Building Automation Knowledge Base

Issue Satchwell RM series Rotary Actuator does not open or close Satchwell MB series Rotary Shoe Valve Body due to incorrect wiring connections. Environment Satchwell RM series Rotary Actuator installed on Satchwell MB series 3-port Rotary Shoe Valve Body. Cause Satchwell RM series Rotary Actuator incorrect wiring connections. Resolution 1.  Check Satchwell RM series Actuator wiring connections. Wiring connections should comply with the following :- Actuator Terminal 1 = Live to OPEN Actuator Terminal 2 = Live to CLOSE Actuator Terminal 3 = Neutral N.B. The Satchwell RM series Actuator must be connected to a controlling switching device such as a Thermostat, Switch, Relay or Programmer providing CHANGEOVER CONTACT switched outputs rated at mains voltage.  2.  Ensure no other electrical device is connected between controlling switching device and Satchwell RM series Actuator. N.B. In such circumstances back feeds can cause the Satchwell RM series Actuator to stall which in turn may result in the electric motor within the Actuator burning out. 3.  Rewire Satchwell RM series Actuator as necessary and observe direction of operation is relative to control signal applied. 4.  Transfer Switches installed within the Satchwell RM series Actuator enable a Pump or Boiler etc. to be switched via the Actuator. Terminal 1 signal transfers to Terminal 1T when Satchwell RM series Actuator is fully OPEN Terminal 2 signal transfers to Terminal 2T when Satchwell RM series Actuator is fully CLOSED    Please check the latest catalog for current equipment.  

Issue Using the TAC I/A BACnet WorkPlace Balance Tool to balance a VAV, when requesting the box drive to Maximum flow, get error "Controller was temporarily busy. Please restart this balancing step” message. What does this mean and how to solve it? Environment BACnet  WorkPlace Flow Balance Tool MNB-V1 MNB-V2 Cause Multiple tools connected to the same VAV controller.  Resolution "Controller was temporarily busy. Please restart this balancing step” message means one of two things – One tool has control of the VAV while another is attempting to connect or the VAV is in the process of completing a balancing step while another balancing function is attempted. Flow balancing should be  accomplished with a single tool connected to a VAV controller.  

Issue Satchwell MB series 3-port Rotary Shoe Valve Body conversion for use as a 2-port Zone Valve. Environment HVAC heating and cooling installations requiring a 2-port Zone Valve having pipework connection size in excess of 3/4" B.S.P. Cause HVAC heating or cooling installations requiring a 2-port Zone Valve Body having a connection sizes in excess of the usual 3/4" B.S.P. HVAC heating or cooling installations requiring a 2-port Valve Body to be installed in place of a 3-port Valve Body originally installed.  Resolution 1  Install plumber's plug in Port 3 of MB series 3-port Rotary Shoe Valve Body. 2. Tighten plumber's plug sufficiently to ensure PN 10 rating of Valve Body is not compromised. IMPORTANT Careful consideration should be given to the use of this conversion method with 3-port Valve Bodies of Plug and Seat construction. Here only "dish nosed" or "hollow ended" plumber's plugs should be installed in Port 3 of the Valve Body. The purpose of this is to prevent fouling of the Plug / Seat assembly within the Valve Body. N.B. In preference a Satchwell VZ 2-port Plug and Seat Valve Body should be replaced by a Satchwell MZ 3-port Plug and Seat Valve Body.

Issue Can an existing UNC-600 serve graphics for a new UNC-520, without adding an Enterprise Server? Environment I/A Series (Niagara) UNC-600 I/A Series (Niagara) UNC-520 Cause Application for serving graphics without adding Enterprise Server. Resolution Yes you can without adding a Enterprise Server. It is recommended that native Niagara objects in the UNC-600 be liked to data points in the UNC-520. This will optimize communication speed and database modifications if need. Remember to set-up the address book and select PEER to PEER. And to watch the resource count of the UNC-600

Issue S-E Forta M700 Actuator unable to be mounted on S-E VGS211F Valve Body . Environment S-E Forta M700 Actuator mounted on S-E VGS211F Valve Body  Cause S-E Forta M700 Actuator unable to be mounted on S-E VGS211F Valve Body due to absence of S-E VGS211F Valve Body Spindle Adaptor. Resolution 1.  Install S-E VGS211F Valve Body Spindle Adaptor prior to installation of S-E Forta M700 Actuator. The S-E VGS211F Valve Body is supplied with a Valve Spindle Adaptor. The Adaptor is illustrated in the S-E Forta M700 Installation Instruction (OFL – 4340 – 001). It is particularly important to ensure that this Adaptor is fitted to the Valve Spindle, as its absence will prevent the M700 Actuator from being mechanically connected to the Valve Body Spindle.

Issue USB-serial adapter recommended for use with DMS Operator interface (OPRIF)  version 11.6.  Environment DMS OPRIF 11.6, DMS-350A and DMS-3500 Cause Lack of serial port on PC. Resolution We recommend the IOGEAR model GU232A. (This is the same adapter we recommend for use with other devices, such as the MSC-LIM, MN-CIM and CBL-002 (DB-9S>DB-9S). NOTE: When using the converter with the MSC-LIM, launch the OPRIF from the LINKERGL.EXE in the DMS folder.

Issue DC1100 / DC1400 displays message "No Sensors Connected" or displays temperature values that are not representative of the temperatures being sensed. Environment DC1100 / DC1400 Discrete Controller and associated Sensors. Cause DC1100 / DC1400 is connected to Sensors having incompatible resistance range. The resistance range of those Sensors compatible with the DC1100 differs to that of the resistance range of those Sensors compatible with the DC1400 "No Sensors Connected" message may appear in the Controller display as a result of the Sensors connected having a resistance that is out of range compared to that of the resistance range that the Controller Sensor Inputs are designed to recognise.  Resolution Check Sensor type connected to Controller. DC1100 Controller is compatible with the following Sensors :- STC 600 D Contact Temperature Sensor                               (Original Drayton Sensor = A704) STO 600 D Outside Air Temperature Sensor                          (Original Drayton Sensor = A702) STP 600 D Pipe Temperature Sensor                                     (Original Drayton Sensor = A703) STR 600 D Room Temperature Sensor                                  (Original Drayton Sensor = A701)   DC1400 Controller is compatible with the following Sensors :- STC 600 Contact Temperature Sensor                                   (Original Satchwell Sensor = DST) STO 600 Outside Air Temperature Sensor                             (Original Satchwell Sensor = DOT)    STP 660 Pipe Temperature Sensor                                        (Original Satchwell Sensor = DWT) STR 600 Room Temperature Sensor                                     (Original Satchwell Sensor = DRT)

Issue AVUE 5304, AVUE 5354, AVUE 5305 or AVUE 5355 Light Duty Actuator does not respond to changes in control signal. Environment AVUE 5304 or AVUE 5354 Light Duty Actuator installed on VZX or MZX Valve Body.. AVUE 5305 or AVUE 5355 Light Duty Actuator installed on Satchwell VEU, MEU or FEU Unit Valve Body.. Cause AVUE 5304, AVUE 5354, AVUE 5305 or AVUE 5355 Light Duty Actuator may not respond to changes in control signal due to self stroking / auto stroking procedure failing to occur when originally installed, or due to manual override having been undertaken without subsequent reset procedure having been applied. Resolution 1.  Check that 0v of 0-10v dc control signal and 0v of 24v ac power supply originate from same source. 2.  Undertake Manual Override Reset. The Manual Override Reset Button is located on the underside of the AVUE Actuator. The purpose of the Manual Override Reset Button is to cause the Actuator to self reference. A reset is required only in the following circumstances. A.  If the Manual Override Access screw on the top of the Actuator has been operated when the Actuator is powered up. B.  If it is necessary to re-align the Actuator to a point of self reference during periods of system maintenance. N.B. The AVUE is designed to reset automatically on restoration of power following a power failure.  It should be noted that it will take approximately 85 seconds (AVUE 5305 and AVUE 5355) or 110 seconds (AVUE 5304 and AVUE 5354) for the self reference procedure to be completed. 

Issue Sigma remote client software has been added to new PC and the client will not connect to the Sigma server properly.  On some occasions the connection occurs but the Sigma Client Menu options are not available. Environment Sigma remote client (up to version 4.04), Windows XP, Windows 2000. Cause Sigma Software up to version 4.04 uses the Windows Share to allow the Sigma Remote Client to connect to the Sigma server.  The Windows share is not working correctly. Resolution 1.  Upgrade to Sigma 4.05 or above as this no longer uses the Windows Share to connect remote clients to the server. 2.1  If the software can't be upgraded then enable file Sigma file sharing between the PC’s by using a common Windows username and password on all the Sigma server/client PC’s. 2.2  Check the firewall/network will allow TCP port 3614 to be passed, unblock if necessary. 2.3 If the PC’s are on a client network then you may have to discuss this with the sites IT people to allow TCP port 3614 to pass through their routers/firewalls. 2.4 If the Sigma communications needs to pass through a firewall then port UPD 49152 will need to be unblocked.

Issue S-E VZ29, VZ39 and VZ49 Unit Control Valve Open / Close status required relative to spindle position. Environment S-E VZ29, VZ39 and VZ49 Unit Control Valve installations. Cause Open / Close status of S-E VZ29, VZ39 and VZ49 Unit Control Valve is not visually apparent Resolution Observe S-E VZ29, VZ39 and VZ49 Unit Control Valve spindle position. S-E VZ29, VZ39 and VZ49  =  Spindle DOWN OPEN / Spindle UP CLOSE   Please check the latest catalog for current equipment.

Issue Importance of correct selection / installation of Satchwell 3-port Valve Body to provide Mixing function or Diverting function. Environment Satchwell 3-port Valve Body to provide Mixing function or Diverting function in heating or cooling circuit.   Satchwell MB, MBF, MJF, MZ, MZF, MZX Cause Incorrect selection / installation  of Satchwell 3-port Valve Body to provide Mixing function or Diverting function may result in poor control, damage to the Valve Body, damage to the Valve Actuator or damage to the hydraulic installation. Resolution Determine which of the following types of hydraulic circuit the Satchwell 3-port Valve Body is to be installed in. Constant Temperature Variable Volume (CT) circuit e.g. AHU Heating / Cooling Coil or Calorifier Coil  Variable Temperature Constant Volume (VT) circuit e.g. Radiator System For Constant Temperature circuit application install Satchwell 3-port Valve Body as follows :- MJF, MZ, MZF, MZX install in RETURN pipework. Port 3 - Connect to Bypass (IN) Port 2 - Connect to Coil Return (IN) Port 1 - Connect to System Return (OUT) MB, MBF install in RETURN pipework. Port 3 - Connect to Bypass (IN) Port 2 - Connect to Coil Return (IN) Port 1 - Connect to System Return (OUT) OR MB, MBF may alternatively be installed in FLOW pipework Port 3 - Connect to Bypass (OUT) Port 2 - Connect to Coil Flow (OUT) Port 1 - Connect to System Flow (IN) For Variable Temperature circuit application install Satchwell 3-port Valve Body as follows :- MJF, MZ, MZF, MZX install in FLOW pipework. Port 3 - Connect to Bypass (IN) Port 2 - Connect to Boiler Flow (IN) Port 1 - Connect to System Flow (OUT) MB, MBF install in FLOW pipework. Port 3 - Connect to Bypass (IN) Port 2 - Connect to Boiler Flow (IN) Port 1 - Connect to System Flow (OUT) OR MB, MBF may alternatively be installed in RETURN pipework Port 3 - Connect to Bypass (IN) Port 2 - Connect to System Return (IN) Port 1 - Connect to Boiler Return (OUT) N.B. It should be noted that the alternative installation methods are valid for the MB and MBF Valve Bodies due to the ROTARY SHOE construction of the MB and MBF Similarly it should be noted that the alternative installation methods are not valid for the MJF, MZ, MZF and MZX Valve Bodies due to the PLUG AND SEAT construction of the MJF, MZ, MZF and MZX . Failure to install MJF, MZ, MZF and MZX Valve Bodies correctly in the pipework may result in VALVE VIBRATION in the pipework caused by WATER HAMMER    INSTALLATION OPTIONS - MJF, MZ, MZF and MZX 3-PORT PLUG AND SEAT VALVES MAY BE INSTALLED TO MIX IN THE FLOW VALVE BODIES USE TWO “IN” PORTS (Ports 2 & 3) AND ONE “OUT” PORT(Port 1)   3-PORT PLUG AND SEAT VALVES MAY BE INSTALLED TO DIVERT (BY MIXING) IN THE RETURN VALVE BODIES USE TWO “IN” PORTS (Ports 2 & 3) AND ONE “OUT” PORT(Port 1)   INSTALLATION OPTIONS - MB, MBF  3-PORT ROTARY SHOE VALVES MAY BE INSTALLED TO MIX IN THE FLOW USING TWO “IN” PORTS (Ports 2 & 3) AND ONE “OUT” PORT (Port 1) 3-PORT ROTARY SHOE VALVES MAY BE INSTALLED TO MIX IN THE RETURN.USING ONE “IN” PORT (Port 1) AND TWO “OUT” PORTS (Ports 2 & 3)) 3-PORT ROTARY SHOE VALVES MAY BE INSTALLED TO DIVERT IN THE RETURN USING TWO “IN” PORTS (Port 2 & 3) AND ONE “OUT” PORT (Port 1) 3-PORT ROTARY SHOE VALVES MAY BE INSTALLED TO DIVERT IN THE FLOW USING ONE “IN” PORT (Port 1) AND TWO “OUT” PORTS (Port 2 & 3)   RELATED INFORMATION - DIVERTING IN THE FLOW It should be noted that some manufacturers produce 3-Port Plug and Seat Valve Bodies specifically designed to DIVERT in the FLOW.  Such Valve Bodies have 1 IN Port and 2 OUT Ports   Please check the latest catalog for current equipment.  

Issue Satchwell ALM series Linear Actuator requires replacement. Environment Satchwell ALM series Actuator installed on Satchwell MJF, MZ, MZF, VJF, VSF, VZ or VZF Series Plug and Seat Valve Body.    Satchwell ALM series Linear Actuators. Cause Obsolescence of Satchwell ALM series Linear Actuator. Resolution Replace Satchwell ALM series Linear Actuator with MV15B-230 Linear Actuator and Linkage Kit and wire as follows :- ALM = MV15B-230 + L7SV (880-0126-000) Linkage Kit. Actuator wiring :- ALM Terminal Number 1  =  MV15B-230 Terminal Number Y2  ALM Terminal Number 2  =  MV15B-230 Terminal Number Y1  ALM Terminal Number 3  =  MV15B-230 Terminal Number N N.B. ALM power consumption  =  4.5 VA          MV15B-230 power consumption  =  12 VA operating and 15 VA Transformer sizing Should the Satchwell ALM series Actuator include a wired Auxiliary Switch (ALA1211) then the following Accessory should also be installed on the MV15B-230 Actuator as appropriate and should be wired as follows :- S2 - MV15B = Two independent 250 volt 10 amp / 3 amp rated SPDT Auxiliary End Point Switches. Auxiliary Switch wiring :- ALA1211 Terminal S1  =  S2 - MV15B Switch 1 Terminal C ALA1211 Terminal S2  =  S2 - MV15B Switch 1 Terminal B ALA1211 Terminal S3  =  S2 - MV15B Switch 1 Terminal A ALA1211 Terminal S4  =  S2 - MV15B Switch 2 Terminal C ALA1211 Terminal S5  =  S2 - MV15B Switch 2 Terminal B ALA1211 Terminal S6  =  S2 - MV15B Switch 2 Terminal A   Please check the latest catalog for current equipment.  

Issue SVT Controller will not operate plant under Auto control following Clock replacement Environment SVT 4201 Optimiser Controller  SVT 4251 Optimiser Controller  Cause SVT Controller will not operate plant under Auto control following Clock replacement due to lack of re-commissioning. Resolution Re-commission SVT Controller using Test method. The absence of plant control may normally be confirmed by lack of illumination of Burner L E D (bottom left corner of SVT)  Test method of re-commissioning may be undertaken as follows: Ensure SVT 4201 Analogue Clock override button is set to AUTO condition and Clock is in an ON period. Ensure SVT 4251 Digital Clock status is set to AUTO condition and Clock is in an ON period. Ensure SVT Manual Override Switch (lower left of SVT) is set to AUTO Note SVT Preheat Selector Switch (lower centre of SVT) setting (scaled 1,2,3,4,5,T) Turn Preheat Selector Switch fully clockwise from Preheat number setting to letter T Turn Manual Override Switch fully anti-clockwise from AUTO setting to O (Off)  Turn Manual Override Switch fully clockwise from O (Off) setting to + (ON) Burner L E D should illuminate and plant should start. Turn Manual Override Switch anti-clockwise from + (ON) setting to AUTO Burner L E D should remain illuminated and plant should continue to run. If plant continues to run then proceed to action L.  If plant remains OFF then return to action A. Turn Preheat Selector Switch anti-clockwise from T position to previously noted SVT Preheat Selector Switch setting.  

Issue CSC 5 Series Climatronic Compensator Controller Battery missing when Controller supplied. Environment CSC 5 Series Climatronic Compensator Controllers. Cause CSC 5 Series Climatronic Compensator Controllers - not all specifications require a Battery to be fitted.  CSC 5252 Climatronic Compensator Controller - has no Clock and therefore requires no Battery to be fitted. CSC 5352 Climatronic Compensator Controller - has a Clock and therefore requires a Battery to be fitted. CSC 5352 Climatronic Compensator Controller - Battery should be packed with Controller when new. The Battery (3.6V Lithium AA) is required to power the Clock whilst the Controller is powered OFF for a period of typically 1 year of continuous use. The typical shelf life of the Battery is 10 years. Resolution If CSC 5252 Climatronic Compensator Controller is to be installed then no Battery is required. If CSC 5352 Climatronic Compensator Controller is to be installed then Battery should be fitted. If CSC 5352 Climatronic Compensator Controller Battery is not packed with Controller then its absence should be reported to the supplier. Please check the catalog for current equipment

Issue Is IPv6 IP Addressing format support by Sigma controllers? Environment Sigma IPv6 IPv4 Cause Worldwide IP addresses are running low and to handle the demand for new IP Addresses the IP protocol has been updated from IPv4 to IPv6 Resolution Currently, Sigma devices do not supported IPv6.  IPv4 is the recommend IP Addressing protocol.

Issue Satchwell FEU 4-port Unit Control Valve Open / Close status required relative to spindle position.  Environment Satchwell FEU 2, 4, 5 and 6 Series 4-port Unit Control Valve installations. Cause Open / Close status of Satchwell FEU 4-port Unit Control Valve is not visually apparent  Resolution Observe Satchwell FEU 4-port Unit Control Valve spindle position. FEU 2 Series  =  Spindle UP OPEN / Spindle DOWN CLOSE FEU 4, 5 and 6 Series  =  Spindle DOWN OPEN / Spindle UP CLOSE

Issue DC1100 / DC1400 displays identical temperatures for all connected Sensors.  It is not uncommon for a temperature of 39 deg C to be displayed for each Sensor connected to the Controller. Environment DC1100 Stand Alone Optimiser / Compensator Controller DC1400 Stand Alone Optimiser / Compensator Controller Sensors compatible with DC1100 :- A701 Room Temperature Sensor A702 Outside Air Temperature Sensor A703 Pipe Temperature Sensor A704 Contact Temperature Sensor STC 600 D Contact Temperature Sensor           (Original Drayton Sensor = A704) STO 600 D Outside Air Temperature Sensor      (Original Drayton Sensor = A702) STP 600 D Pipe Temperature Sensor                 (Original Drayton Sensor = A703) STR 600 D Room Temperature Sensor              (Original Drayton Sensor = A701) Sensors compatible with DC1400 :- STC 600 Contact Temperature Sensor               (Original Satchwell Sensor = DST) STO 600 Outside Air Temperature Sensor          (Original Satchwell Sensor = DOT)    STP 660 Pipe Temperature Sensor                     (Original Satchwell Sensor = DWT) STR 600 Room Temperature Sensor                  (Original Satchwell Sensor = DRT) 39 deg C. Cause DC1100 / DC1400 displays identical temperatures for all connected Sensors.  A Sensor temperature of 39 deg C is a common value displayed. Resolution Check each Sensor is correctly connected to its appropriate "Common" Terminal of the DC1100 / DC1400 Wiring Base Check each Sensor Cable Screen is correctly connected to the Earth Terminal of the DC1100 / DC1400 Wiring Base Check that a good Earth connection exists between the Earth Terminal of the DC1100 / DC1400 Wiring Base and the site Earth Check that a good site Earth is available for connection to the DC1100 / DC1400 Wiring Base. N.B. In the event that the DC1100 / DC1400 continues to display identical temperatures for all connected Sensors following completion of the above checks then it is suggested that the Cold Start procedure is applied to the Controller and the result observed.

Issue S-E VZ29 / VZ39 / VZ49 Valve Body produces excessive let-by.   Environment S-E VZ29 2-port Valve Body controlled by S-E MZ20 series Actuator. S-E VZ39 3-port Valve Body controlled by S-E MZ20 series Actuator. S-E VZ49 4-port Valve Body controlled by S-E MZ20 series Actuator. Cause S-E MZ20 series Actuator Manual Override set to value other than ZERO Resolution 1.  Check S-E MZ20 series Actuator Manual Override facility is set to ZERO. 2.  If S-E MZ20 series Actuator Manual Override facility is set to ZERO then investigate Valve Body condition / duty compatibility. Instances of excessive let-by experienced with S-E Valve Bodies from the VZ29 / VZ39 / VZ49 family may result from the setting of the Manual Override facility on the S-E MZ20 series Actuator controlling it, rather than the Valve Body itself. S-E MZ20A and MZ20B Actuators include a Manual Override facility, comprising a screw, accessed through a hole in the top of the Actuator, which may be raised and lowered by means of a 3mm Allen Key inserted through the hole in the top of the Actuator. The Manual Override position is required to be set to ZERO upon manufacture.  If the screw is not set to the ZERO position prior to dispatch however, then this may result in the Valve Spindle being depressed by the amount of Manual Override applied. Where a Valve Body is letting by excessively, then initially the Actuator Manual Override setting should be checked and reset to ZERO if necessary.  

Issue Satchwell VSF or VJF Valve Body controlled by Satchwell Spring Return Actuator requires replacement. Environment Satchwell VSF or VJF Valve Body installed in Water or Steam Control Valve applications. Cause Obsolescence of Satchwell VSF or VJF Control Valve Body. Resolution STEAM APPLICATION 1.  Replace Satchwell VSF or VJF Valve Body with S-E Two-Port Flanged Valve Body. Where an existing Satchwell VSF or VJF Valve Body is utilised in a STEAM application, then the VSF or VJF Valve Body should be replaced by a suitably sized S-E VGS211F Valve Body, thus enabling steam having a steam inlet pressure up to 1300 kPa and a temperature up to 200 deg C to be controlled. It should be noted however that the face-to-face dimension and overall dimensions of each S-E Valve Body will differ to those of the Satchwell VSF or VJF Valve Body. It should also be noted that the operation of the VGS211F Valve Spindle is the reverse of that of the VSF or VJF Valve Spindle. When the VGS211F Valve Spindle is UP, or in the fully extended position, then the Valve is OPEN. Similarly, when the VGS211F Valve Spindle is DOWN, or in the fully retracted position, then the Valve is CLOSED This will therefore result in the need to replace the existing Satchwell Actuator with the correct model of S-E M700 Actuator, in order to ensure the correct operation of the Valve Body in the event of electrical power failure. It is important that the above limitations are recognised when replacing a Satchwell VSF or VJF Valve Body with a S-E VGS211F Valve Body in retrofit projects. Such limitations do not apply to new projects where a new S-E VGS211F Valve Body and a new S-E  M700 Actuator are being selected, providing of course that an Actuator having the correct spring action in the event of electrical power failure is selected. N.B. Steam Control Valves are normally required to CLOSE in the event of electrical power failure. In the case of the S-E VGS211F therefore the S-E M700 SRSD Actuator should be selected. WATER APPLICATION 1.  Replace Satchwell VSF or VJF Valve Body with S-E Two-Port Flanged Valve Body. A number of alternative models of S-E Two-Port Flanged Valve Bodies are available to replace existing Satchwell VSF or VJF Two-Port Flanged Valve Bodies. It should be noted however that the face-to-face dimension and overall dimensions of each S-E Valve Body will differ to those of the Satchwell VSF or VJF Valve Body.  

Issue Replacement of Satchwell DRT3451 Adjustable Room Temperature Sensor by S-E STR612. Environment Satchwell DRT3451 Adjustable Room Temperature Sensor installations. Cause Obsolescence of Satchwell DRT3451 Adjustable Room Temperature Sensor Resolution Replace Satchwell DRT3451 Adjustable Room Temperature Sensor with S-E STR612 The STR612 provides the same functionality as the DRT3451 differing only in its appearance, dimensions and terminal identification. Equivalent terminal identification is as follows STR612 Terminal 22 (A) = DRT3451 Terminal A STR612 Terminal 23 (C) = DRT3451 Terminal C Connection of STR612 to CZU Fan Coil Unit Temperature Controller STR612 Terminal 22 (A) – connect to CZU Terminal 9 STR612 Terminal 23 (C) – connect to CZU Terminal 10 (CZU Setpoint should be set to 10 deg C)