Unitary and Room air Conditioners & Heat Pumps
ASHRAE Technical Committee 8.11

Scope of TC 8.11

TC 8.11 is concerned with products for use in comfort cooling and/or heating systems. The factory engineered vapor compression systems include: (1) unitary equipment which generally requires the field engineering of the product mounting and ducting, piping and electrical connections, (2) room air conditioners such as window mounted units and ductless split systems and (3) packaged terminal equipment. Specifically excluded are unitary combustion engine driven systems.


The ASHRAE Handbook is published in a series of four volumes, one of which is revised each year, ensuring that no volume is older than four years.  The Handbook can be purchased at the ASHRAE Bookstore by clicking on this link.

This TC is responsible for the following chapters in the handbook:

HVAC Systems and Equipment: Unitary AC/Heat Pumps
Unitary air conditioners are factory-made assemblies that normally include an evaporator or cooling coil and a compressor/condenser combination, and possibly provide heating as well. An air-source unitary heat pump normally includes an indoor conditioning coil, compressor(s), and an outdoor coil. It must provide heating and possibly cooling as well. A water-source heat pump rejects or extracts heat to and from a water loop instead of from ambient air. A unitary air conditioner or heat pump with more than one factory-made assembly (e.g., indoor and outdoor units) is commonly called a split system.

HVAC Systems and Equipment: Room AC, PTACs
Room air conditioners are encased assemblies designed primarily for mounting in a window or through a wall. They are designed to deliver cool or warm conditioned air to the room, either without ducts or with very short ducts (up to a maximum of about 48 in. [1220 mm]). Each unit includes a prime source of refrigeration and dehumidification and a means for circulating and filtering air; it may also include a means for ventilating and/or exhausting and heating.

The ASHRAE HVAC SYSTEMS & EQUIPMENT HANDBOOK may be purchased from the on-line bookstore by clicking on the highlighted text.

HVAC Applications: Residences
Space-conditioning systems for residential use vary with both local and application factors. Local factors include energy source availability (present and projected) and price; climate; socioeconomic circumstances; and availability of installation and maintenance skills. Application factors include housing type, construction characteristics, and building codes. As a result, many different systems are selected to provide combinations of heating, cooling, humidification, dehumidification, ventilation, and air filtering. This chapter emphasizes the more common systems for space conditioning of both single-family (i.e., traditional site-built and modular or manufactured homes) and multifamily residences. Low-rise multi-family buildings generally follow single-family practice because constraints favor compact designs; HVAC systems in high-rise apartment, condominium, and dormitory buildings are often of commercial types similar to those used in hotels. Retrofit and remodeling construction also adopt the same systems as those for new construction, but site-specific circumstances may call for unique designs.

The ASHRAE HVAC APPLICATIONS HANDBOOK may be purchased from the on-line bookstore by clicking on the highlighted text.

Comment on the Handbook: ASHRAE welcomes your comments on the Handbook or a specific Handbook chapter.  To submit a comment about any aspect or part of the Handbook series, you can use the Handbook Comment Form.

Review a Handbook Chapter: To provide your feedback about a specific Handbook chapter, you can answer the brief survey questions on the Handbook Chapter Review Form.


Technical committees develop and sponsor technical sessions at the winter and annual conferences. Information about their future technical program is discussed at each TC meeting and at the TC’s Program Subcommittee meeting

ASHRAE publishes papers and transactions from presentations at its conference events. In addition, ASHRAE records most of the seminar sessions from its conferences on DVD. These DVDs are ideal for use at chapter meetings, in university courses, or company lunch and learns. Products available from the most recent conference may be found here.


Technical Committees are responsible for identifying research topics, proposing research projects, selecting bidders, and monitoring research projects funded by ASHRAE. Information about their specific research program is discussed at each TC meeting and at the TC’s Research Subcommittee meeting.

This TC has the following ongoing research projects:

RP-1721:  Oil Return and Retention in Unitary Split System Gas Lines with HFC and HFO Refrigerants

TC 8.11 Unitary and Room Air Conditioners and Heat Pumps. Co-Sponsored by: 3.04 Lubrication, 10.3 Refrigerant Piping, Controls and Accessories

In split system air conditioning and heat pump systems, it is critical to compressor reliability that line sets are sized to ensure oil return to the compressor.  In Chapter 1 of the ASHRAE Refrigeration Handbook design rules to provide guidance on this matter are provided. However, the current tables need to be updated for the latest HFC-oil combinations as well as HFO-oil combinations to come.  The goal of this project will be to collect sufficient data to develop normalized rules that will allow design engineers to confidently specify line sets for all current refrigeration-oil combinations as well as future combinations in cooling and heating applications.

RP-1733:  Develop Design Criteria for Psychrometric Air Sampler and Mixer Apparatus for Use in ASHRAE Test Standards

TC 8.11 Unitary and Room Air Conditioners and Heat Pumps

Psychrometric chambers are utilized by manufacturers in the design and rating of air conditioners and heat pumps and by the certification laboratories that perform the federally mandated audits of that equipment sold in the United States.  Psychrometric air samplers and mixing apparatuses are utilized to both control and measure the bulk temperature and humidity conditions in both the indoor and outdoor chambers.  This project would develop design recommendations and methods for validating a sampler/mixer combination that would provide the most accurate bulk temperatures and humidities at the following critical locations: indoor air inlet, indoor air outlet.  Sampler/mixer setups are almost always custom fabricated and, thus, having good guidelines is critical to reducing uncertainty and improving correlation between facilities.


RP-1743:  Effect of Inlet Duct and Damper Design on ASHRAE 37/116 Fan Performance and Static Pressure Measurements 

TC 8.11 Unitary and Room Air Conditioners and Heat Pumps

The use of an inlet duct and damper are required by DOE federal test procedures and AHRI standard 210/240 but ASHRAE standard 116 does not address the use of an inlet duct and damper connection to the Unit Under Test.  This research will quantify the effect of the inlet duct/damper on the blower system and measurement system.  It will also develop specific guidelines or create a compensation method that addresses the use of the duct and damper.  This guideline or compensation will improve consistency between OEM's, academia, and test labs that does not exist today, as well as provide a method to install inlet duct and dampers without negatively impacting the measured performance such that measured laboratory performance is more representative of as installed in the field.


RP-1785:  Refrigerant Charge Modeling in Coils for Residential Split Systems

TC 8.11 Unitary and Room Air Conditioners and Heat Pumps. Co-Sponsored by: TC 6.3 Central Forced Air Heating and Cooling Systems, TC 8.04 Air-to-Refrigerant Heat Transfer Equipment

For unitary split systems especially for residential applications, accurate modeling of refrigerant charge inventory is critical to predicting equipment performance at design and off-design conditions. Lack of good charge modeling capability is an industry-wide problem that impairs the ability of equipment models to reflect actual field performance across a range of ambient conditions. In this project, it is desired to develop a process for collecting coil charge data and to obtain detailed, baseline data on charge during cooling and heating operation to allow for the evaluation of existing correlations and make modeling recommendations.



ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry. ASHRAE publishes the following three types of voluntary consensus standards: Method of Measurement or Test (MOT), Standard Design and Standard Practice. ASHRAE does not write rating standards unless a suitable rating standard will not otherwise be available. ASHRAE is accredited by the American National Standards Institute (ANSI) and follows ANSI's requirements for due process and standards development. Standards may be purchased at the ASHRAE Bookstore.

This TC is the cognizant committee for the following standards:

Proposed Standard: SPC 15.2P: Safety Standard for Air-conditioning and Heat Pump Systems in Residential Applications

ANSI/ASHRAE Standard 16: Method of Testing For Rating Room Air Conditioners, Packaged Terminal Air Conditioners and Packaged Terminal Heat Pumps for Cooling and Heating Capacity

ANSI/ASHRAE Standard 37: Methods of Testing for Rating Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment

ANSI/ASHRAE Standard 58: Method of Testing for Rating Room Air Conditioner and Packaged Terminal Air Conditioner Heating Capacity

ANSI/ASHRAE Standard 116: Methods of Testing for Rating Seasonal Efficiency of Unitary Air-Conditioners and Heat Pumps

ANSI/ASHRAE Standard 206: Method of Testing for Rating of Multi-Purpose Heat Pumps for Residential Space Conditioning and Water Heating

This TC is co-cognizant with TC 6.6 on the following standard:

ANSI/ASHRAE Standard 137: Methods of Testing for Efficiency of Space-Conditioning/Water-Heating Appliances that Include a Desuperheater Water Heater

Other Activities

TIP: If MTG involvement add here otherwise leave blank.

This TC participates in the following MTGs

Lower Global Warming Potential Alternative Refrigerants
This MTG is established to coordinate TC/TG/TRG technical activities to help transition the HVAC&R industry to sustainable lower Global Warming Potential (GWP) alternative refrigerants. The MTG will further request participation from US EPA and AHRI. The MTG responsibilities include suggestions for research, development and presentation of technical programs of all types on alternative lower GWP refrigerants, suggestions for Life Cycle Climate Performance (LCCP) systems evaluation for different applications, development of lower GWP solutions for different applications, and a special publication detailing aspects of LCCP applied to the HVAC&R fields. 

Avoided Sources Energy Consumption Due to Waste Heat Recovery and Heat Pump Technologies
This MTG will coordinate development of credible quantification methodologies of the avoided electric power generation and/or primary energy consumptions resulting from the application of heat pump and waste energy recovery technologies. 


ASHRAE Technical FAQs are provided as a service to ASHRAE members, users of ASHRAE publications, and the general public. While every effort has been made to ensure their accuracy and reliability, they are advisory and provided for informational purposes only, and in many cases represent only one person’s view. They are not intended and should not be relied on as an official statement of ASHRAE. Technical questions not addressed may be submitted to the ASHRAE Technical Services department at tse@ashrae.net

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