Configuring your boiler blowdown controller correctly is essential for protecting your boiler, minimizing energy loss, and maintaining water quality. In this post, we walk through the controller settings specific to boiler blowdown across Lakewood’s lineup, including sample methods, timer intervals, and the ball valve delay setting for motorized blowdown valves.
Lakewood has two dedicated boiler controllers, the Model 150 and Boiler NexSys. We also have two controllers (Models 1575e and 3175) that can be used for cooling tower applications as well as boilers. Let’s talk about the controller settings that are specific to boiler blowdown.
Boiler Blowdown Methods and Timers
All four of the controllers mentioned above can perform “Continuous” and “Sample/Cycle” boiler blowdown methods.
The Model 150 and Boiler NexSys have the additional method option of “Sample/Hold.”
Check out a detailed description of the boiler sample methods here.
It is very important to have appropriate timers when using “Sample/Cycle” or “Sample/Hold” sample methods. The correct intervals depend on the specific system. Please note the sample time is entered in minutes and seconds (MM:SS) while the cycle time is entered in hours and minutes (HH:MM). The hold time on the Model 150 and Boiler NexSys is set at 45 seconds.
As the name implies, there are no timers associated with the “Continuous” sample method.
Ball Valve Delay Setting for Motorized Boiler Blowdown Valves
Understanding the difference between cooling tower and boiler blowdown valves is key to configuring this setting correctly. Cooling tower blowdown valves typically require power to open and close automatically when power is removed by means of a spring or on-board capacitor. Note that there is only one power connection along with the neutral.
In contrast, boiler blowdown systems use motorized ball valves, which require power to open and power to close. There are separate power connections to the valve actuator for each.
It takes a certain amount of time for the valve to “stroke” fully from one position to the other. If the valve is commanded to close before it completes the process of opening, or vice-versa, it will end up in a half-open state. The ball valve delay feature prevents this from occurring.
How to set your Ball Valve Delay:
- Time how long the valve takes to fully open.
- Time how long the valve takes to fully close.
- Take the longer of the two values and add 1 second.
- Enter that value as your BALL VALVE DELAY.
This delay time will also be observed when manually operating the blowdown relay.
Frequently Asked Questions
What is the difference between continuous and sample/cycle boiler blowdown?
Continuous blowdown keeps a small flow of water constantly moving across the conductivity probe and opens the motorized ball valve when conductivity exceeds the setpoint. Sample/cycle blowdown checks conductivity periodically, at user-defined intervals, and triggers blowdown only when needed. Continuous is typically used on larger boilers; sample/cycle is more common on smaller systems.
What is sample/hold boiler blowdown?
Sample/hold is a method available on the Lakewood Model 150 and Boiler NexSys controllers. It is designed for boilers prone to steam flashing, which causes erratic conductivity readings. A Hold Time (45 seconds) is built in to allow the sample to stabilize before a reading is taken, ensuring accurate blowdown control.
What is ball valve delay on a boiler blowdown controller?
Ball valve delay is a setting that prevents a motorized ball valve from being commanded to reverse direction before it has finished stroking fully open or closed. Without this delay, the valve could end up stuck in a half-open position. To set it, measure the full stroke time in both directions, take the longer value, and add one second.
Have questions about configuring your Lakewood boiler blowdown controller? Contact us today to learn more.