Advances in electronics technology are making an exciting impact in our oil heat industry. These developments have enabled control manufacturers to put high performance features into residential primary controls. Residential controls are now being made available to you that have features that were previously found only with the expensive primary control units for commercial or industrial applications. Features like valve-on delay (pre-purge), burner motor-off delay (post-purge), and interrupted duty ignition are becoming universal. Preignition, limited reset, recycle, and alarms contacts are also helping to make today’s controls advanced and powerful tools.In this post, we'll discuss some of these important improvements and present a list of descriptive terms to help you become familiar with this new generation of controls.
Modern Primary Control Technical Developments
Over time, primary controls have continued to advance with the development of new features and technologies that make controls more safe, efficient, and reliable. Here are several of the modern features that have allowed for better and safer operation of the heating system:
- Relays have become smaller and more reliable. It is now common to see several relays inside each control, so that the motor, ignitor, and valve may all be controlled by separate relays. Solid state relays are increasingly being used instead of the traditional electromechanical relays.
- Microcontrollers (small computer chips designed specifically to control other electronics) have increased the ability to control the burner’s components separately and with more intelligence. A microcontroller’s software code can easily add control functions and make complex decisions, eliminating the need for large decision-making circuits. Circuits are now needed mostly to provide processor and 24 Volt power, convert sensor signals, and drive relays.
- Timers have developed from being controlled by bimetal switches to being controlled by semiconductors. Now, many different timers can all be running at the same time. Timings are less affected by temperature, vibration, light, line voltage, etc. They can be accurate to within fractions of a second, instead of varying by 10% to over 50% for some traditional controls.
- Flame sensing has progressed from stack mounted bimetal switches to cadmium sulfide sensors (cad cells) and ultraviolet sensors. These sensors can more quickly and accurately sense the flame, and they also have the ability to sense the varying brightness of a flame. Software programming can monitor the rise and fall of a cad cell resistance to better interpret its signal. For instance, the cad cell signal can be smoothed out to help prevent nuisance lockouts.
NOTE: For proper operation [of most oil burners], it is important that the cad cell resistance is below 1600 Ohms.
- Self checking and system checking to ensure a safe, proper starting and operation of the burner are now standard procedures in microcontroller-based controls.
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Advanced Features of Today's Newest Primary Controls
In addition to the general primary control developments that have provided benefits to the heating industry, several advanced features have also been added to primary controls in recent years that allow both technicians and consumers to better maintain and operate their high-performance heating systems.
For Beckett, the GeniSys™ line of primary controls have replaced the Honeywell R7184 series control and come equipped with these more advanced features in addition to the technological developments listed above.
- Welded relay protection with redundant motor relays ensure that no relays are welded closed, which would negate the safety protections of the cad cell sensors. Welded relay checking helps to ensure that the systems does not continue to run when the systems should be off.
- Pump priming mode provides the technician with four full minutes to ensure that all air has been purged from the line and ensures that oil is delivered to the burner without air bubbles for consistent performance. In the past, technicians would manually prime the pump, which left little time to ensure that no air bubbles existed in the line, creating a potential after drip that could lead to smoke, odors and interrupted delivery of oil. With the pump priming feature, these issues are eliminated.
- Advanced diagnostics allow the tech to see the history of the control's performance in order to assess how well it has been running. With this information easily accessible at hand, technicians can more easily pinpoint the cause of an issue and better resolve that issue. These diagnostics can give the technician a real-time look at burner performance as well, including what cycle it's on, run time, voltage, cad cell reading, and long-term quality of the flame. Diagnosis can be done through a display [for] the control before the burner is adjusted accordingly.
- Brown out protection measures the voltage of the system's microprocessor that controls all central function of the system to check for inconsistencies. While voltage inconsistencies could cause the microprocessor to send incorrect signals that interrupt the proper operation of the burner, potentially shutting the system off unnecessarily or interrupting the recognition of the cad cell, brown out protection causes the system to shift into standby mode when the electric current is not right for operation.
- LED indicators offer an increasing amount of diagnostic information such as recycling, flame status, or different lockout modes. Indicators like these are making it easier than ever to know what was happening before you arrived at the installation. Color-coded LEDS on the outside of the primary control always help consumers recognize control operation using a quick visual signal.
- Recycle mode provides a backup alternative for the system when the flame is lost after a successful trial for ignition. Instead of shutting the entire system down, recycle mode allows the control to wait one minute after a burner shut down to allow gas to stabilize before attempting to start up the system again automatically. Recycle modes are limited to ensure safety.
- Alarm contacts close in the event that the burner locks out and immediately sends a signal to remotely indicate the burner is off on safety. This signal can be sent to an alarm company to alert customers of the potential need for service. When customers are aware of the operation of their burner, they can make necessary arrangements for service before their loss of heat becomes a bigger issue, especially in colder temperatures.
As primary control technologies continue to develop and new accessories are produced to solve heating and control issues, modern controls will also continue to become more efficient and safer to use in the future.