- Data Brochure D 279 05/10 Steam Control 279 The tekmar Steam Control 279 can operate a single on-off steam boiler or an on-off steam valve using outdoor reset. The control determines the on time of the boiler or valve based on the measured outdoor temperature and settings entered by the installer. A large LCD displays the current status and operating temperatures.
How to Use the Data Brochure This brochure is organized into four main sections. They are: 1) Sequence of Operation, 2) Installation, 3) Control Settings, and 4) Testing and Troubleshooting. The Sequence of Operation section has fourteen sub-sections. We recommend reading ‘Section A: General’ of the Sequence of Operation, as this contains important information on the overall operation of the control. Then read the sub sections that apply to your installation.
Display Menu Field Number Field Status Field Displays the current value of the selected item Displays the current status of the control’s inputs, outputs and operation Displays the current menu STATUS Establishing Steam Heat Cycle Item Field Lockout Differential Displays the current item selected. DHW Tankless Coil Heating Buttons Selects Menus, Items and adjusts settings Menu Item Symbol Description °F°C POINTER Displays the control operation as indicated by the text.
Definitions The following defined terms and symbols are used throughout this manual to bring attention to the presence of hazards of various risk levels, or to important information concerning the life of the product. Caution: Refer to accompanying documents. Sequence of Operation General Section A Powering up the control Status When the control is powered on, all segments in the LCD are turned on for 2 seconds. Next, the control displays the control type number in the LCD for 2 seconds.
The Adjust menu includes a Steam Established setting that delays the start of the heating cycle until the condensate sensor has reached a set temperature. One method to set the Steam Established setting requires two people with two-way radios. One person is at the control location; the other person is at the furthest radiator location. The steam system can be manually started using the Max Heat feature.
Outdoor reset is a method of operating a heating system based on the fact that the rate at which a building loses heat to the outdoor environment is mostly dependent on the surrounding outdoor air temperature. As the outdoor temperature gets colder, the heat loss of the building increases at a proportional rate. This relationship between heat loss and colder outdoor temperatures is called a heating curve.
Heating Cycle - Cycle Length Section D The control is designed to operate on/off steam boilers or steam valves. These systems can only produce heat at a fixed rate (on = 100%, off = 0%). In order to match the heat loss of the building, the steam heating system must be cycled on and off. To determine the boiler on time, the control uses the percent on time required by the heating curve and multiplies this by the heating cycle time.
Optional Indoor Sensors Section F Multiple indoor sensors can be added to improve the temperature accuracy within the building. Available indoor sensors include the 076, 077 and 084. Should additional indoor sensors be desired, a square number (4, 9, 16, etc.) of sensors can be wired in seriesparallel to a single indoor sensor input. To Indoor Sensor Input Series - Parallel Wiring Indoor Sensors 084, 077 and 076 The control allows two indoor sensors to be directly connected to the control.
Optimum Start Section J The control includes an optimum start feature that is available in the Adjust menu when indoor sensors are installed and the Setback / Off switch setting is set to Setback. The optimum start can be set to either on or off. When a programmable schedule is used to lower the building temperature at night, there is a time delay to increase the building temperature from the Unoccupied to the Occupied temperature.
Domestic Hot Water Tankless Coil Section N The control can replace the mechanical aquastat in the steam boiler that operates a tankless coil domestic hot water system with an optional DHW Tankless Coil Sensor. The sensor is installed into the 1/2” (12 mm) immersion well that measures the temperature of the tankless coil. Universal Sensor The advantage of using the DHW Tankless Coil feature is that the control can be programmed to operate the tankless coil on a night setback schedule.
Step Three — Rough-in Wiring All electrical wiring terminates in the control base wiring chamber. The base has standard 7/8” (22 mm) knockouts, which accept common wiring hardware and conduit fittings. Before removing the knockouts, check the wiring diagram and select those sections of the chamber with common voltages. Do not allow the wiring to cross between sections as the wires will interfere with safety dividers which should be installed at a later time.
Boiler The Boiler terminals (7 and 8) are isolated outputs in the control. There is no power available on these terminals from the control. These terminals are to be used as a switch to either make or break the thermostat input on a steam boiler or the power to a steam valve. Since this is an isolated contact, it may switch a voltage between 24 V (ac) and 230 V (ac).
Step Five — Testing the Wiring General Each terminal block must be unplugged from its header on the control before power is applied for testing. To remove the terminal block, pull straight down from the control. A good quality electrical test meter, capable of reading from at least 0 – 300 V (ac) and at least 0 – 2,000,000 Ohms, is essential to properly test the wiring and sensors.
Boiler If a steam boiler or steam valve is connected to the Boiler terminals (7 and 8), make sure power to the boiler circuit is off and install a jumper between the terminals. When the circuit is powered up, the boiler should fire or the steam valve should open. If the boiler or steam valve does not turn on, refer to any installation or troubleshooting information supplied with the boiler or steam valve. If the boiler or steam valve operates properly, disconnect the power and remove the jumper.
Switch Settings GENERAL The switch settings on the control are very important and should be set to the appropriate settings prior to making any adjustments to the control through the User Interface. The switch settings change the items that are available to be viewed and/or adjusted in the User Interface. If a switch setting is changed while the control is powered up, the control responds to the change in setting by returning the display to the VIEW menu.
Display Menus View Menu (1 of 1) The View menu items display the current operating temperatures and status information of the system. Item Field Range Access Description -76 to 149°F (-60.0 to 65.0°C) User OUTDOOR SECTION C Current outdoor air temperature as measured by the outdoor sensor. User ROOM 1 SECTION F Current room air temperature as measured by indoor sensor 1. Available when: • Indoor Sensor S1/Off switch setting is set to S1.
Adjust Menu (1 of 3) The Adjust Menu items are the programmable settings used to operate the mechanical equipment. Item Field Range 35 to 100°F (1.5 to 38.0°C) Default = 70°F (21.0°C) 35 to 100°F (1.5 to 38.0°C) Default = 65°F (18.5°C) OFF, On ADJUST MENU Default = OFF OFF, 0:20 to 8:00 hr Access Description User SECTION F ROOM OCCUPIED Select the desired room temperature of the building during the occupied period.
Adjust Menu (2 of 3) Item Field Range 35 to 100°F (1.5 to 38.0°C) Default = 70°F (21.0°C) Auto, 20 to 100 min Access Description Installer INDOOR DESIGN SECTION C Select the design indoor air temperature used in the heat loss calculations. Typically set to the desired indoor temperature. Installer CYCLE SECTION D Select the length of the heating cycle in minutes. Auto setting is only available when indoor sensors are present.
Adjust Menu (3 of 3) Item Field Range 35 to 100°F (1.5 to 38.0°C) ADJUST MENU Default = 65°F (18.5°C) 35 to 100°F (1.5 to 38.0°C) Default = 60°F (15.5°C) °F or °C Default = °F Access Description Actual Setting User WARM WEATHER SHUT DOWN OCCUPIED SECTION I Select the steam system’s warm weather shut down temperature during the occupied period. WWSD does not affect DHW Tankless Coil operation.
Schedule Menu Note: The Setback/Off switch setting must be in the Setback position in order to have access to the SCHEDULE menu. Setting the Schedule A schedule allows the control to automatically change between the Occupied and Unoccupied temperature settings based on the time of day. A two-event schedule divides the day into Occupied and Unoccupied time periods. A four-event schedule divides the day into Occupied 1, Unoccupied 1, Occupied 2, and Unoccupied 2 time periods.
Test Sequence Step 1 Turn on the Boiler relay for 10 seconds, then shut off. Each step in the test sequence lasts 10 seconds. During the test routine, the test sequence may be paused by pressing the Test button. If the Test button is not pressed again for 5 minutes while the test sequence is paused, the control exits the entire test routine. If the test sequence is paused, the Test button can be pressed again to advance to the next step. This can also be used to rapidly advance through the test sequence.
Document the Control Isolate the Problem Document the control for future reference. Before making any adjustments to the control, note down all of the items that the control is currently displaying. This includes items such as error messages, current temperatures and settings, and which devices should be operating as indicated by the LCD. This information is an essential step if additional assistance is required to diagnose the problem. Isolate the problem between the control and the system.
Error Messages (2 of 2) ROOM 1 SHORT CIRCUIT The room 1 short circuit error message causes the Alert 2 Low relay to turn on. The control is no longer able to read the indoor sensor 1 due to a short circuit. In this case the control will continue operation using indoor sensor 2. If indoor sensor 2 is not available, then the control operates without using indoor temperature feedback. Locate and repair the problem as described in the Data Brochure D 076, D 077, or D 084.
Technical Data Steam Control Control 279 One Stage Literature Control Packaged weight Dimensions Approvals Ambient conditions Power supply Relays Sensors included: Optional Devices — — — — — — — — — — — — D 279, A 279, D 001, D 070 Microprocessor control; This is not a safety (limit) control 3.3 lb.
