What is HVAC?
HVAC stands for heating, ventilation and air conditioning. It encompasses the technology of indoor and vehicular environmental comfort. HVAC is meant to provide thermal comfort and acceptable indoor air quality using the principles of thermodynamics, fluid mechanics, and heat transfer. HVAC systems provide ventilation, reduce air filtration, and maintain pressure relationships between spaces. This guide will provide a breakdown of how the different systems operate, as well as causes for your AC blowing hot air. We’ll even go into HVAC in Kansas City and the best systems for our climate.
Ventilation is the process of exchanging or replacing air in any space to provide high indoor air quality. Essentially, this process replaces stale air with clean air via natural or mechanical means. Proper ventilation is made possible by temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide and other various gases. This transfer of air sucks out the unpleasant smells and excessive moisture and keeps the interior air moving. Ventilation is the most important factor for ensuring indoor air quality is up to standard.
This type of ventilation is provided by an air handler (AHU), which is used to regulate indoor air quality. Excess humidity, contaminants and odors can be controlled by dilution or replacement with outside air. In more humid climates, more energy is obviously required to extract excessive moisture in the air. Oftentimes, kitchens and bathrooms already have mechanical exhausts that regulate odors and humidity. Your system can vary depending on flow rate (vent size) and noise level. Ceiling fans work by circulating air in a room to make it seem as though the temperature has lowered. This is done by increasing the evaporation of perspiration on the skin. Fans can even be used in the winter to circulate the warm stratified air from the ceiling to the floor.
This type of ventilation utilizes outside air to circulate the indoor air—no fans or mechanisms necessary. Sometimes this ventilation is made possible via trickle vents or operable windows. Another tactic is to allow warm air to rise and flow out of high building openings to the outside. This causes the cooler outside air to be sucked into the low building openings. Though this method may be cost-effective, it doesn’t work as well in climates that are warm and humid. An air-side economizer combines fans, ducts, dampers and control systems to funnel outside air into a building. Natural ventilation is dependent on air change rate or air changes per hour, which is the hourly rate of ventilation divided by the volume of the space. Most buildings and homes require a minimum of four air changes per hour. Natural ventilation also reduces the spread of airborne illness like tuberculosis, mold, influenza and meningitis. Natural ventilation may not be ideal for HVAC in Kansas City unless it’s being utilized during the more mild-weather times of the year, like Spring and Fall.
The heat pump picked up popularity in the 1950’s. They extract heat from various sources (environmental air, exhaust air, ground) and are popular in both warm and cool climates. With heated water and steam, the piping is utilized to move heat into rooms. The modern hot water boiler heating system has a circulator (pump) which moves hot water throughout the distribution system. Radiators, hot water coils, and other heat exchangers transfer the heat to surrounding air. You can even install radiators in the floor to produce floor heat. When water is used for heat transfer, it’s called hydronics. Heated water can also be supplied to the auxiliary heat exchanger for bathing and washing. Warm air is moved throughout a building via duct work systems of supply and return air through metal or fiberglass ducts. These same ducts are tasked with distributing air cooled by an evaporator coil for air conditioning. This air supply is cleaned before it reaches you via air cleaners that take out the dust and pollen particles.
First, the system refrigerant begins as a gas. Then, the compressor pumps the refrigerant gas up to a high pressure and temperature. Once it enters a heat exchanger (aka condenser coil), it loses energy (heat) to the outside, cools and condenses into a liquid. The expansion valve ensures the refrigerant liquid flows at the proper rate. The liquid refrigerant can evaporate once it’s returned to another heat exchanger (evaporator coil). During the evaporation process, the liquid refrigerant absorbs energy as heat from the inside air. From there, it returns to the compressor and repeats the cycle. During this process, heat is absorbed from indoors and transferred outside. This creates cooling. This can also be reversed in climates with dramatic seasonal changes. Using a reversing valve, you can switch from heating to cooling via a reverse flow of refrigerant. This means you can heat and cool a system using only one piece of equipment.
Free Cooling Systems
These systems are incredibly efficient, especially when paired with seasonal thermal energy storage. When these two systems work together, the cold of winter can be released in summer air conditioning. This cold air is stored in either deep aquifers or natural rock masses that are buried beneath the ground and accessed through small-diameter, heat-exchanger-equipped boreholes. Oftentimes, systems with small storages tap into free cooling early in the season and then later utilize a heat pump to chill the circulation coming from the storage. This storage functions as a heat sink when in cooling mode, meaning the temperature increases during the cooling season. With ‘free-cooling mode’, the control system opens the outside air damper and closes the return air damper. As a result, fresh air from the outside is supplied to the system. In the case that the outside air is cooler than the temperature required, the demand is met without using the mechanical supply of cooling. Energy saved! Free cooling systems are a great option for HVAC in Kansas City because of the regions diverse temperature ranges throughout the year.
Where a humidifier might help with your asthma, dehumidification can prevent mold growth in your home. Dehumidification is powered by the evaporator, which operates at a temperature below dew point. When the moisture within the air condenses on the evaporator coil tubes, the moisture collects at the bottom of the evaporator in a pan and is removed by piping to a designated drain or the ground outside. Essentially, a dehumidifier operates like an air conditioner. Instead of controlling the temperature though, it controls the humidity. They’re used most often in basements with a higher relative humidity due to lower temperatures.
By maintaining your HVAC in Kansas City, you ensure that your systems live a long life. All AC systems come with internal air filters (made of lightweight gauzy material) that have to be changed out or cleaned. Environments with high dust levels or furry pets may need their filters cleaned out more often. If you don’t clean out your filter, there will be a lower heat exchange rate—this means you’re wasting energy! Plus, your equipment won’t last as long and your energy bills will increase. If the problem continues and there isn’t enough airflow to de-ice the evaporator coils, the air flow can stop completely. Plug filters that are extremely dirty or plugged filters result in overheating, creating damage and possible fire hazards. You also need to regularly clean the coils (see below), since an air conditioner transfers hear between the indoor and outdoor coils. Condenser coils also need cleaning, otherwise the compressor will suffer damage. The condenser coil discharges the indoor heat and the heat created by the electric motor driving the compressor.
AC Blowing Hot Air
If your AC is blowing hot air, there are a few steps you can take to troubleshoot the problem. Start with the thermostat setting—make sure you’re set to ‘cool’, your fan is on ‘auto’ and your temperature setting is below what the temperature reads on the thermostat by at least five degrees. A dirty condenser unit (outside) may also be the culprit. Check for debris like dirt, tall grass, or leaves that may be blocking the system. The final issue that you can solve by yourself is a dirty air filter. Warmer weather climates should check their filter more often. A professional will need to be called in if a low refrigerant leak or leaky air ducts are the cause of your AC blowing hot air. A low refrigerant leak means you need to get the problem fixed before you add in more refrigerant—otherwise you’re just putting a band aid on the problem. Leaky air ducts alter your system’s cooling process as well. There are ducts are in your walls, attic and basement, so you’ll need to check all of them to pinpoint the leak.
For any HVAC assistance, including cooling and heating, contact us for service you can trust. Our 24/7 availability ensures you never have to be uncomfortable in your own home. HVAC in Kansas City is our specialty, and our highly trained technicians go through over 100 hours of training each year to ensure we deliver the highest quality of service.