In my previous post, I talked about how many facility managers do not perform a detailed review of their building control valves and actuators, despite the critical role these devices play in HVAC and building management systems (BMS). By overlooking these devices, facility managers simply don’t know when something is wrong, and therefore don’t realize how much money they’re wasting.
In this post, I walk through six common problems that affect valve and actuator performance, and then I discuss a tool that helps facility managers prevent them.
These problems occur in both valves and actuators themselves as well as in the building control systems that regulate them. They cause energy waste, unnecessary equipment wear, poor occupant comfort, and other costly headaches.
Six energy-wasting valve and actuator problems
- Damage to valve internals and seals: Debris, excessive chemicals, and foreign matter can foul up your devices. While a leaky seal may not sound like a big deal, it can create situations such as simultaneous heating and cooling. These issues are hard to detect because the system achieves desired temperature, but over time they can waste tens of thousands in energy costs.
- Control loop hunting: Incorrectly set proportional-integral-derivative (PID) control loop parameters are hard to spot, but they can create a large amount of energy waste. Why? When heating and cooling valves overshoot set points, they can cycle from closed to 100 per cent open over and over again (hunting) to hit that set point, which is extremely inefficient.
- Electrical noise in the control signal: A poor wiring job creates interference and impairs communication between valves and other systems. This issue can lead to premature equipment failure and energy waste.
- Incorrect valve sizing and sensor-to-room pairing: During installation, sometimes the wrong size of valve can be selected or calibrate the sensor poorly. Over time these inconspicuous errors lead to major waste.
- Too much pressure at valve inlets: When there is too much pressure at the valve inlet for example due to other valve positions affecting pressure, flow rates and pressure drops change from the initial design resulting in impaired valve operation and energy efficiency.
- Seasonal temperature changes: As seasons change, the system set points and control parameters should be tuned to the new conditions, as part of this control loops PID settings and valve and actuators should be re-calibrated to maximize energy efficiency.
Embracing your inner ‘controls freak’
You may have noticed a trend in this list: Many of these issues are hard to detect. To make matters more difficult, add in the hundreds or thousands of valves and actuators in your building. All this complexity coupled with a lack of visibility explains why 55 per cent of facility managers in the US still rely on a reactive, ‘put out the fires’ maintenance approach. In essence, the only way they can tell something is wrong is when it breaks.
But the technology is changing, and it’s allowing facility managers to embrace their inner controls freak. As BMS tools become more robust, many facility managers can use predictive analytics to monitor individual valves, actuators, and other equipment in ways that humans alone simply can’t afford to do.
With predictive analytics tools, your BMS proactively alerts you to these six problems before they bring down your bottom line — or your HVAC system. These tools can spot leaky valves, control loop hunting, control signal noise, and much more. Once they spot the problem, they also provide actionable data on how to fix it.
Worried about your valves? Wondering how predictive analytics works? Let me know in the comments. And be sure to check out our new white paper on maintaining high-performance valves and actuators.
7 years ago
This blog is very helpful! Thanks for your ideas!
6 years ago
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