Energy is wasted when coils do not operate efficiently. Achieving the ideal amount of heat transfer in a given coil is critical for overall system efficiency. When this does not occur, pumps, chillers and boilers must work harder to maintain space setpoints, a scenario that creates substantial energy waste. This is especially problematic in large chilled water systems because it frequently results in low Delta T – meaning that return water temperatures to the chiller are lower than the designer intended which undermines chiller plant efficiency.
Many of these problems can only be addressed at the coil. Recently published; A Field Study by Gregor P. Henze, Department of Civil, Environmental and Architectural Engineering of University of Colorado Boulder and Walter Henry, Massachusetts Institute of Technology, Cambridge, MA and Marc Thuillard from Belimo Automation AG on Improving Campus Chilled Water Systems with Intelligent Control Valves.
The abstract of the field study states: “The degradation of the temperature difference between supply and return flow, known as ΔΤ degradation, in chilled water systems has been widely observed and documented over the last 25 years. High pumping energy consumption as well as reduced efficiency of the chillers operating under part-load conditions, lead to a decrease of overall system efficiency of chilled water plants. This article describes a field study conducted on two university campuses in Massachusetts and Colorado during the cooling season of 2011. The purpose of this experimental study was to alleviate ΔΤ degradation problems on both campuses through the use of intelligent pressure-independent control valves, and to quantify the improvements achieved. The MA field results revealed that the intelligent control valves when coupled with a ΔΤ management strategy have allowed the campus to serve additional cooling load on its campus with the same distribution and central plant system.”1
1 AEI 2013 © ASCE
In HVAC plants, water distribution can be accomplished at constant or variable flow. Each type of distribution system has advantages and disadvantages. Today variable flow systems using electronic 2-way control valves became generally accepted as the industry standard due to their benefits. The main reason for becoming the industry standard is reduced pumping cost, which is a result of pump head and flow. Meaning, the more control valves are closing, the lower the total flow. Another reason is that the plant can be designed with a diversity factor because flow is only needed where energy is demanded. Besides these advantages there are disadvantages in today’s variable flow systems.
Disadvantages of Today’s Systems:
Time Consuming Balancing
According to its flow design each control valve requires a balancing valve to adjust the hydronic circuit. The balancing procedure dictates the quality of the system and requires highly skilled technicians and tools. During the balancing all control valves must be in their open position. However, as soon as the system is running, depending on different cooling or heating load requirements in the building, valves are permanently closing and opening which results in a dynamic system pressure. Balancing variable flow systems is time consuming and can be conducted only under “static” design conditions.
In a conventional system, if terminals are added the whole system needs to be rebalanced because some existing terminals must be throttled back.
Or imagine a 10-story-building where every 2 months one floor is being remodeled in which balancing of the whole system is required after finishing each floor. Of course this applies also to buildings with changing tenants or new utilization of spaces.
Poor Valve Authority
Only 1% of the time is a building typically running under design conditions. The other 99% the hydronic system needs to provide an average load of 50%. Thus flow is reduced to 20% and differential pressures across control valves increase. Since the CV-rating of the valve was sized for design conditions, the valve authority decreases and the modulating valve is downgraded to one acting open or close only. This makes hunting expected.
Potential Spreading of Control Problems
Control circuits are interactive. Therefore when one control valve closes, the differential pressure on other circuits increase and the associated control valves must close to compensate. So when one or more loops are instable, control problems can spread to other control valves.
If flow is higher than required, ΔT will decrease and result in a cooling plant with lower return temperatures to the chiller and reduce the efficiency. If a chiller cannot run at peak efficiency it is more likely that the next chiller in a series will be forced to start sooner than required causing additional electricity and maintenance costs.
The opposite happens in a condensing boiler where a higher return temperature can avoid the condensing process when the dew point of the exhaust gases cannot be achieved.
The same phenomenon can happen in coils. In a heating coil for instance, overflow will result in a lower ΔT and decrease the coil’s performance which can result in discomfort due too a low room temperature.
The Pressure Independent Characterized Control Valve (PICCV), is based on the proven Characterized Control Valve, CCV, technology. In many tests and surveys the CCV has outperformed globe valves due to a true equal-percentage valve characteristic and higher close-off ratings.
In a PICCV the CCV is combined with a differential pressure regulator. This regulator maintains a constant flow passing through the valve regardless of pressure variations in the system. The flow is held constant, but independent on the degree of ball opening. This is the most important at part-load; for instance when a PICCV with a nominal flow of 10 GPM operates at 3 GPM, a flow of 3 GPM is maintained.
The PICCV is available in the flow range from 0.5 to 60 GPM (1/2” to 2”) and a pressure operating range from 0 to 50 PSI.
Advantages of the PICCV:
There is no CV calculation required and after the flow calculation the appropriate valve can be selected. If the flow is 8.7 GPM the correct selection is a 9.0 GPM valve. Generally the next bigger valve should be selected. However, an adjustment in the field is always possible considering the adjustable flow range.
Hydronic Balancing Simplified.
Pressure Independent Control Valves make circuits independent and they literally decouple circuits or terminals from the system. There is no balancing procedure required and for commissioning, a simple check of ΔT or flow is enough.
To measure flow, PICCVs are available with pressure ports to gage pressure differential. A valve specific chart may then be used to locate the matching flow from the gage pressure differential.
Plants can be commissioned in a step-by-step approach. Individual zones can be setup and no rebalancing is required which simplifies adding to the system or remodeling.
One Piece Installation
The compact pressure independent valve incorporates the control valve and the balancing valve. Thus, the valve saves 50% of labor costs during installation and investment for the balancing valve. Additionally about 2/3 of the installation space (pipe length) is saved.
Reduces Pumping Costs
The PICCV assures that each terminal, depending on its load, obtains the required flow and that overflow can be prevented. Therefore, the total flow will be lower than in systems without pressure independent valves. The pump head follows a similar behavior and thanks to the automatic dynamic balancing the required pump head is substantial lower. The maximum required pressure across a PICCV is 3 to 5 PSI, compared to a control valve and a balancing valve where the minimum pressure drop with the balancing valve fully open is approximately 5 PSI (4 PSI control valve, 1 PSI balancing valve). However, depending on the systems dynamic as soon as the balancing valve is throttled back the pressure drop for instance may increase up to 20 PSI.
Pressure independent valves are ensured to have the designed flow for full or part load situations. Therefore, the calculated ΔT will be accomplished which will then lead to higher efficiency of chillers, condensing boilers, coils or heat exchangers.
In a VAV-plant the flow can be shown on the control system’s display due to the feedback signal of the actuator being interpreted to actual flow and in combination with
supply and return temperatures even the actual energy consumption is available. The control system’s display allows faster system diagnosis for the building manager.
Prevents Overflow or Underflow
At morning start-up in a plant most control valves will drive fully open. In a conventional plant overflows have been experienced and less favored terminals do not receive enough flow, which increases the time by which all rooms achieve their setpoint.
With the PICCV, each terminal is receiving a proportional flow and the start-up procedure is parallel. The PICCV can save up to 2 hours of start-up time every day and can reduce energy costs by 4 to 6% in a cooling plant.
In summary, all of these benefits create different values to the involved parties while building a new HVAC-plant or retrofitting.
The PICCV offers new applications and possibilities for the HVAC-Planner. For the first time in the history of HVAC-systems it is possible to design a plant that is following the calculated flow rates in reality. Above all, valve sizing became drastically simplified.
For the mechanical contractor the PICCV reduces installation time and accelerates the commissioning of the system. In existing plants where pressure drop calculations are unknown the PICCV is almost the only way to ensure proper function and stable control.
Because the PICCV is absorbing all pressure changes in the system the control loop is stable and a risk for hunting is eliminated. The designed room temperatures are more likely to be achieved from the start and less hassle with the hydronic system is guaranteed.
Thanks to the high standard the PICCV is setting for the performance of hydronic systems, the importance of a well- balanced system is emphasized. The new valve frees up time to focus on other parts of the plant and delivers the foundation to a precise balancing of the airside.
A system with PICCVs offers better comfort and less maintenance costs. The system is saving energy costs by reducing the power consumption of pumps and decreasing cooling or heating supply.
Depending on the design of the plant, investment costs will be lower because the balancing valve is not required and other system components can be smaller sized.
By using bigger sizes of pressure independent valves above 100 GPM, investment costs can be higher compared to conventional valves but energy cost savings are substantial and pay-back time is typically below 2 years.
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A damper restricts airflow by obstructing the duct. Some multi bladed dampers have flanged frames to which ductwork is butted, and the open area is restricted only by blades and hardware. Most dampers in the U.S. are inserted into a sleeve, duct, or wall, and the frame obstructs part of the open area. The maximum free area for this type is about 80% for 48 x 36 in. (1200 x 900 mm) and larger-size dampers, and the minimum is about 40% for an 8 x 8 in. (200 x 200 mm) damper. The frame takes up most of the reduced space. The free area changes slightly with comer braces, linkage in airstream versus frame, airfoil versus triple V, and with type of frame. In round dampers, the blade is the only significant restriction.
Commercial flanged dampers of the type more commonly used in Europe may have 90% free area, and U.S. insulated blade and industrial dampers may have a maximum of only 70%. Check specifications in all cases. The information in this article is specific to U.S. hat-frame commercial dampers.
Figure above shows the two basic types of control dampers: parallel blade (PB) and opposed blade (OB). Sometimes, PB dampers are called single acting and OB dampers are called double acting in reference to the linkages. "The linkages from blade to blade can be located on the blades themselves but are more commonly located on one side within the frame. (Refer to the damper manufacturers' product reference manuals for construction details.) Figures below show the various details of dampers that affect flow and pressure losses.
In some dampers, not all the blades are the same height. A 24 in. (600 mm) high damper has slightly different size blades than one that is 22 in. (560 mm). Usually, one blade is larger than the others. On most blades, the damper shaft is mounted in the middle. Some are unbalanced, with the shaft located at about two-thirds position or at the end. Differences in flow characteristics result from these blade differences.
Blade seals can extend beyond the blade and affect the flow, particularly during the initial15° of opening. Different methods of sealing cause differences in flow characteristics. High-quality dampers have better linkages, and repeatability is easier to obtain. The Air Movement and Control Association International (AMCA) certifies airflow pressure loss testing.
Motors, linkages, and jackshafts that block a damper opening affect flow. Many installation practices affect the predicted response of a damper. Figure above shows the difference in flow profiles coming off PB and OB dampers. PB dampers cause air to tum direction during most of their rotation. Airstreams tend to reconnect easily after separation by the blades. The pressure drop through the wide-open damper is a function of free-area ratio. The pressure drop as the blades modulate is more a function of the turning during the first 60° of blade rotation.
OB dampers change the free area quickly during rotation, and turning only occurs at blades not opposed by another airstream. A vena contract forms between opposing blades, and turbulence is high.
There is little experimental data available about the details of airflow around and inside dampers. Thick-walled orifices and airstream obstruction data are the main sources of theoretical data. Testing data from manufacturers is the main source of hard data. Since testing is so expensive, and purchases tend to go to the lowest-cost vendor, most manufacturers provide only basic information in their data sheets, and the effects of various irregular flow profiles have yet to be studied.
This article is based on an excerpt from the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. book “Dampers and Airflow Control” by Laurence G. Felker and Travis L. Felker. You can purchase online at www.ashrea.org.
Belimo enhances SelectPro, their sizing and selection software tool. It includes many new user features, such as:
- Ability to change units from imperial to metric.
- Layout changes to enable other language support in the future.
- Manual Selection drop down allow you to directly select a valve to quick check pricing.
- Export Builder allowing you to export to Excel entire family of products and you can configure your export to specific criteria.
- New products have been added: New Generation Globe Valves, Jackshaft Linkage, and the Energy Valves (located with Pressure Independent Valves). (The 6-way valve will be available in a future release.)
The new version of SelectPro (V2.0.101) is now available online or offline. Try it out today; for additional information visit www.belimo.us.
Belimo New Generation Linear Globe Valve Actuators and Retrofit Linkages offer greater power and flexibility. Engineered to suit a broad range of HVAC applications, both the New Generation Actuators and Retrofit Linkages are highly adaptable making selection, installation, and long-term service worry-free. New force ranges is from 112 lbf [500N] to 1011 lbf [4500N] and there is a broader travel range from 0.6" (15 mm) to 2" (50 mm).
The NV/UNV series for globe valves and retrofit combinations have been phased-out on April 1st, 2013. Effective April 1st, 2013, the NV actuators and UNV linkages will no longer be available.
UNV/NV Verses New Generation Globe Valve Actuators and Linkages
The Belimo PC-Tool is a universal software application for setting, commissioning, monitoring and evaluating communications with Belimo actuators. Actuators are normally delivered with the basic settings. They can be individually programmed using the PC-Tool and precisely adjusted to the requirements of the system. Service related diagnostics for the actuators are extremely easy with the PC-Tool. Setpoints can be specified and actual values monitored. The trend recording function can output the information in a graphical format for system documentation.
In short, Belimo PC-Tool software is a graphical user interface which allows the user to set, modify and read actuator characteristics.
The Belimo PC-Tool is an MFT support tool which is a practical solution for Controls Distributors and Installation Contractors.
Controls Distributor can:
• Reduce inventory levels
• Optimize the flexible MFT product inventory
• Quickly program an MFT actuator
• Provide MFT custom retrofit solutions – same day
• Re-label the actuator with correct parameters
Installation Contractor or Field Technician can:
• Work with PCs having a dedicated hand held tool
• Connect and program actuators quickly on an as needed basis
• Get systems up and running faster for service replacement applications
• Optimize flexibility of MFT product inventory for replacement applications
Multi-Function Technology is offered only from Belimo which allows you to create custom solutions for individual applications, using the same programmable actuator. Whether you need a particular control or feedback signal, or need to change running speeds, MFT is the answer. It comes standard as a 2 to 10 VDC proportional control but can be reprogrammed on-site. You can modify voltage control, time proportional control, floating point, on/off and feedback signals too. In addition, MFT makes it easy to set parameters for running time, mechanical working range, address, status and diagnostics. Think of it as your all-in-one, Swiss army knife for HVAC.
Airside economizing shouldn’t just be good in theory.
It should deliver what owners expect. With the ZIP Economizer, it does. Airside economizing isn’t just a great way to reduce operating costs; it is a requirement in most non-residential HVAC systems throughout the United States. Airside economizers also fulfill another important requirement for buildings by providing the correct ratio of outside air and return air to deliver proper indoor air quality (IAQ) to meet codes.
Unfortunately, having an economizer system doesn’t necessarily mean you are accomplishing these goals. Studies* have shown that up to 70% of economizers are not functioning properly. Many times economizer systems are set up incorrectly or are simply left to operate in factory default mode. Even worse, because economizer failures generally do not result in comfort problems many failures go undetected! These problems persist, year after year, costing building owners unnecessary expense.** Meanwhile, energy standards and building IAQ requirements are not being met.
Why does this happen? Because most economizers incorporate factory settings and confusing manuals that makes setting up, operating, and troubleshooting difficult.
Until now, economizing solutions have left a lot of room for error. The new ZIP Economizer offered by BELIMO gets efficiency strategies back on track with easy setup, automatic code change over temperatures, and superior troubleshooting capability. Users know instantly when failures occur and the ZIP helps them quickly pinpoint the problem and address it. With the following features, the ZIP leaves nothing to chance:
Easy-to-read Automotive Grade LCD Display: Extremely simple to navigate, this display delivers clear live status information, easy setup, changes, and operating history.
ZIP Code Patented Technology: By simply entering your US zip code, or Canadian postal code, the system will automatically recognize your climate zone and will set the high limit change over temperature providing automatic compliance.
Plug and Play: With its self-configuration, if it’s not plugged into the economizer, you won’t have to worry about setting it up.
Acceptance Tests: Integrated onboard test sequence that ensures effortless compliance with California Title 24, and verification of proper operation.
Fault Detection and Diagnostics (FDD): Troubleshoot faults, initiates alarms, and reconfigures for best operation.
Onboard Information: First and only economizer control that integrates onboard help for setup or troubleshooting.
Modular Design: Flexible design capable of adding remote communication and or energy savings strategies on the same footprint.
It is an established fact airside economizing (using outdoor air as a cooling medium when conditions are suitable) is one of the smartest ways for buildings to save energy. But setting up controls to match the specific climate profiles and code requirements of different regions usually involves a cumbersome set of tasks.
The ZIP Economizer makes it easy. With an already built in all the relevant climate zone and energy code data, so simply by entering in your ZIP code you automatically maximize energy savings for your location! The ZIP code entry also automatically sets up economizer operation for compliance with all of the following codes and standards. You don't need to look up a thing!
- ASHRAE 90.1 - Energy Standard for Buildings Except Low-Rise Residential Buildings
- IECC – International Energy Conservation Code
- California Title 24 – California Building Energy Efficiency Standard
- NECB – National Energy Code of Canada for Buildings
The ZIP Economizer succeeds where others fail because it fully integrates economizing experience with local codes. Take Advantage of Utility Rebates. Not only does the ZIP ensure a maximum return on airside economizing. Many utilities will also help pay to install them. Visit www.ZIPeconomizer.com to learn more about rebate programs and energy savings opportunities.
*The Consortium for Energy Efficiency documented in 2002, that approximately 75% of rooftop units suffer from economizer malfunction, which resulted in energy use higher than without an economizer. An independent researcher in 2002, found that 70% of rooftop units in California had broken economizers (Jacobs 2002).
**The California Energy Commission reported that 64% of economizers had problems, ranging from low changeover temperature set point to failed sensors. A New Building Institute report indicates that up to 40% in energy savings can be achieved with repairing an economizer.
The pressure loss through any damper is a function of the entering flow profile, the free area ratio, F, of the open damper area to that of the damper frame or wall area, the geometry of the damper installation, and the exit conditions as air leaves the damper. The most complete testing of dampers was performed for ASHRAE’s Research Project 1157. A complete analysis of the results is available in the book Dampers and Airflow Control published by ASHRAE Special Publications. Not only the full open losses, but also the modulating characteristics of dampers are experimentally defined.
The method for getting accurate prediction of damper pressure loss is too extensive to repeat here, but using several Tables found in the book, very accurate results can be obtained.
In general, DP = Co Pv , that is the pressure drop is equal to a loss coefficient times the velocity pressure.
The trick is obtaining the right Co based on the other conditions by applying engineering judgment.
Co = Fg x f(F2) where Fg is a factor based on flow profile and F is the free area ratio. The function depends on the AMCA defined geometry.
Below a typical drawing from the Damper and Airflow Control book is reproduced.
Engineered Damper Assembly
Dampers and Airflow Control, Laurence G. Felker and Travis L. Felker, ISBN 978-1-933742-53-3 ©2009 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 1791 Tullie Circle, NE, Atlanta, GA 30329 www.ashrae.org
 AMCA Air Movement and Control Association, 30 West University Drive, Arlington Heights, IL 60004 www.amca.org
New Generation Globe Valve Actuators and Retrofit Linkages Offer Greater Power and Flexibility.
No two applications are exactly alike; new or old, they all vary in their demands. Whether it’s high pressure steam or difficult installations, New Generation Globe Valve Actuators are designed to adapt to these challenges offering easy installation and field adjustability. They can be adapted to most globe valves, regardless of make.
The New Generation Globe Valve Actuators incorporate not only strength, but flexibility too. Engineered to suit a broad range of HVAC applications, the new actuators and retrofit linkages are highly adaptable making selection, installation and service hassle-free.
- Travel ranges of up to 2" (50mm).
- Multiple voltage options (24V and 120-230V).
- One universal linkage can retrofit most globe valves, regardless of make.
- Increased force ranges for higher close-off pressures.
- Field selectable fail-safe position switches.
- Lower power consumption during operation.
- Easy selection process, minimized inventory.
As a leading manufacturer of electronic direct-coupled actuators and motorized valves, Belimo is committed to help improve comfort, safety and efficiency in buildings. Our new generation actuators and retrofit linkages provide increased force and constant speed to withstand high-pressure applications. The linear stroke operation ensures that consistent ambient temperatures are maintained in heating and cooling systems.
The New Generation Globe Valve Actuator has the “extra muscle” needed for applications where higher close-off pressures are required. Available on globe valves or with a retrofit linkage, these new actuators offer greater force up to 1011 lbf. The actuators are designed to withstand the rigorous demands of many HVAC applications.
With its innovative valve clamp and quick connect coupler, the New Generation Globe Valve Actuator can be installed and adapted in minutes.
February 19th - Retrofit Linkages with New Generation Actuators
April 1 - New Generation Globe Valve Actuator Assemblies
Head to AHR and see the latest innovative products being introduced to the U.S. market. With over 300 international exhibitors from 33 countries, you’ll have a unique opportunity to find products and suppliers that offer the best HVAC solutions from around the world. Many of these companies use AHR Expo as their only point of entry into the U.S. market, so this may be your only chance to see them. For a list of exhibiting companies go to: AHR Expo List of Exhibitors
Experience the new technology being offered by Belimo at AHR Booth 733.
Globe Valve Actuators and Retrofit Linkages promise easy installation with more power and flexibility.
No two applications are exactly alike; new or old, they all vary in their demands. Whether it’s high pressure steam or difficult installations, New Generation Globe Valve Actuators are designed to adapt to these challenges offering easy installation and fi eld adjustability. They can be adapted to most globe valves, regardless of make.
- Travel ranges of up to 2” (50mm).
- Multiple voltage options (24V and 120-230V).
- Steam inlet rating up to 100 psi.
- One universal linkage which can retrofit most globe valves, regardless of make.
- Quick connect coupler for easy installation.
- Field selectable fail-safe position switches.
- Lower power consumption during operation.
- Easy selection process, minimized inventory.
ZIP Economizer™ - Airside economizing that delivers what owners expect.
Until now, economizing solutions have left a lot of room for error. The ZIP gets efficiency strategies back on track with easy setup, automatic code change over temperatures, and superior troubleshooting capability. Users know instantly when failures occur and the ZIP helps them quickly pinpoint the problem and address it. With the following features, the ZIP
leaves nothing to chance:
- Easy-to-read automotive grade LCD display delivers clear live status information.
- ZIP Code patented technology will automatically recognize your climate zone.
- Plug and Play self-configuring.
- Integrated onboard test sequence that ensures effortless compliance.
- Fault Detection and Diagnostics (FDD) troubleshoot faults and initiates alarms.
- Onboard help for setup or troubleshooting.
The Fast Route to Reliable Energy Savings.
Belimo Energy Valve™ keeps you informed on coil performance.
Achieving the ideal amount of heat transfer in a given coil is critical for overall system efficiency. When this does not occur, pumps, chillers and boilers must work harder to maintain space setpoints, a scenario that creates substantial energy waste. This is especially problematic in large chilled water systems because it frequently results in low Delta T – meaning that return water temperatures to the chiller are lower than the designer intended which undermines chiller plant efficiency. Many of these problems can only be addressed at the coil. Fortunately, the Energy Valve helps detect and address scenarios that commonly impact coil performance and thus system efficiency.
- Improve coil Delta T by utilizing Belimo Delta T Manager™.
- Save pump distribution energy by eliminating coil overflow.
- Improve plant performance.
- Reduce unwanted chiller or boiler staging by improving plant DT.
- Achieve coil performance that follows the calculated design flow rates exactly.
- Simplified valve sizing and selection, no Cv calculations required.
- Provides data to the BAS, enabling continuous commissioning of coils.
EF Spring Return Actuators provide a cost effective and flexible solution that will deliver years of dependable performance.
- Reduce wiring and installation time while offering manual override on large dampers.
- Higher torque offering (270 in-lbs) in a single, direct coupled actuator can take the place of two classic AFs.
- NEMA 4 (UL Type 4, IP 66) option to meet tough environmental conditions without having an additional housing.
- Effectively operates a 66 square foot damper.
- MFT models offer many proportional control functions and DC voltage feedback signals that can come programmed from the factory or adjusted in the field.
Learn more at www.belimo.us.