your thermostat to see what’s causing it to malfunction and make any necessary repairs. They will also inspect your ductwork to see if it’s working properly. If not, the pros can make any necessary repairs to ensure your home is always comfortable and energy efficient.
Ductwork
Ductwork is the system of metal or synthetic tubes that transports heated or cooled air from your home heating, ventilation and air-conditioning (HVAC) equipment to different areas. The condition of your ductwork affects the performance of your entire HVAC system. Inadequately designed or installed ducts can waste energy and cause low indoor air quality.
If you notice that your living spaces are dustier than usual or that your energy bills have increased without an explanation, it could be because of leaks in your ductwork. Ducts can also become contaminated with mold, allergens and other contaminants that interfere with the function of your hvac.
When air ducts are properly designed and maintained, they provide a direct path for heated or cooled air to move throughout the building. The ducts are typically located behind walls and ceilings. The air ducts connect to a plenum at one end and to duct outlets at the other end. The plenum is usually attached directly to the furnace or air conditioning unit. The duct pipes then branch out from the duct trunk to each room of your home or business.
Generally, the air ducts are made of metal or other durable materials such as fiberglass. Ducts should be adequately insulated to help reduce heat exchange. The ducts should also be properly sealed to prevent air from escaping.
Leaking ducts can pull in unconditioned air, which causes the heating or cooling system to work harder than necessary to get the job done. This can also reduce the lifespan of your heating or cooling unit.
Ducts that are twisted, kinked, crushed or torn can create holes in the ductwork. These holes may cause the loss of up to 20 percent of conditioned air. This will increase the load on your system and cause inefficient operation.
Depending on your specific needs, the ductwork in your home or business can be made of rigid or semi-rigid metal, vinyl, wood or other material. Rigid ducts are less expensive and more reliable than flexible ducts, but they can be harder to install in tight spaces. Flex ducts are a great semi-permanent alternative to rigid ducting and have a more pliable shape than rigid metal ducts, but they still offer some resistance to pressure.
Air Filters
Air filters are basically screens that fit into a compartment of your HVAC system to keep pollutants out. They can stop big debris, like dust, pet dander, and pollen, but they’re also designed to reduce wear on your equipment by stopping smaller particles from recirculating. Air filters come in a variety of designs, but they all use similar methods to filter debris out of the system. Basic filters consist of strands of fiberglass (for disposable models) or metal mesh arranged into pleats, while higher-end models use material more like a surgical mask’s, with fabric folded into fine meshes to trap smaller particles before they can recirculate.
Air filtration is measured on a scale called MERV, with 1 being the least efficient and 20 being a true HEPA filter. The MERV ratings of air filters don’t just tell you how well the filter works, but they also affect how much pressure is placed on your HVAC system, which can impact energy efficiency and comfort.
When choosing an air filter, it’s important to know which one you have before you check its MERV rating. Filters with higher MERV ratings can restrict airflow and cause your system to work harder, which may lead to expensive repairs down the road.
Spun fiberglass filters are the most common and typically have a MERV rating between 2 and 12. These filters sieve particles larger than their mesh openings at the surface, where they’re directly captured. Particles that don’t reach the filter’s depth are intercepted by polyester fabrics or cotton folds inserted into the filter, where they are absorbed into the medium and removed from the airflow.
Electrostatic air filters are another popular option and have a MERV rating between 5 and 13. These filters attract charged particles, which they then filter from the airflow. They can be a good choice for people with allergies, but they can also be problematic for those with asthma or other respiratory conditions. These filters often produce high levels of ozone, which can trigger symptoms.
Changing your air filter regularly is the best way to keep it from becoming clogged, which can negatively impact your system’s performance and lead to costly repairs. You can buy replacement filters at any hardware store, but it’s easier to have your HVAC professional take a reading from your ductwork and recommend filters that will be safe for your system.
Compressors
The compressor is the heart of your hvac system. It forces air into extremely high temperatures and pressures, which are then used to cool your home. Compressor problems can cause inefficiency and even damage your system if they aren’t addressed right away. Some common problems include overheating, electrical issues, and refrigerant leaks.
Reciprocating compressors compress air by mechanically changing its specific volume in an enclosed working space that decreases during each cycle. This is achieved by a series of pistons, spirals, or screws that move in and out of a cylindrical chamber, trapping air and forcing it into a smaller volume each time. This type of compressor is commonly found in large commercial air conditioning systems.
Rotary compressors, on the other hand, use centrifugal force to accelerate the movement of air through the unit. They’re used in small to mid-sized hvac systems. A rotor’s spin creates a moving liquid ring along the compressor’s inner walls that forms multiple seals. As the rotor rotates, these seals build up to form compression chambers. The resulting pressurized air is then pushed through the compressor’s output valve.
There are several different types of rotary compressors, including scroll, radial, and twin-screw models. The type you choose depends on your home’s cooling needs, energy efficiency requirements, noise tolerance, and maintenance costs. It’s important to work with a professional when choosing your compressor, as improper system design can lead to high energy consumption and poor performance.
When a rotary compressor starts up, it consumes about 25% of its full load power demand. To reduce this cost, you should install a properly sized storage tank and maintain wide working pressure bands during normal operation.
Another important consideration when selecting a compressor is its energy efficiency, capacity, and reliability. Proper ductwork and insulation must also be in place before installing the unit. The right size compressor will ensure optimal performance and cost savings. Consult with a professional for personalized advice on your specific air conditioning system.