653 Right Thermostat Control
Datasheet

Overview

HVAC control is one of the primary benefits of the Lutron Residential Systems offering. Lutron thermostat controls improve the overall efficiency of a home and enhance  temperature control. Basic knowledge of an HVAC system is helpful in choosing the correct Lutron thermostat control for each application.
This document outlines recommended processes for determining which Lutron thermostat control is best suited for a particular application. These processes help identify  various resources that can aid in the decision making process and serves to define key terms in the HVAC industry.

New Construction or Retrofit Application

Most Lutron thermostat control solutions can be easily installed in a new construction or retrofit application. If the Lutron thermostat control is to be installed in a retrofit  application, there are no pre-install considerations since everything is typically installed already. If this is the case, skip to Find the Existing Thermostats and Check the  Connections Used. Continue with this section if the application is either new construction or if the HVAC equipment is being replaced.
New construction is convenient because the walls are open and easily accessible. Ensure that the proper wire size and number of conductors are run from the HVAC  equipment to the thermostat locations. Lutron thermostats use 18 AWG to 22 AWG (1.0 mm2 to 0.5 mm2 ) solid wire. In an application where a heat pump will be used or  there is a strong possibility of one being used, make sure that 7 conductors are installed. In all other cases, make sure five conductors are installed. Run all wires to the  location where the thermostat will be mounted. Verify that the technician completing the wiring follows the specifications mentioned above.
The HomeWorks Palladiom HVAC controller (e.g., SMC55-RESI, SMC55-HWQS, SMC55-RESI-2) is typically mounted with the HVAC equipment so the wire runs between  those devices and the HVAC equipment are usually short.
The Lutron wireless thermostat (L-HWLV2-WIFI) has an integrated temperature sensor. Like a typical thermostat, they are often wired in the living space and require longer  wire runs. Remote mounting options are available via remote temperature sensors.
Having the correct number of conductors will ensure that there is enough wire to use either of the 24 V~ Lutron control options.
SMC55-RESI/SMC55-HWQS/SMC55-RESI-2, and L-HWLV2-WIFI all require a common wire connection.
This document will help to compare and contrast all of Lutron control solutions in order to help identify the right choice for every application.

SMC55-RESI/SMC55-HWQS/ SMC55-RESI-2 with
HomeWorks Palladiom
Thermostat (HQWT-T-HW)

L-HWLV2-WIFI

Identifying HVAC Equipment

There are a number of methods to identify the type of HVAC equipment that is used in an application. Regardless of the method, identifying the HVAC equipment is the  most important part of determining which Lutron thermostat control should be used in the application.

Compatible?| |
---|---|---
HVAC Equipment| SMC55 Controller| L-1-1WLV2-WIFI
Single stage cool| Yes| T
Two stage cool| Yes| Yes
Single stage heat| Yes| Yes
Two stage heat| Yes| Yes
Packaged rooftop units| Yes| Yes
Heat pump| Yes| Yes
Dual fuel systems| No’| Yes
Geothermal heat pump| No’| Yes
Heat pump with auxiliary electric heat (emergency)| Yes| Yes
Typical variable speed fan (equipment controlled)| Yes| Yes
Multi-zone systems (controllable dampers)| Yes’| Yes
In-floor radiant heat| Yes’| Yes
Line voltage electric baseboard| No| No
Millivolt system| No| No
Proprietary/digital control system| No| No
Variable speed fan (independent relays)| Yes’| No
Humidity sensing| No’| Yes
Humidification control| No| Yes
Dehumidification control| No’| Yes
Ventilation control| No| Yes
Remote temperature sensor| Yes| Yes
Outdoor temperature sensing| No| Yes-
Variable refrigerant (VRV/VRF)| Yes’| No

1. Requires a third-party control.
2. Remote sensor is a Honeywell sensor.
3. Not currently compatible but will be available soon.
4. Fan Coil Unit (FCU) control only.
5. Requires a third-party control. See Application Notes #585 (048585), #627 (048627), and #650 (048650) at www.lutron.com
6. Included with SMC55-RESI version 7302 or newer.

Locate the HVAC Equipment Installation Manual
The installation manual for the HVAC equipment will help to identify the following important information:

• Type of equipment (e.g., heat pump, gas furnace, A / C)
• Number of stages
• Control wiring (thermostat to HVAC equipment wiring)
  To find a printed version of the installation manual, scan the area around the equipment or look for a protective pocket on the actual equipment. If the installation  manual cannot be found, obtain the manufacturer and a model number of the equipment. Use this information to search for the installation manual online.
  See Figure 1 for examples of installation manuals for HVAC equipment. The equipment type and number of stages are identified on the first page.
  

Control wiring is normally found later in the installation manual. The installation manual will demonstrate how to connect the equipment to indoor thermostats. The connections that the thermostat requires will indicate the potential for a Lutron thermostat control to be used as an alternative in the same application. The wire connections  will also reveal if the system uses a proprietary communication protocol between the controls and the HVAC equipment. If this is the case, the use of any Lutron or third- party alternative is ruled out. See below for examples of connection diagrams in installation manuals.
Figure 2 displays typical thermostat connections from the HVAC equipment to the control.

5. If outdoor thermostats (ODT) are not used, connect W1 to W2 and W3.
6. N/A to programmable thermostat.
Figure 3 shows an example of an air conditioner / heat pump that has the capability of using a proprietary communication protocol between the HVAC equipment and a  special control unit. Since this uses a proprietary communication protocol over terminal D, the Lutron thermostat control would not be able to control this application  directly. In some cases, as with the equipment featured below, an auxiliary device can be added for the implementation of standard 24 V-, non-proprietary controls such as  Lutron thermostats. It is important to determine if this is the case before proceeding and it will often be noted in the installation manual for the HVAC equipment.

Find the Existing Thermostats and Check the Connections Used
This section is applicable in a remodel / retrofit application. Remove the thermostat from the wall to expose the wire connections on the rear of the thermostat. Take note of  the connections being made and then reference those connections in the table below. The table contains the common terminal designations for HVAC controls and the  equivalent Lutron thermostat control connections. For more information about specific terminology, refer to Glossary of Key Terms.

Terminal Description| Terminal| SMC55 Controller| L-HWLV2-WIFI
---|---|---|---
Thermostat power or heat only transformer| R or RH| |
Thermostat power or cool only transformer| Rc| R| Rc
Single or first stage cooling| Y| Y1| Y
Second stage cooling| Y2| Y25| Y2
Single or first stage heating| W| W1| W
Second stage heating| W2| W25| W2
Fan relay| G| G| G
Fan relay [for Fan Coil Units (FCUs) only]| G1, G2, G3| G1, G2, G3| n/a
Common’| C| C| C
Changeover/reversing valve 2 2| 0/B| 0/135| 0/B
Emergency heat| E| R AUX’
AUX,| AUX/E
Auxiliary heat| X or AUX| R AUX’
AUX,| AUX/E
Remote/outdoor temperature sensor| Si or Outdoor 1| Blue wire
(conventional)
Black wire (common)| SI
Remote/outdoor temperature sensor 4| S2 or Outdoor 2| Blue/red wire
(FCU changeover) Black wire (common)| Sl
Universal relay for humidification/ dehumidification/ ventilation| U1| n/a| U1

1. Common wire connection is necessary for every application.
2. “O” is used for most heat pumps. It provides power for changeover/reversing valve in cooling mode.
3. “B” is used in Rheem or Ruud systems. It provides power for changeover/reversing valve in heating mode.
4. Sensor connection requires both terminals. It is not a single terminal connection.
5. Included with SMC55-RESI version 7302 or newer.

Read the Installation Manual for the Recommended Thermostats
Reading the installation manual for recommended thermostats is especially useful for new construction applications. A retrofit application often has a thermostat in the space  that can be used to verify the connections. New construction applications do not have a thermostat installed and will not have limitations based on wiring as with retrofit  applications.
In the HVAC equipment installation manuals and specification sheets, the thermostats that are recommended are typically from the same manufacturer. This can lead to the  assumption that only their thermostats can be used, perhaps as a result of a proprietary communication protocol. Despite the recommendation, it is typically not a  requirement and third-party thermostats can often be used. However, it is still prudent to consult an HVAC specialist or contact the HVAC equipment manufacturer’s  technical support before proceeding.
The best practice is to consult an HVAC specialist, look up recommended thermostats, and browse the thermostat installation manual for HVAC equipment wiring diagrams.
In Figure 4, the installation manual refers to document T11-001 which can be found online. If a specific reference document is not mentioned in the installation manual, an  online search can be completed to determine if that document exists.
Reading the installation manual for recommended thermostats is especially useful for new construction applications. A retrofit application often has a thermostat in the space  that can be used to verify the connections. New construction applications do not have a thermostat installed and will not have limitations based on wiring as with retrofit  applications.
In the HVAC equipment installation manuals and specification sheets, the thermostats that are recommended are typically from the same manufacturer. This can lead to the  assumption that only their thermostats can be used, perhaps as a result of a proprietary communication protocol. Despite the recommendation, it is typically not a  requirement and third-party thermostats can often be used. However, it is still prudent to consult an HVAC specialist or contact the HVAC equipment manufacturer’s  technical support before proceeding.
The best practice is to consult an HVAC specialist, look up recommended thermostats, and browse the thermostat installation manual for HVAC equipment wiring diagrams.
In Figure 4, the installation manual refers to document T11-001 which can be found online. If a specific reference document is not mentioned in the installation manual, an  online search can be completed to determine if that document exists.

Number of HVAC Zones

It is important to verify how many zones are in the HVAC system. In a retrofit application, this can easily be done by counting the number of thermostats currently installed.  This is important to determine the right Lutron control for the application.
As seen in the table below, all Lutron thermostat controls can control a single HVAC zone. For example, an application with 3 HVAC zones will need three Lutron thermostat controls.

There is a limit of 32 Palladiom thermostats per QS link even though the overall device limit is 99 devices per QS link.
Each SMC55 controller requires one HomeWorks Palladiom thermostat. Each HomeWorks Palladiom thermostat counts as one device on the QS link. Up to four Palladiom  thermostats can be used in a single zone (one master thermostat and three companion thermostats).
Some multi-zone systems use a non-Lutron zone / damper controller to manage multiple zones throughout the house. Lutron thermostat controls are compatible with these  zone / damper controllers, often through a third-party interface.

Features Desired By the End User

Another consideration when choosing a Lutron thermostat control is to understand what HVAC control and features the customer desires / requires. The table below  includes key product features of Lutron thermostat controls. Feature SMC55 Controller 1 L-HWLV2-WIFI

interoperability
OS link| Yes| No
RF link| No| No
Wi-Fi| No| Yes
System| RadioRA 2| No| Yes
RadioRA 3| No| Yes
HomeWorks QS| Yes| Yes
HomeWorks QSX| Yes| Yes

1. For use with a HomeWorks Palladiom thermostat.
2. Scheduled defined on the thermostat, not in the programming software.
3. Requires HomeWorks software version 11.0 and newer.
4. Connect bridge required only for RadioRA 2 and HomeWorks QS systems.

Glossary of Key Terms

Air Conditioner
A system using refrigerant to cool the air in the living space. The refrigerant gets evaporated within a coil inside the house.
Hot air from the space passes over this coil and the refrigerant absorbs the heat and is piped to a condenser unit which is typically outside the house. The heat is released  outside and the refrigerant is recycled and sent back into the house for further heat extraction.
Air Handler
A device which takes the cooled or heated air and moves it throughout the building via the duct work.
Auxiliary Heat
Heat pump systems can be run in reverse to provide heat but the heat provided may not have enough BTUs to heat the residence during the coldest days of the year in  certain geographical areas. Heat pumps are often supplemented by another heat source, an auxiliary heat source, which is commonly electric. As the temperature falls, even  with the heat mode of the heat pump triggered, the auxiliary heat is also triggered to adequately heat the living space. Both the heat pump and the auxiliary heat are working  at the same time.
Changeover/Reversing Valve
The connection utilized to switch a heat pump system from heat to cool mode, reversing the flow of refrigerant in the system. The connection is either designated with an  “O” for cool or “B” for heat.
Emergency Heat or Auxiliary Only Mode
This is a feature found in heat pump systems. It is used when the heat pump equipment is inoperative. It can be manually triggered to turn on a supplemental heat source,  typically electric, to provide heat for the house until the heat pump is operating again. This is different from auxiliary heat in that only one heating method is running at a  time.
Furnace
A device which generates heat for the living space and distributes the heat via air or water. Some systems utilize electric elements which become hot as current passes through  them. Hot air is then passed over the elements, transferring the heat to the air, and distributed to the rest of the house. Other systems utilize fossil fuels which are  combusted and are used to heat water or heat air in a heat exchanger and the air or water is then distributed throughout the living space.
Geothermal or Ground Source Heat Pump
A system which utilizes the Earth as a source of heat (for heating) or as a heat sink (for cooling). This type of system is often referred to as a ground source heat pump  because geothermal often implies the harvesting of heat from the Earth which is not the case. These heat pumps harvest the energy from the sun that is absorbed by the  surface of the Earth.
Heat Pump
A system which uses a refrigerant to both cool and heat the air in the living space. In cool mode, the refrigerant gets evaporated within a coil that is inside the house. Hot air  from the space passes over this coil and the refrigerant absorbs the heat and is piped to a condenser which is outside of the house. The heat is released outside and the  refrigerant is recycled and sent back into the house for further heat extraction.
In heat mode, the process is run in reverse. Refrigerant gets evaporated outside of the house. Hot air passes over the outside unit and the refrigerant absorbs the heat and is  piped to a condenser unit which is inside of the house. The heat is released inside and the refrigerant is recycled and sent back outside of the house for further heat  absorption.
The switching between modes is performed using the changeover / reversing valve connection.

Line Voltage Baseboard Heat
A system in which a special line voltage capable thermostat switches a baseboard electric heating element on or off based on the current room temperature and set point.
Millivolt Heat Only
A heating system usually implementing gas fired wall or floor heaters to heat the space. The system requires two wires for the special millivolt capable thermostat or a  standard / non-electric heat-only thermostat. It has no connection to any sort of AC power source. The small electrical voltage is produced by using the flame from the pilot light.
Packaged Units
Usually an outdoor installed air handler which has built-in heating or cooling elements. These elements generate the warm or cool air and air is moved into the space via the duct work.
Split System Air Conditioner
An air conditioning system which has two to five pieces including an outdoor mounted condenser and interior evaporator units. A separate piece, called the air handler, moves the air through the space via the duct work.
Stage
A level of operation for a piece of HVAC equipment. A stage can be for cooling or heating. Single stage means that there is one level of output when performing the cooling  or heating stage. To improve efficiency, multi-stage systems use low and high levels as separate stages. When it is desirable to reach the desired temperature faster, a higher  level or second stage will be triggered and efficiency will be lost compared to using the lower level or first stage.
Temperature Averaging
A process by which a thermostat can receive multiple temperature readings from various temperature sensors within a specific space or zone. The thermostat averages the  temperature readings which allows for a more even temperature in the zone. This provides balance by helping to prevent one room from being hotter than another room in  the same zone.
Zone
To improve the efficiency of a system, the entire home is often split into smaller segments called zones. Zones are separate areas of the house which are managed by the same  thermostat. When a zone requires heating or cooling, that part of the system can turn on without running the entire system for the rest of the house. Some systems  may have one zone per floor and others may have one zone per room.

Frequently Asked Questions (FAQs)

Does L-HWLV2-WIFI utilize Clear Connect technology to communicate with a RadioRA 2 or HomeWorks system?

– No, L-HWLV2-WIFI does not have Clear Connect technology. Instead, it utilizes a wireless network connection to communicate to the Lutron system. The thermostat uses a  Total Connect Comfort account with Honeywell to establish a cloud-to-cloud connection with the Lutron Connect bridge, RadioRA 3 processor, or HomeWorks QSX  processor installed in the residence, allowing control via the Lutron mobile application.

Does L-HWLV2-WIFI require a Lutron Connect bridge in order to work a RadioRA 2 or HomeWorks QS system?

– Yes, L-HWLV2-WIFI does require a Lutron Connect bridge. It also requires the Lutron Connect mobile application and a Honeywell Total Connect Comfort account. In  RadioRA 3 and HomeWorks QSX, only the processor is required.

Is it possible for a RadioRA 2 or HomeWorks system to operate with other Honeywell Wi-Fi thermostats via a Total Connect Comfort account?

– Yes, it is possible for other Honeywell Wi-Fi thermostats to integrate with RadioRA 2 or HomeWorks systems using the cloud to cloud integration of the Honeywell Total  Connect Comfort account along with the Lutron Connect bridge, RadioRA 3 processor or HomeWorks QSX processor, and the associated Lutron mobile application.  Currently, only the Honeywell Lyric Wi-Fi thermostat is not compatible.

Does the Nest Learning Thermostat integrate with RadioRA 2 or HomeWorks systems?

– Yes, the Nest Learning Thermostat does integrate with RadioRA 2 and HomeWorks systems. Integration requires a Lutron Connect bridge, RadioRA 3 processor, or  HomeWorks QSX processor, Lutron mobile application, and a Nest account. Note that Nest integration via a Google Nest account is not supported presently.

Can one of the Lutron thermostats control a VRV / VRF system?

– Yes. Palladiom thermostats and SMC55 controllers can control some LG and Mitsubishi VRF systems via LG and Mitsubishi interfaces. HomeWorks systems also include  built-in support of CoolAutomation equipment. This is an interface that allows for control of the VRV / VRF system from HomeWorks controls and system triggers (e.g.,  HomeWorks, Palladiom thermostat). HomeWorks QS systems can also integrate with this equipment via the Commander interface by North Building Technologies.

Appendix A – L-HWLV2-WIFI Diagram

Can be substituted by a RadioRA 3 processor, RadioRA 2 main repeater or HomeWorks QS processor. For RadioRA 2 and HomeWorks QS, a Connect bridge is also  required.

Appendix B – Nest Learning Thermostat Diagram

1. Only one Lutron Connect bridge required per system (not one per processor).
2. Can be substituted by a RadioRA 2 main repeater for RadioRA 2 systems.
3. Both the Connect bridge and HomeWorks QS processor could be substituted by a RadioRA 3 processor or HomeWorks QSX processor.

Appendix C – HomeWorks Palladiom Thermostat Diagram

Appendix D – Common Heating Systems in the U.S.A.
Based on 2015 data

Lutron, HomeWorks, RadioRA, Clear Connect, Lutron Connect, RadioRA 2, and Palladiom are trademarks or registered trademarks of Lutron Electronics Co., Inc. in the US and/or other countries.
All other product names, logos, and brands are property of their respective owners.

Lutron Contact Numbers
WORLD HEADQUARTERS USA
Lutron Electronics Co., Inc.
7200 Suter Road
Coopersburg, PA 18036-1299
TEL: +1.610.282.3800
FAX: +1.610.282.1243
support@lutron.com
www.lutron.com/support
North & South America
Customer Assistance
USA, Canada, Caribbean:
1.844.LUTRON1 (1.844.588.7661)
Mexico:
+1.888.235.2910
Central/South America:
+1.610.282.6701
UK AND EUROPE:
Lutron EA Limited
125 Finsbury Pavement
4th floor, London EC2A 1NQ
TEL: +44.(0)20.7702.0657
FAX: +44.(0)20.7480.6899
FREEPHONE (UK): 0800.282.107
Technical Support: +44.(0)20.7680.4481
lutronlondon@lutron.com| ASIA:
Lutron GL Ltd.
390 Havelock Road

07-04 King’s Centre

Singapore 169662
TEL: +65.6220.4666
FAX: +65.6220.4333
Technical Support: 800.120.4491
lutronsea@lutron.com
Asia Technical Hotlines
Northern China: 10.800.712.1536
Southern China: 10.800.120.1536
Hong Kong: 800.901.849
Indonesia: 001.803.011.3994
Japan: +81.3.5575.8411
Macau: 0800.401
Taiwan: 00.801.137.737
Thailand: 001.800.120.665853
Other Countries: +65.6220.4666
Lutron Electronics Co., Inc.
7200 Suter Road
Coopersburg, PA 18036-1299 U.S.A.
P/N 048653 Rev. E 08/2022
---|---

References

• Lutron GRAFIK Eye QS System Overview
• Lutron Support Center | Lutron

Read User Manual Online (PDF format)

Read User Manual Online (PDF format)  >>

Download This Manual (PDF format)

Download this manual  >>