- Data Brochure 274_D 11/12 Boiler Control 274 The Boiler Control 274 operates up to four on/off boilers to provide outdoor reset operation, domestic hot water and setpoint operation with priority. When operating as a tN4 System Control, the 274 can connect with up to 24 tN4 devices on a single boiler bus. The 274 has primary pump sequencing capabilities along with a flow proof or combustion air damper proof demand.
How to Use the Data Brochure This brochure is organized into three main sections. The Control Settings section of this brochure describes the various items that are adjusted and displayed by the control. The control functions of each adjustable item are described in the Sequence of Operation. They are: 1) Sequence of Operation, 2) Installation, 3) Control Settings and 4) Testing and Troubleshooting. Table of Contents User Interface ...............................................................
Display Number Field Item Field Displays the current value of the selected item Displays the current item selected Menu Field Displays the current menu Status Field Displays the current status of the control’s inputs, outputs and operation Buttons Selects Menus, Items and adjusts settings Menu Item Symbol Description PRIMARY PUMP Displays when primary pump 1 or primary pump 2 is in operation BOILER PUMP Displays when the boiler pump 1, 2, 3, or 4 are operating BOILER Displays which boiler stage i
Access Level The access level restricts the number of Menus, Items, and Adjustments that can be accessed by the user. The Access Level setting is found in the Miscellaneous (MISC) Menu. Select the appropriate access level for the people who work with the control on a regular basis. There are three Access Level Settings: • User (USER): Select this access level to limit the highest number of settings available to the end user.
Terminal Unit Setting in Adjust Menu Select the appropriate terminal unit in the adjust menu. This will change the shape of the characterized heating curve to better match the heat transfer properties of that specific terminal unit. Hydronic Radiant Floor (HRF1) A heavy or high mass, hydronic radiant floor system. This type of a hydronic radiant floor is embedded in either a thick concrete or gypsum pour. This heating system has a large thermal mass and is slow acting.
Outdoor Design Setting in Adjust Menu Boiler Design Setting in Adjust Menu The outdoor design temperature is typically the coldest outdoor air temperature of the year. This temperature is used when doing the heat loss calculations for the building and is used to size the heating system equipment. If a cold outdoor design temperature is selected, the supply water temperature rises gradually as the outdoor temperature drops.
Boiler Minimum Setting in Adjust Menu The boiler minimum is the lowest temperature that the control is allowed to use as a boiler target temperature. During mild conditions, if the control calculates a boiler target temperature that is below the boiler minimum setting, the boiler target temperature is adjusted to at least the boiler minimum setting.
Fixed Lead & First On / First Off Manual Differential In some applications, it may be desirable to have the first boiler fire first at all times while the firing sequence of the remaining boilers is changed using Equal Run Time Rotation. This rotation option is selected by setting the Fixed Lead / Off DIP switch to the Fixed Lead position.
Boiler Alarm For the Boiler Alarm item to appear in the Adjust menu, the Relay must be set to Alert. If no temperature increase is detected at the boiler supply sensor within this delay period, the Alert relay will close and the control will display the Boiler Alarm error message. All boilers continue to operate if this error is present. To clear the error, press and hold the up and down buttons simultaneously for 5 seconds while viewing the error message in the View menu. Combustion Air (C.A.
DHW Differential Setting in Adjust Menu Mode OFF / No DHW Generation Due to large differences between the heating load and the DHW load, a separate DHW differential should be used whenever a DHW Demand is present. This will improve staging and boiler cycling. When using a DHW Sensor, a DHW Demand is registered when the DHW sensor drops 1/2 of the DHW Differential setting below the DHW setting. The DHW Demand is satisfied once the DHW Sensor rises 1/2 of the DHW Differential setting above the DHW setting.
Mode 3 - DHW in Primary/Secondary with No Priority When a valid DHW Demand is present, the DHW relay (terminal 17) and Primary Pump relay (terminal 18) turn on. Heating zones are unaffected by DHW operation. This mode can be used if the DHW tank is piped in parallel and a DHW valve is installed (need to use an external relay to power the valve with 24 V (ac) since the DHW pump output is a 120 V (ac) powered output).
DHW Priority Override Setting in Adjust Menu DHW Mixing Purge DHW Priority Override applies to DHW MODE 2 and 4, as well as Mode 5 if there is a tN4 device with DHW. It prevents the building from cooling off too much or the possibility of a potential freeze up during DHW priority. When set to auto, the priority time is calculated based on outdoor temperature. At or below the design outdoor temperature, 15 minutes are allowed for DHW priority. At or above 70°F, 2 hours are allowed for DHW priority.
Setpoint Operation Section F Setpoint operation is only available when DHW Mode is set to Off. The control can operate to satisfy the requirements of a setpoint load in addition to a space heating load. A setpoint load overrides the current outdoor reset temperature in order to provide heat to the setpoint load. Setpoint Demand Setpoint Demands come from one of two sources: a Powered Setpoint Demand, or a tN4 Setpoint Control.
Mode 3 - Setpoint in Primary/Secondary with No Priority Whenever a Setpoint Demand is present, the primary pump is turned on and the boilers are operated to maintain the setpoint target. Automatic Priority Override 2 hours Mode = 3 Setpoint 15 mins Primary Pump 70°F (21°C) Design Temperature Conditional DHW Priority Mode 4 - Setpoint in Primary/Secondary with Priority Whenever a Setpoint Demand is present, the primary pump is turned on and the boilers are operated to maintain the setpoint target.
Energy Management System (EMS) Section G The control can accept an external DC signal from an Energy Management System (EMS) in place of the outdoor sensor. The control converts the DC signal into the appropriate boiler target temperature between 50°F (10°C) and 210°F (99°C) based on the EMS Input Signal and Offset settings. To use the external input signal, the EMS / Demands DIP switch must be set to EMS.
Pump Operation Section H Primary Pump Operation Stand-by Operation The control includes two primary pump outputs with capability for sequencing. Primary pump sequencing is activated through a DIP switch. Only primary pump 1 is operated when pump sequencing is turned off, while primary pumps 1 and 2 are operated in stand-by mode when pump sequencing is turned on. The control only operates one primary pump at a time. A flow proof device can be used to detect when stand-by pump operation is required.
Flow Proof Delay Setting in Adjust Menu Primary Pump Purge The control waits a period of time to receive a flow proof demand from the time the primary pump turns on. If the control does not receive a flow proof demand within that period of time, the primary pump turns off and the stand-by primary pump (if active) turns on. The control then waits that period of time again for the stand-by primary pump to prove flow. If flow is not proven, the stand-by pump turns off.
Setting the Schedule Section K To provide greater energy savings, you can operate the control on a programmable schedule. The schedule is stored in memory and is not affected by loss of power to the control. If a tN4 network is detected the control can become either a schedule member or schedule master. Schedule Types Control (CTRL) Schedule (tN4 present) • 5-11: Repeats on a weekly basis. However, it breaks the week into Saturday and Sunday followed by the weekdays.
If the building is not up to temperature at the correct time, the BOOST setting should be lengthened and the setback timer should be adjusted accordingly. If the building is up to temperature before the required time, the BOOST setting should be shortened and the setback timer should be adjusted accordingly.
Installation Caution Improper installation and operation of this control could result in damage to the equipment and possibly even personal injury or death. It is your responsibility to ensure that this control is safely installed according to all applicable codes and standards. This electronic control is not intended for uses as a primary limit control. Other controls that are intended and certified as safety limits must be placed into the control circuit. Do not attempt to service the control.
Boiler Demand To generate a Boiler Demand, a voltage between 20 V (ac) and 260 V (ac) must be applied across the Boiler Demand terminals (21 and 22). DHW Demand To generate a DHW Demand, a voltage between 20 V (ac) and 260 V (ac) must be applied across the DHW/Setp and Com Dem terminals (23 and 24). The Pump Sequencer DIP Switch must be set to Off and DHW MODE must be set to 1 through 5.
Outdoor Sensor (tekmar 070) Connect the two wires from the Outdoor Sensor 070 to the Com and Out (2 and 3) terminals. The outdoor sensor is used by the control to measure the outdoor air temperature. Note: If an Outdoor Sensor 070 is connected to a tekmarNet®4 thermostat in the system, it is not required to be connected to the control. 2 3 Com Out + Outdoor Sensor 070 Boiler Supply Sensor (tekmar 082) Connect the two wires from the Boiler Supply Sensor 082 to the Com and Boil (5 and 4) terminals.
Wiring the Boiler Pumps ) (RELAY TYPE = Boiler pump Terminals 7-8, 9-10, 11-12 and 13-14 are dry contacts. No power is available from these terminals. These contacts can be used to turn on individual boiler pumps. Wire line voltage to one side of the relay. The other side of the relay goes to one side of the boiler pump and the remaining side of the boiler pump goes to neutral. 7 8 Relay 1 Boiler Pumps 120 V (ac) Combustion Air / Alert Contact (C.A.
Terminals 2 – 6 Testing tekmar Sensors To test the sensors, the actual temperature at each sensor location must be measured. • Use a good quality digital thermometer with a surface temperature probe for ease of use and accuracy. Where a digital thermometer is not available, strap a spare sensor alongside the one to be tested and compare the readings. • Disconnect each sensor from the control. • Test the sensors resistance according to the instructions in the sensor Data Brochure D 070.
Terminals 21 – 25 Testing the Demands 1. Remove the front and bottom cover from the control. 2. Use an electrical test meter to measure (ac) voltage between the Boiler Demand terminals (21-22) or the DHW / Setpoint Demand terminals (23-24) or the Proof Demand terminals (24-25).
Rotate / Off Fixed Lead / Off Use the Rotate / Off DIP switch to enable the Equal Run Time Rotation feature. This feature Changes the firing order of the boilers in order to maintain a similar amount of running time on each boiler. If set to Off, the firing sequence if fixed starting with boiler 1 to boiler 4. • Use the Fixed Lead / Off DIP switch to exclude the first boiler in the rotation sequence. This DIP is only active when the Rotate / Off DIP is set to Rotate.
Display Menus View Menu (1 of 2) The View menu items display the current operating temperatures and status information of the system. Item Field Range Access -76 to 149°F (-60.0 to 65.0°C) USER INST ADV -22 to 266°F (-30.0 to 130.0°C) USER INST ADV VIEW VIEW VIEW MENU VIEW ---, 35 to 230°F (---, 1.5 to 110.0°C) ADV ---, 35 to 230°F (---, 1.5 to 110.0°C) ADV -22 to 266°F (-30.0 to 130.0°C) USER INST ADV VIEW VIEW VIEW -22 to 266°F (-30.0 to 130.0°C) ADV VIEW 0 to 252°F (-18.0 to 122.
View Menu (2 of 2) Item Field Range Access hr 0 to 9999 hours ADV hr 0 to 9999 hours ADV hr 0 to 9999 hours ADV VIEW 2 VIEW MENU VIEW 3 VIEW 4 Description BOILER 2 RUNNING TIME SECTION C The total running time of Boiler 2 since this item was last cleared. To clear this item, press the Up and Down buttons simultaneously while viewing this item. Note: This item is only available when Boiler 2 is set to Auto.
Adjust Menu (1 of 6) The Adjust Menu items are the programmable settings used to operate the mechanical equipment. Item Field Range Access Description Actual Setting ADV MODE SECTION C Selects the control mode of operation. INST ADV ROOM OCCUPIED SECTION B The desired room air temperature during the occupied period. Note: This item is only available when DIP is set to Demands AND OUT DSGN is set between -60 to 45°F.
Adjust Menu (2 of 6) Item Field Range CP1, Au (Auto), OFF ADJUST 3 Default = Au CP1, Au (Auto), OFF ADJUST 3 Default = Au CP1, Au (Auto), OFF ADJUST Default = Au OFF, -60 to 45°F (OFF, -51 to 7.0°C) ADJUST MENU ADJUST Access Description INST ADV BOILER 2 SECTION C Selects Whether Boiler 2 is operational or not. CP1 copies the settings of boiler 1 to boiler 2. INST ADV BOILER 3 SECTION C Selects whether Boiler 3 is operational or not. CP1 copies the settings of boiler 1 to boiler 3.
Adjust Menu (3 of 6) Item Field Range Au (Auto), 2 to 42°F (Au, 1 to 23.5°C) ADJUST Access Description ADV BOILER DIFFERENTIAL SECTION C The temperature differential that the control is to use to cycle the boiler On and Off (half above and half below target). ADV BOILER STAGE MODE SECTION C Selects the firing sequence of the stages when using multi-stage boilers. Note: Only available in Mode 3. ADV RELAY SECTION D Selects the operation of the relay to be either combustion air or alert.
Adjust Menu (4 of 6) Item Field ADJUST Range Access Description Lo, Med, Hi INST ADV BOILER 1 MASS SECTION C The thermal mass characteristics of the boiler. Note: This item is only available when Boiler 1 is set to Au. ADV BOILER PUMP 1 PURGE SECTION H The time the boiler pump remains on once the boiler is turned off. Note: This item is only available when Boiler 1 = Au and Mode = 2, 4 or 5.
Adjust Menu (5 of 6) Item Field Range 1 to 42°F (0.5 to 23.5°C) ADJUST Default = 6°F (3.0°C) ADJUST Occ OFF, 100 to 220°F (38.0 to 104.5°C) Access Description ADV DHW DIFFERENTIAL SECTION E The temperature differential (swing up and down) of the DHW tank from the DHW setting. Note: This item is only available when DHW Mode is set to either 1, 2, 3, 4 or 6 AND the DHW Sensor is set to On, AND the Pump Sequencing DIP is set to Off. ADV Default = 180°F (82.
Adjust Menu (6 of 6) Item Field Range ADJUST OFF, On Default = On OFF, AUTO, 0:20 to 4:00 hours ADJUST Access Description ADV SECTION M ZONE LOAD SHEDDING Selects whether Zone Load Shedding is active or not. Note: This item is only available when a tN4 device is present and Boil Min is set between 80 to 180°F (26.5 to 82.0°C). ADV PRIORITY OVERRIDE SECTION E & F The amount of time priority is given for DHW or Setpoint operation before space heating resumes.
Time Menu (1 of 2) Note: The Setback / Off switch setting must be in the Setback position in order to have access to the TIME menu. The Time menu items set the time clock, day and date. Item Field Range TIME Default = MONDAY 12:00 AM AM TIME Access Description USER CURRENT TIME AND DAY SECTION J Displays the current time and day of the week. The time and date flash if the time is not set.
Time Menu (2 of 2) Item Field Range Access TIME MENU TIME Description YEAR Set the current year. SECTION J 2000 ... 2255 INST Default = 2005 ADV Note: This item is only available when Daylight Savings Time is set to Mode 1 or 2. 12 hr OR 24 hr INST Default = 12 hr ADV MODE SECTION J Select whether time should be displayed using a 12 or a 24 hour clock. TIME After the last item, the control returns to the first item in the menu.
Schedule Menu (2 of 3) Item Field SCHD Range AM Wake UnOcc Sleep – –:– – to 11:50 PM or – –:– – to 23:50 Wake Default = 6:00 AM UnOccupied Default = 8:00 AM Occupied Default = 6:00 PM Sleep Default = 10:00 PM SCHD AM Wake UnOcc Sleep – –:– – to 11:50 PM or – –:– – to 23:50 Access USER INST ADV USER SCHEDULE MENU INST Wake Default = 6:00 AM UnOccupied Default = 8:00 AM Occupied Default = 6:00 PM Sleep Default = 10:00 PM SCHD AM Wake UnOcc Sleep – –:– – to 11:50 PM or – –:– – to
Schedule Menu (3 of 3) Item Field SCHD Range AM Wake UnOcc Sleep Wake Default = 6:00 AM UnOccupied Default = 8:00 AM Occupied Default = 6:00 PM Sleep Default = 10:00 PM SCHD AM Wake UnOcc Sleep SCHEDULE MENU – –:– – to 11:50 PM or – –:– – to 23:50 – –:– – to 11:50 PM or – –:– – to 23:50 Wake Default = 6:00 AM UnOccupied Default = 8:00 AM Occupied Default = 6:00 PM Sleep Default = 10:00 PM SCHD AM Wake UnOcc Sleep – –:– – to 11:50 PM or – –:– – to 23:50 Wake Default = 6:00 AM Un
Misc (Miscellaneous) Menu (1 of 1) The Miscellaneous menu items set display and control options such as access level and temperature units. Item Field MISC Range Access USER, INST, ADV USER Default = INST ADV °F, °C MISC MENU MISC MISC Default = °F 1 to 24 OFF, SEL MISC Default = OFF INST USER INST ADV 274, Software Version ACCESS LEVEL PAGE 4 The access level of the control. The access column shows which items are visible in each access level.
Testing the Control Step 7 The control has a built-in test routine that tests the main control functions. The control continually monitors the sensors and displays an error message whenever a fault is found. The individual outputs and relays are tested using a test sequence. Test Sequence Each step in the test sequence lasts 10 seconds. • Start the test sequence by pressing the Test button. • Pause the test sequence by pressing the Test button again.
To Enable Zone Test: 1. Press and hold the Test button for more than 6 seconds. The control displays ZONE TEST OFF and the Test LED remains on. Press and Hold for 6 seconds Test 2. Press the Up button to change the display to ZONE TEST ON. After 3 seconds, the boiler and all pumps are shut off. 3. The control operates stage one of the tN4 device with the lowest address number. Device number one (b:01) has the lowest address number and device 24 (b:24) has the highest address number.
Error Messages (2 of 3) Error Message Description VIEW SCHEDULE MASTER ERROR More than one tN4 device has been assigned the same master number. BOILER SUPPLY SENSOR SHORT CIRCUIT Due to a short circuit, the control failed to read the boiler supply sensor. When there is a call for heat, the control no longer controls the boiler(s). Instead, the control provides a boiler enable to the boiler’s aquastat or boiler control until the sensor is repaired.
Error Messages (3 of 3) Error Message Description VIEW PRIMARY PUMP P1 & P2 FAILURE Both the primary pump P1 and P2 have failed. VIEW PRIMARY PUMP P1 FAILURE The primary pump P1 has failed. The Prim P1 relay closed, but a flow proof demand was not detected before the proof demand delay time elapsed. VIEW PRIMARY PUMP P2 FAILURE The primary pump P2 has failed. The Prim P2 relay closed, but a flow proof demand was not detected before the proof demand delay time elapsed.
Technical Data Boiler Control 274 One tN4, Four Stage Boiler & DHW / Setpoint Literature Control Dimensions Approvals Ambient conditions Power supply Relays Demands Sensors included: — — — — — — — — — — — 274_D, 274_A, D 001, D 070 Microprocessor control; This is not a safety (limit) control Enclosure A, blue modified PVC plastic 6-5/8” H x 7-9/16” W x 2-13/16” D (170 x 193 x 72 mm) Certified to CSA C22.
