Commercial A.C. Repair
Understanding HVAC Technology for Commercial Air Conditioning Repair or Replacement
The many kinds of specialty HVAC technologies used in commercial building applications can often be very different from those used in residential applications. This article will provide you with a list of various kinds of commercial air conditioning systems used in the states today. Before talking to your HVAC contractor it may be helpful to review this list so that you can be educated regarding the solutions your contractor is proposing for your commercial air conditioning repair and system needs.
*Heat Pump: Heat pumps are a good alternative to air conditioners and furnaces for moderate climates due to their energy efficiency. Heat pumps move heat from cool to warm spaces, like refrigerators, making cool spaces cooler and warm spaces warmer. Heat pumps move heat rather than generating heat which can give you space conditioning for a fraction of the cost of conventional heating or cooling systems. The air source heat pump is the most common; it transfers heat between your house and the outside air. This type of pump can cut the amount of electricity used for heating with electricity by 30%-40%. The reverse cycle chiller is an air source heat pump that generates hot and cold water rather than air; it is used with radiant floor heating systems.
*Geothermal: Geothermal heating and cooling systems use a piping system, known as a loop, to make use of the stable underground temperature. The loop circulates water exchanging heat between the earth, the ground source heat pump, and your home, providing cooling, hot water, and heating with great efficiency.
*Chilled beams: The chilled beam is a convection system used to cool or heat large buildings. Water passes through the beam, a heat exchanger, which is suspended near the ceiling. The beam cools the air around it and the dense cool air falls toward the floor. This air is replaced by warm air moving upward, creating a constant flow of convection and keeping the room cool. The heating works similar to a steam radiator. There are active and passive type chilled beams. The active type, also called induction diffuser, pushes air toward the unit through ducts increasing cooling and heating capacity. The passive type, also called radiant or convective, cools through a combination of convection and radiant exchange providing higher thermal comfort levels.
*Unit Ventilators: Unit ventilators can be suspended at or above ceiling level, but are usually located on outside walls. The unit consists of a metal cabinet with a fan assembly, heating coil, filter and controls and dampers. Air is brought into the cabinet through a grille on the outside wall. The unit ventilator mixes outside air with room air and delivers it through a grille at the top of the unit. Typical unit ventilators circulate 1000-1250 cubic feet per minute of air (cfm), with a minimum of 400 cfm being outdoor air. 100% of airflow can be outside air with this unit when needed for free cooling.
*Fan Coil Unit (FCU) and Blower Coil Unit (BCU): A fan coil unit consists of a heating or cooling coil and fan. It controls the temperature of the space where the unit is installed. The units are more economical to install than central heating systems with air handling units or ducted systems. The fan however, can be quite noisy. The unit can be floor mounted or ceiling mounted. Blower coil units are used in bigger spaces.
*Constant Air Volume (CAV): With constant air volume the supply air flow rate is constant, but the supply air temperature varies based on the thermostat setting. There are two commonly used CAV systems; the mixed air and the terminal reheat. The mixed air has two air streams, one for the hottest air temperature and one for the coldest air temperature needed. This system controls the temperature very well, but isn’t great at controlling humidity. The terminal reheat system provides a comfortable environment, but can waste energy. The system cools the air in the unit to the lowest temperature needed within the zoned space.
*Variable Air Volume (VAV): Variable air volume systems vary the air flow rate at a constant temperature, unlike constant air volume systems which do the inverse. The advantages to the VAV system over the CAV system are reduced energy consumption, less compressor wear, better temperature and humidity control, and reduced fan noise. Supply air temperature can be controlled based on cooling/heating needs or reset based on outdoor temperature.
* Variable Refrigerant Flow (VRF): Variable refrigerant flow uses refrigerant as the heating and cooling medium. A single outdoor condenser conditions the refrigerant and serves multiple evaporators or FCUs to condition the space. Evaporators connected to the condensing unit can be in cooling and heating modes simultaneously with the heat recovery option, thus reducing energy consumption required when cooling or heating spaces due to less wasted energy to the condenser water loop.
* Displacement Ventilation: Displacement ventilation distributes cool air at a low level, floor level, and at a low velocity. A heat source causes the cool floor level air to rise. The benefits of the system is improved comfort by the removal of contaminants associated with heat sources and energy savings from reduced air ventilation due to low supply height and high return height.
If your business is in need of commercial air conditioning repair or replacement trust Therma Tech Inc. to provide you with trustworthy, affordable, expert service.