How do ptac air conditioners work

Those do two things: improve energy efficiency and promote better indoor air quality. Needless to say, both of those are a major plus. How about a little help finding exactly what you need? Looking for Something? A two speed or three speed fan is used to discharge the cool air to the room. The internal view of the components that made up the self-contained packaged terminal air conditioner unit.

Notice the compressor and the condensing coil at one side and the control at the other side. In this case, the same unit that is being used for cooling during warm weather is now being used for heating during cool weather. The heating cycle is known as reverse cycle where a 4 Way Valve is used to reverse the flow of the refrigerant. Other units come with an auxiliary heater as a supplement to the heating process in the event that the heating capacity is not enough during winter.

Packaged Terminal Air Conditioner Controller. The older units usually use mechanical control with mechanical push buttons to select the mode of operation and fan speed control. Another rotary knob is used to set the desired temperature of the unit. Low initial cost and simplicity, two of the most appealing features of PTAC units, are the primary reasons they are the standard choice for many hotels and dormitory-type facilities.

Typically, designers or contractors install these simple systems and then let the occupants or building owners decide the room temperature. If good temperature control and low initial costs were the only expectations for PTAC units, they would be the perfect option for many facilities. The inability of PTAC units to meet these additional expectations has been the cause of many moisture and mold problems over the past several decades.

Often, the resulting problems end up in court, where any lessons learned are not widely distributed to the hospitality design and construction communities. Myth : PTAC units can provide code-required ventilation air to the occupied space. Reality : PTAC units do not provide code-required ventilation even though this myth is an almost universal belief within the hotel design and construction industries for the following reasons:.

If the design relies on the equipment to meet the ventilation code, then the occupant or guest cannot be allowed to change fan speeds or turn the unit off. The photographs in Figure 2 were taken during the investigation of moisture problems in a location where only the summer months are humid northern West Virginia , and where the PTAC unit design was intended to provide code-required ventilation to the guest room.

Note that the vent damper is open, and the path for ventilation outdoor air is past the outdoor condenser coil and through a washable filter. The ventilation air in many PTAC units does not pass through the cooling coil before being mixed with the return air. This can result in increased room humidity. Reality : PTAC units cannot pressurize building spaces, because in order to do so, the following would have to occur:. This does not happen.

Wind effects can overpower PTAC fans, however, and will actually draw air out through the vent door on the leeward negative pressure side of the building. Guest control of the PTAC can result in intermittent fan operation, however, which will cause periods without positive pressurization even if the above two conditions did occur.

Myth: PTAC units provide good dehumidification under the majority of circumstances and in virtually all climates if operated correctly. Reality : PTAC units do not provide good dehumidification. In order to do so, the PTAC unit would need to meet the following conditions:. Instead, PTAC units are often oversized because of conservative load analyses and the industry belief that temperature control is more important than anything else for guest comfort.

This oversizing often results in insufficient run times to achieve passive dehumidification based upon temperature control only. The refrigerant cools the coil, which removes the heat and humidity of the air.

The air is then released through the unit through fans and a vent. A wall thermostat opens up the possibility of installing a programmable controller with an energy management system and even Wi-Fi compatible options.

These systems are designed to optimize energy use and interact with the power grid. All PTAC units have resistive electric heat. That involves wires that get hot and a fan that blows air across them — like a blow dryer. Many PTACs use only resistive electric heat, but some also have a reverse cycle heat pump. A heat pump works similarly to a window unit air conditioner, except in reverse. It blows hot air into the building and cold air out the back by using a valve that changes the flow of the freon in the unit.

Heat pumps draw percent less wattage than other electric heat units.