Analysts of Pneumatic Systems Limited. Conserving energy since 1976 Training Manual • Energy conservation of HVAC • Innovative new solutions to solve the problem of climate change • Range of services include consulting, design, conservation, promotion, and training • $100 million in energy savings by retrofitting heating and cooling systems to be more energy efficient • Three person team prevented over 60,000 person years of green house gas emissions Respecting our common environment on which we all depend, you may use this manual for training purposes at no charge. This manual may not be altered and presented as APS's information.
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HVAC SYSTEM LOGIC & PNEUMATIC CONTROL COURSE & HVAC/COVID VIRUS TRANSMISSION EXCESSIVE FRESH AIR VENTILATION IMPACT ON GLOBAL WARMING & BOURDON TUBE CHARACTERISTIC ASSESSMENT REGARDING POTENTIAL PROOF OF Wout > Win & REPORTS REGARDING THE HYDRAULIC DISPLACEMENT MOTOR PROVING THAT Wout > Win IS ACHIEVABLE A P S PHONE (905) 640-2333 FAX (905) 640-2444 analystsofpneumatic@bellnet.ca http://www.apscontrols.org RESPECTING OUR COMMON ENVIRONMENT ON WHICH WE ALL DEPEND, YOU MAY USE THIS MANUAL FOR TRAINING PURPOSES AT NO CHARGE. THIS MANUAL MAY NOT BE ALTERED AND PRESENTED AS APS'S INFORMATION. FREE FILE ON WEB SITE IN THE TRAINING SECTION.
PREFACE Every building and control system is different from all others, making it an impossibility to foresee each situation you will face in the field. The training is intended to allow one to understand the operational range relating to each type of component and present control concepts as simply as possible. The performance of each control set up depends on the quality of the design and commissioning. The responsibility of each system rests on the persons working directly with the system. Normally the end sequence can be achieved by more than one combination of control components. Typically an assessment of the existing control system determines the best approach in retrofitting a system from a cost point, using as much of the existing components as possible. You must have a clear vision of the final performance level for your system considering safety, health, comfort, energy, etc. You must assure that the system has all information available that would allow good decisions with your performance goal in mind. You must also assure that the control system has proper control over all the functions required to achieve the performance level desired. Under any set of conditions the control system should position devices identically to what an intelligent person would do, if manually operating the mechanical system. The most positive assessment is via directly viewing the dampers, valves, etc. Computer screen shots, via the BAS, if the sensors are calibrated properly, can be a means of identifying illogical control situations. Look at them thoughtfully. The logic in this text is presented with pneumatic controls; however, it equally applies to DDC, electronic and manual control of mechanical HVAC systems. A nightschool class, comprised of experienced HVAC Professional Engineers and control service mechanics, retrofitted a school’s control system, based on the logic in this course. They reduced the gas consumption by 50% and the electrical consumption by 27%, translating to an annual reduction of 248 tons of carbon dioxide not entering the atmosphere, as well as the other pollutants associated with combustion of fossil fuels. The project represented about one person-week of work, eliminating the equivalent pollution of approximately thirteen North Americans for one year. During your career you may easily eliminate an impact equaling thousands of person-years of pollution. The United Nations scientists stated publicly in 2018 that we have less than twelve years to find real solutions to burning fossil fuels, producing greenhouse gasses. You can be a contributing factor in producing solutions, addressing climate change. i
ii The following is a suggested path to specific pages in the Training Manual hopefully inspiring the reader to think deeper on why they unconditionally accept established procedures and physical laws. Why Care: Based on the BBC survey on the psychological impact on our youth, the majority of our children often worry about global warming. (page 11.189) A recent news report stated that more than 60% of Canadian adults are very concerned with global warming. We are needlessly increasing operational costs via wasted energy. We are damaging the planet rather than respecting the planet. We have the technology, to significantly help in our environment, which is being dismissed. The APS training manual addressed in categories: 1) HVAC energy performance improvements: Pages 6.44 to 6.47 present sample energy reductions for buildings calculated by the owners. Some examples of illogical control systems hiding energy waste are presented on pages 5.38 to 5.43A-G. Case studies pages 8.63 to 8.159 present some case studies focusing on logic advanced over much of current industry approaches. 2) COVID/HVAC relationship to escalated global warming: Current increased minimum fresh air ventilation is escalating global warming. The disabling of Demand Ventilation Control (DVC) is escalating global warming. Current scientific data and a response from ASHRAE’s Epidemic Task Force (Page 11.191) may imply the current ventilation solutions are not logical in COVID virus transmission reduction, but damaging to the planet via escalated global warming. (Pages 11.187 to 11.209) Critical data is missing in this area of research. (Page 11.203) The ventilation changes from conservation logic (DVC) is increasing GHG emissions by up to 700% and direct heat injection into the atmosphere by up to 670% at many HVAC fan systems that have been altered to mitigate COVID transmission. (Page 11.190) 3) Hydraulic Displacement Motor: Some scientists/engineer positive peer reviews on pages 13.276 to 13.282. A patented system producing completely clean mechanical work. Patent office link: https://worldwide.espacenet.com/inpadoc?submitted=true&DB=EPODOC&CC=US&NR=2002178719&KC=&F (NOTE: Patent examiners in the PCT, European, Canadian and USA offices passed it.) The fundamental science explained on pages 13.233 to 13.237. (Also page 13.254) System application drawings and performance graph on pages 13.295 to 13.298. The invention challenges the Laws of Thermodynamics; therefore, I suggest a thought process to determine if you accept the Laws of Thermodynamics based on faith or scientific proof on pages 13.300 to 13.304. A suggested logic path is on page 13.313.
iii 4) Bourdon tube investigation: Some industry experts’ opinions are that a Bourdon tubes’ volume does not change when flexing, while the remaining experts contacted have no data on the subject. Pascal’s Principle is an accepted scientific fact. If the Bourdon tube does not change when flexing and Pascal’s Principle is valid, a demonstration that work output can exceed work input may be developed. (Wout ˃ Win) The experiments presented on pages 12.210 to 12.231 tested the industry experts’ opinion that the Bourdon tube’s volume does not change. The results to date did not confirm that opinion and indicated that the volume does change; however, air bubbles in the Bourdon tube may have simulated change via compression and decompression. We cut open a Bourdon tube and the interior had rough areas that could trap air bubbles. The experiments could have proven the industry experts’ opinion true, but cannot prove their opinion is untrue. Air bubles in the experimental tube may have simulated a volume change. The patent (US 7,467,517, B2), applying Pascal's Principle to Bourdon tubes is linked below: Some scientist/engineers’ opinions: https://static1.squarespace.com/static/5ee6829b4abd4867f862c3ca/t/61e6fb5a7ea4d658250bc320/1642527582218/SCIENTIFIC+AND+ENGINEERING +OBSERVATIONS+AND+OPINIONS.pdf The industry should be training our service and commissioning persons to be highly sensitive to their work being important in the Climate Change mitigation effort. The men at APS have each eliminated over 20,000 person years of pollution via applied common sense. Most control service persons are potentially capable of the same if provided with the training and opportunity. Regards President APS https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/7467517 The Hydraulic Displacement Motor science has been dismissed based only on faith in the laws of Thermodynamics, with no challenge to the actual system design drawings presented on pages 13.295 to 13.298. SIEMENS had one of their control experts examine the drawings and he initialed all of the drawings with no changes, which confirmed our applied control logic. CLICK HERE ^
CONTENTS SECTION ONE (CONTROL KNOWLEDGE QUIZ) -Quiz (Answers 10.177 to 10.183) SECTION TWO (CONTROL ACTION & DEVICES) -Component normal positioning and action -Two way valve -Damper motor (actuator) -Pilot positioned (positive positioning relay) on damper motor -Pneumatic and electric devices SECTION THREE (THERMOSTATS) -Non-relay thermostat -Relay thermostat -Change-over calibration board -Calibration procedure -sample of thermostat air use an leak impact on compressor SECTION FOUR (TRANSMITTERS, CONTROLLERS & RECEIVER CONTROLLERS) -Pneumatic transmitters -Pneumatic transmitter compressed air consumption -Controller and receiver controller -Control loops -Control loop components -Controller and receiver controller functions SECTION FIVE (BASIC LOGIC) -Heating/cooling input -Outdoor air relative to coolest demand hotwater reset schedules -Mixed air purposes -Some areas of hidden energy losses in control systems SECTION SIX (SOME CLIENT CALCULATED ENERGY REDUCTION IMPACTS) -Durham Board, Scarborough Board, Etobicoke Board, Wycliffe SECTION SEVEN (SOME TYPICAL FAN SYSTEMS) -100% FRESH AIR (ANSWERS 10.185.) -SINGLE DISCHARGE MIXED AIR (ANSWERS 10.186) -MULTIZONE -DUAL DUCT -VAV PRESSURE INDEPENDENT -VAV PRESSURE DEPENDENT -VAV FAN POWERED BOX -BYPASS (DUMP) BOX -INDUCTION -UNITVENTILATOR WITH FACE & BYPASS -UNITVENTILATOR WITH HEATING VALVE -UNITVENTILATOR WITH FACE & BYPASS (3 PIPE THERMOSTAT) -FAN YSTEM WITH MANY DESIGN ERRORS (ANSWERS 10.184) iv
SECTION EIGHT (SOME CASE STUDIES) -SINGLE ZONE -MULTIZONE -EVAPORATIVE COOLING OPPORTUNITY VIA SPRAY HUMIDIFIERS -ENTHALPY COMPARATOR CIRCUIT (APS COMPARED TO JOHNSON CONTROLS) -ENTHALPY/DRY BULB COMBINED LOGIC -HUMIDEX CIRCUIT -HOT WATER RESET COMPARING CONVENTIONAL TO COOLEST ROOM LOGIC -VAV PERFORMANCE CASE STUDY -RESIDENTIAL NIGHT SET BACK SECTION NINE (COMPRESSED AIR CARE) COMPRESSED AIR CARE SECTION TEN (ANSWERS) QUIZ ANSWERS FAN WITH ERRORS 100% OSA REQUIREMENTS MIXED AIR REQUIREMENTS SECTION ELEVEN (HVAC/COVID VENTILATION/GLOBAL WARMING) REQUIRED MISSING DATA ISSUE DETAILED EXPLANATION OF HVAC/COVID VENTILATION/GLOBAL WARMING SECTION TWELVE (BOURDON TUBE INVESTIGATION ASSESSING Wout > Win) SECTION THIRTEEN (HYDRAULIC DISPLACEMENT MOTOR REPORTS) FUNDAMENTAL SCIENCE PATENTS, DEVELOPMENT AND HISTORY TEST RESULTS REGARDING EFFICIENCY DIFFERENTIAL ASSESSMENT REGARDING W = P∆V AND W≠ P∆V (REPORT #1) ASSESSMENT REGARDING W = P∆V AND W≠ P∆V (REPORT #2) A NEW VIEW OF THERMODYNAMICS SIEMENS' CONTROL EXPERT ASSESSMENT v POTENTIAL STUDENT INVOLVEMENT IN MOVING SCIENCE AHEAD Patented nvention summary. Increased work assessment applying formulae W=FD and W = P∆V. Logic path to understand the science of the clean energy invention. Request for assistance from concerned persons regarding climate change issues. SECTION FOURTEEN: ANSWERING THE MOST COMMON QUESTION. HOW DID YOU THINK OF THESE INVENTIONS? Source of knowledge for all inventions and developments Registered letter and envelope to the inventor from September 30, 1972 of basic science and the benefit intent regarding the first patented invention. Responsibility to protect the earth for atheists and Christians. PSYCHOLOGICAL IMPACT OF CLIMATE CHANGE ON YOUTH. SECTION FIFTEEN: STUDENT CLIMATE CHANGE MITIGATION COURSE
SECTION ONE (CONTROL KNOWLEDGE QUIZ) -Quiz (Answers on pages 10.177 to 10.183) 1.1 to 1.7 PURPOSE OF SECTION—Allow self assessment of reader before course.
CONTROL QUIZ This quiz should allow you an indication of your basic control understanding before studying the control course. This quiz does not cover every aspect of potential situations you will face. The hope of the course is bringing you to a comfort level with the various control techniques available to you in solving challenges. Only select True or False if you are positive. Record your number of correct, incorrect and unanswered items. After studying the course repeat the quiz comparing the two results. The answers are at pages 10.177 to 10.183 in this training manual. PNEUMATIC THERMOSTATS -1- In a reheating application you may find a reverse acting thermostat controlling a normally closed valve. True False -2- Two pipe relay thermostats usually are capable of passing a greater volume of compressed air than a one pipe thermostat. True False -3- Day/night and summer/winter thermostats alter modes via a change in main air pressure. True False -4- There are several different pressure combinations used for day/night and summer/winter changeover in the industry. True False -5- Relay type thermostats bleed a small amount of compressed air most of the time. True False -6- Two thermostats are required to control a room with a VAV box and a heating coil. True False -7- If the flapper nozzle (leak port) is plugged on a direct acting thermostat, controlling a normally open heating valve, the room will likely over-heat. True False -8- If an operator accidentally bends the bimetal away from the flapper nozzle (leak port) on a reverse acting thermostat controlling a normally closed cooling valve, the room will likely over-heat. True False -9- The sensitivity of a thermostat is the relationship of temperature change to output signal (branch signal) change. True False -10- The sensitivity can be changed on most thermostats, but recalibration is required after that adjustment. True False 1.1
-11- If the main air and signal connections are reversed the thermostat typically makes an air hissing noise. True False -12- If the main air and signal connections are reversed the thermostat will still control, but a little slower to react. True False -13- If a thermostat is controlling a normally open heating valve and a normally closed cooling valve with identical spring ranges, the temperature will control, but energy will be wasted. True False -14- An air leak on the branch of a relay thermostat can consume more compressed air than fifty extra thermostats working normally on the system. True False -15- The maximum volume of compressed air thermostats can pass out their branch lines varies based on different manufacturers. True False -16- In an existing system, another manufacturer’s thermostat may usually be used as long as the change-over point is adjusted to match the existing system and the thermostat is the same action. True False -17- When calibrating a day only thermostat you set the dial at the current room temperature and adjust the branch signal to midrange of the valve or damper being controlled. True False -18- The change-over point is not adjustable on summer/winter or day/night thermostats. True False -19- In one stage of calibrating a thermostat, you must set the branch pressure for midpoint of the controlled device and use your breath to heat the bi-metal, checking for proper operation. True False -20-When you heat the thermostat in question 19, the pressure will go lower with a direct acting thermostat. True False VALVES -1- Normally open valves allow their maximum fluid flow when their diaphragm pressure is below the bottom end of the spring range. True False -2- The bench stroking spring range of a valve is the pressure difference between the pressure required to start the stroking of the valve and the pressure when the valve is fully driven. True False 1.2
-3- The stroking spring range of a valve is the same on the bench as it is in service with the pumps running or steam pressure present. True False -4- The stored force in the spring of some control valves can be as high as 1800 pounds, setting the potential for injury or death if disassembled incorrectly. True False -5- It is best to remove the stem from the packing box to completely clean the stem and packing box before installing the new packing rings. True False -6- Two valves the same pipe size will not have the same flow capability if their CV factors are different. True False -7- There is no difference between three-way diverting valves and three-way mixing valves. True False -8- Normally open valves are usually installed on heat exchangers serving domestic hot water. True False -9- The system differential pressure of the water or steam tends to widen the in service stroking spring range compared to the bench stroking spring range of a valve. True False -10- A valve installed backward in a system may cause a hammering noise as it attempts to modulate. True False -11- A pilot positioner on a valve eliminates the effect of system differential pressure on the valve`s stroking range. True False -12- When the hot water supply temperature is hotter than required by the served area with the greatest heating requirement, the seats and discs on the system’s valves tend to experience more wear and tear, shorting the valves’ life span. True False Automatic Dampers -1- The normal position of a damper is the position it reaches with no air pressure on the actuator. True False -2- Most often the fresh air and exhaust air dampers are normally open and the return air damper is normally closed. True False -3- There is never danger of injury from an actuator`s spring when replacing a diaphragm. True False 1.3
-4- Exposing an actuator to pressure higher than recommended by the manufacturer could result in damage to the building, personal injury or death. True False -5- The return air damper should start closing before the fresh air damper starts opening. True False -6- If the return air is closed and the fresh air damper is closed there is no danger of collapsing duct work. True False CONTROLLERS -1- A controller, with its sensing mechanism, senses the controlled condition directly. True False -2- Normally a controller has an averaging sensing element when sensing the mixed air. True False -3- If a fluid or gas filled sensing element is broken, the controller will believe the temperature suddenly increased. True False -4- Sensitivity and throttling range are the same. They relate to the relationship of the output pressure change relative to a specific temperature change. (example: 5#/F°) True False -5- Normally the slower the controlled condition potentially changes, the higher the sensitivity (lower the throttling range) (lower the proportional band )on the controller. True False -6- A controller acting as a mixed air low limit typically has a set point of 55°F to 60°F. True False -7- The sensitivity is not normally adjustable on controllers. True False -8- Throttling range is the amount of the sensed variable change required to stroke the controlled device from fully open to fully closed. True False -9- A single controller can be used to satisfy only one function in a control circuit. True False 1.4
RECEIVER CONTROLLERS AND TRANSMITTERS -1- Transmitters do not normally control anything; they just sense and report the condition to receiver controllers and indication gauges. True False -2- Receiver controllers may have as many as five connection ports. True False -3- The majority of SIEMENS, TAC, Johnson Controls and Honeywell transmitters are two pipe instruments. True False -4- The indicating pressure range of transmitters is normally 5 PSIG to 18 PSIG. True False -5- Applying 9 PSIG to a 0°F to 100 °F transmission gauge would cause the gauge to indicate 50°F. True False -6- A two position receiver controller can gradually modulate a control valve from fully open to fully closed. True False -7- Some receiver controllers provide a restricted air supply to its associated transmitter and some others require an external restricted air supply to the associated transmitter. True False -8- If a receiver controller that can provide restricted air to its associated transmitter is receiving main air at variable pressures, its internal restrictor must be blocked and a constant main air external restrictor must be added. True False -9- If the transmission line is cut between the receiver controller and the (0°F to 100 °F) transmitter, the receiver will believe the temperature is above 100 °F. True False -10- A transmitter can only report to one receiver controller. True False -11- Room temperature transmitters look like a thermostat with no dial adjustment. True False -12- Proportional band, gain and sensitivity all refer to the same function in receiver controllers. True False -13- Receiver controllers may be arranged to automatically raise and lower a temperature of one medium based on a variation sensed in another medium. True False 1.5
-14- Receiver controllers with a CPA can have their set point adjusted from remote locations via pressure changes. True False RELAYS -1- Pneumatic relays allow design logic achieving almost any sequence of events required. True False -2- A two input high selector averages the input signals. True False -3- A volume boosting relay may also be used as a two input low selector. True False -4- A snap acting air switching valve may be piloted by a two position controller or a modulating controller. True False -5- A modulating receiver controller may pilot a gradual air switching valve. True False -6- A reversing relay can effectively change a direct acting signal into a reverse acting signal and offset the signal. True False -7- Multi high-low selector indicates the highest input signal on its H output port and the lowest input signal on its L output port. True False -8- A minimum positioning relay assures the fresh air dampers are closed at night. True False -9- A biasing relay (ratio relay) allows co-ordination of heating and cooling in a logical sequence. True False -10- If two thermostats, set for 70°F, are averaged with one room at 80°F and the other at 60°F the average will be 70°F. The comfort in the occupied space will be acceptable. True False -11- Pilot positioners (positive positioning relays) are used on valves and damper actuators to position the devices accurately, compensating for varying resistance, as well as allowing alteration of the stroking range and start point of the devices stroke. True False -12-Relays are available to add or subtract a determined amount of pressure from another variable pneumatic signal at a constant rate. True False -13 A PE switch passes control air when energised. True False 1.6
SAFETY LOOPS -1- Low limits (sometimes called freeze stats) have an averaging element and shut down the fan if the air is too cold. True False -2- High limits (sometimes called fire stats) should be only installed in the supply and mixed air. True False -3- Circuits sensing the coil water temperature with an electric thermostat (45°F) and the water electric flow switch wired in series, also have an outdoor temperature electric thermostat (45°F) wired in parallel with the series circuit previously mentioned. True False -4- Low and high limit circuits may be fully electric or pneumatic with a pressure switch. True False -5- Normally the safety circuit should be wired through the automatic side of the starter switch and not the hand side of the switch. True False -6- Static pressure high limit on VAV systems shut down the fan before the pressure reaches the system’s static control point. True False -7- If a low limit is causing nuisance fan shut downs, it is usually OK to jumper the contacts of the low limit to keep the fan running. True False -8- If the high pressure relief valve on the compressor keeps blowing off, you should remove it and plug the hole. True False -9- The pressure switch on the compressor can be jumpered, if defective, until you get a new one. True False -10- The steam valve on the heat exchanger for domestic hot water should fail closed. True False 1.7
SECTION TWO (CONTROL ACTION & DEVICES) -Component normal positioning and action 2.8 -Two way valve 2.9 -Damper motor (actuator) 2.10 -Pilot positioned (positive positioning relay) on damper motor 2.11 -Pneumatic and electric devices 2.12 to 2.19 PURPOSE OF SECTION Present applicable components and logic. Any logic statement regarding event sequencing, while controlling valves, dampers, etc. can be achieved by proper application of the control relays on pages from 2.12 to 2.18.
COMPONENT NORMAL POSITIONING AND ACTIONS NORMALLY OPEN VALVE A normally open valve allows the flow of fluid through the valve’s body when air pressure is removed from the valve actuator’s diaphragm. NORMALLY CLOSED VALVE A normally closed valve disallows flow of fluid through the valve’s body when air pressure is removed from the valve actuator’s diaphragm. NORMALLY OPEN PRESSURE SWITCH A normally open pressure switch disallows electrical flow through the pressure switch’s contacts when pressure is removed from the pressure switch’s diaphragm. NORMALLY CLOSED PRESSURE SWITCH A normally closed pressure switch allows electrical flow through the pressure switch’s contacts when pressure is removed from the pressure switch’s diaphragm. DIRECT ACTING CONTROL A direct acting control increases its output (branch) signal on an increase in the sensed medium. REVERSE ACTING CONTROL A reverse acting control decreases its output (branch) signal on an increase in the sensed medium. PROPORTIONAL AND TWO POSITION CONTROL Proportional control allows output branch line signals to be infinitely variable between 0 PSIG to the supply air maximum pressure. Proportional control allows modulation. Two position control only allows the output branch pressure to be 0 PSIG or equal to the maximum supply air pressure. There is no modulation with two position control. EXAMPLES -1- A direct acting thermostat controls a normally open heating valve. As the thermostat senses an increase in room temperature it increases its output signal driving the normally open valve closed to reduce heat gain in the room. -2- A direct acting thermostat controls a normally closed cooling valve. As the thermostat senses an increase in the room temperature, it increases its output signal driving the normally closed cooling valve open providing cooling to the room. 2.8
TWO WAY CONTROL VALVES NORMALLY OPEN VALVE NORMALLY CLOSED VALVE Compressed air drives the valve closed. Compressed air drives the valve open. The return spring forces the valve open The return spring forces the valve closed on a decrease in air pressure. on a decrease in air pressure. AIR CONNECTIONS DIAPHRAGMS DIAPHRAGM PLATES ACTUATOR RETURN SPRINGS PACKING SEALS SET SCREWS STEMS DISC ASSEMBLIES VALVE SEATS FLUID FLOW VALVE BODIES Pneumatic valves stroke through ranges dependent on the range of the return spring. Some valves have fixed start points while other valves may have the start point altered via spring tension adjustment on the actuator. The spring range on the valves specification sheet is a bench spring range. Typically, in a system, a normally open valve with a bench spring range of four PSIG to eight PSIG will start at four PSIG, but close above the eight PSIG bench closing point. The fluid system differential pressure, from the supply to the return, causes a force against the disc assembly, shifting the spring range closing point of eight PSIG, for example, to ten PSIG. Valves must be installed with the fluid flow as illustrated. If a valve is installed backwards, it will usually cause hammering in the pipes just as the valve is close to the normal closing point. Honeywell and some Johnson Control valves have a normally open body, with an actuator that drives the valve closed when no pressure is on the diaphragm. These valves have to be considered normally closed in the logic of a system. Some older Johnson Control valves have the potential to be very dangerous during servicing. Consider the illustration of the normally open valve. If the disc assembly is detached from the stem, the set screws are the only means of holding the spring in the actuator. Some valves have an 8R actuator and a valve range of nine to thirteen PSIG. In this situation, the actuator could be thrown, if the set screws are loosened, with a force around fifteen hundred pounds. It could cause severe injuries or death. 2.9
DAMPER ACTUATOR (MOTOR) Damper actuators position automatic dampers via a control pressure entering the damper actuator through the air connection. The air pressure is distributed evenly over the face of the diaphragm, exerting a total force on the diaphragm cup, which transfers that force to the shaft. The spring resists the force generated by the air pressure, returning the actuator to its normal position when air pressure is removed. Damper actuators have a spring range (throttling range). The spring range on an actuator’s specification sheet is based on the actuator with no load. An actuator with a spring range of 8 PSIG to 13 PSIG will start to move at 8 PSIG and reach the end of its stroke at 13 PSIG. There are many spring ranges with the most common being 8# to 13#, 5# to 10#, 3# to 7#, 2# to 12#, 3# to 13# and 10# to 15#. Some Barber Colman and some older Powers damper actuators allow shifting of the spring range via an adjusting nut, which has the shaft running through its middle. The diaphragms are normally replaceable, but not always. Springs in pneumatic actuators can be potentially very dangerous; therefore, you should respect the power stored in the spring while disassembling an actuator. When replacing a diaphragm, remove air pressure from the actuator and then back off the actuator housing nuts just enough to separate the actuator housing cap from the actuator housing. Push on the actuator housing with your hand giving you a sense of the power of the spring. If this is difficult to push, take appropriate steps to protect yourself replacing the actuator housing bolts, one at a time, with longer bolts and nuts for adjustment. Do not apply air pressure higher than recommended by the manufacturer, as you may: -1- damage the actuator -2- injure or kill yourself or others ACTUATOR ACTUATOR HOUSING HOUSING BOLT DIAPHRAGM CUP (4 TO 8 TYPICAL) SPRING RETENTION NUT SHAFT AIR CONNECTION ACTUATOR HOUSING CAP RETURN SPRING DIAPHRAGM 2.10
DAMPER ACTUATOR (MOTOR) WITH POSITIVE POSITIONING RELAY Damper actuators with no positive positioning (pilot positioner) relay often position the damper at a different degree of opening for the same pressure when the pressure is increasing to that pressure or decreasing to that pressure. As the damper increases its frictional impact with dirt and age, positioning will be different for the same pressure relative to when the damper was new. Positive positioners present three benefits: -1- The throttling range of the controller is adjustable. On the old Honeywell the six screws under the round cap allowed selection of three, five or ten pound ranges. The position of the spring connected to the linkage from the shaft allows span adjustment for Johnson Controls, Barber Colman and SIEMENS positive positioners. The feedback springs can be changed to have three, five and ten pound spans on the new Honeywell, Kreuter and Robertshaw positive positioners. -2- The feedback spring allows the positioner to “know” the percentage of stroke, regarding the actuator’s shaft, at all times. The positive positioner will apply air pressure to the actuator’s diaphragm from main air pressure to zero PSIG maintaining the damper exactly at the percentage of stroke demanded by the controller. The start point for the stroke is adjustable. -3- Positive positioners boost a low volume signal to a high volume signal. DIAPHRAGM CUP ACTUATOR HOUSING CAP ACTUATOR HOUSING RETURN SPRING SHAFT AIR CONNECTION DIAPHRAGM POSITIVE POSITIONER POSITIVE POSITIONER’S FEED BACK SPRING SIGNAL MAIN AIR CONTROLLER SIGNAL 2.11
CONTROL RELAYS 0 15 30 5 10 20 25 MINIMUM MIXED AIR MINIMUM POSITIONER SIGNAL POSITIONER HS P IN OUT EP AIR TO EP AIR TO DAMPERS M B DAMPERS MIXED IN AIR PRV MPR SIGNAL SIEMENS MULTIPURPOSE RELAY MINIMUM POSITIONER REVERSING RELAY BIASING RELAY (-1-) MIXED AIR (-2-) (-3-) SIGNAL SIGNAL TD TR TD TR SIGNAL TD TR EP AIR S R TO EP AIR S R TO EP AIR S R TO DAMPERS DEVICE DEVICE MPR RR BR Minimum ventilation is some times achieved via a pressure reducing valve (PRV) and a high selector (HS), as illustrated above. If the controller signal drops below the pressure required keeping the dampers at or above the minimum ventilation rate, the HS passes the PRV signal to the dampers, maintaining minimum ventilation. Minimum ventilation is sometimes achieved via a minimum positioning relay (MPR). The MPR is set at a pressure which holds the fresh air damper open enough to assure at least minimum ventilation when the controller signal is below that pressure. SIEMENS multipurpose relay may used as: -1- A minimum positioning relay (MPR), as per the top left hand MPR in this illustration. -2- A reversing relay (RR), which reverses the input signal (TR) and allows biasing of the signal. Example: If the signal increases by 2 PSIG, the output (R) decreases by 2 PSIG. The output may also be biased relative to the signal. Example: The relay may be set for 10 PSIG signal provides 10 PSIG output: you may adjust the relay to 10 PSIG provides an out put pressure other than 10 PSIG suiting the sequence of the circuit. -3- A direct acting biasing relay (BR), which offsets the signal (TD) in the output signal (R), and remains a direct acting signal. This is used to sequence devices, eliminating function over-laps (heat/cool, preheat/reheat, face & bypass damper/valve, etc.) NOTE: The TAC AKR-40605 is also a multi use relay. The AKR-40605 may be used as a minimum or maximum positioning relay, a 1:1 ratio relay (as #3 SIEMENS illustrated)), a two signal low sector or a manual positioner. 2.12
M P B CONTROL RELAYS REVERSING BIASING RELAY RELAY M M P B P B Reversing relays increase their branch signal in response to a decrease in their pilot signal. Most have a 1:1 relationship. Johnson Controls made a reversing relay with a 1:2 relationship. The branch pressure can be biased for sequencing purposes. Biasing relays increase their branch signal in relationship to the pilot signal. The branch signal may be off set to a different pressure than the pilot signal. The branch may increase at ratios of 1:1, 1:2, 1:3.33 or 1:5. RATIO RELAY P TURNDOWN RATIO RELAY (KREUTER) M B Ratio relays increase their branch signal at a fixed ratio relative to their pilot signal. The ratios are 1:2, 1:4, 1:6. Reducing ratio relays decrease the branch signal relative to the pilot signals. The output signal cannot be biased with these relays. The turndown ratio relay allows the branch signal to be biased relative to the pilot signal. The branch signal may reduced at a selectable ratio via a dial on the relay. 2.13 GRADUAL SWITCH Gradual switches can be one or two pipe. They can be used as a minimum positioner as the PRV on page 2.12. They are very useful in simulating transmission signals while calibrating receiver controllers.
CONTROL RELAYS _________________________________________________________________________________________ LOW HIGH SELECTOR SELECTOR (1) (B) INPUT OUTPUT INPUT OUTPUT (M) INPUT INPUT _________________________________________________________________________________________ AIR MULTI/HIGH/LOW SWITCHING SELCTOR VALVE PILOT (P) NC C SIX INPUTS NO Low selectors receive two input signals and produce an output signal matching the lower input. Low selectors often can be used as a volume booster relay, depending on the manufacturer. High selectors receive two input signals and produce an output signal matching the higher of the two inputs. Air switching valves are open from the NO to the C port when the pilot signal is lower than the valve’s spring range. The valve is open from the NC to the C port when the pilot pressure is higher than the valve’s spring range. Gradual acting air valves must have a two position pilot signal (0 PSIG or 15-20 PSIG). Snap acting air valves may have a gradually changing or two position pilot signal. Some air valves have adjustable switching points. H M L Multi-high/low selectors receive more than two input signals. Manufacturers allow a variety of options. The highest signal is duplicated as the high output signal and the lowest signal is duplicated as the low output signal. Both the multi-high and multi-low can be built with check valves and a .005” restrictor. Flow from each of the selected signals, through a check valve, to a common line and the .005" restrictor bleeding to atmosphere from the common line will produce the highest signal. Flow through check valves, to each of the selected signals from a common line which has main air entering the common line through the .005" restrictor produces the lowest signal on the common line. 2.13A
Averaging relays have two inputs (some have four), main air and branch ports. The branch port signal is the average of the input signals. CAUTION: One input signal may indicate an extremely hot room and the other input signal may indicate an extremely cold room, but the average indicates that all is well. Pilot positioners (positive positioners) sense the stroke of the valve or damper actuator from 0% to 100%. The controller signal does not go directly to the valve or damper actuator. It goes only to the pilot positioned indicating the required percentage of stroke. The pilot positioned uses from full main air pressure to zero PSIG positioning the device as requested. Addition relays are also available from Kreuter and have two input signals, main air and branch signal ports. The branch signal is the sum of the two input signals, but cannot exceed the main air pressure. The branch signal may also be biased. They are useful in conservation loops if you wish to simulate a transmission signal greater than the actual condition. Subtraction relays are available from Kreuter and have two inputs, main air and branch ports. The branch signal is the product of subtracting port 2’s signal from port 3’s signal (KREUTER). The branch signal can also be biased. They are useful in conservation loops such as enthalpy comparison between outdoor air enthalpy and return air enthalpy. CONTROL RELAYS SUBTRACTION ADDITION RELAY RELAY M B M B INPUT INPUT INPUT INPUT AVERAGING POSITIVE POSITIONER RELAY (PILOT POSITIONER) DAMPER VALVE ACTUATOR B M M B P P INPUT INPUT B M 2.14
One type of transducers are the means of using an analogue pneumatic signal (3#-15#) to generate an analogue electrical signal. (05VDC,0-10 VDC or 4-20ma) Another type is the means of using an analogue electrical signal (0-5VDC, 0-10VDC or 4-20ma) to generate a 3#-15# pneumatic signal. They are available as relay and non-relay transducers. Electric thermostats allow or disallow electrical flow based on the controller’s set point and the state of the medium the control is sensing. They are often used in safety circuits. Electro/pneumatic (EP) valves, also referred to as solenoid air valves (SAV) are the means of allowing or disallowing pneumatic signals in a circuit. Be sure the voltage rating is correct and the air pressure is below manufacturer’s recommendations. TRANSDUCERS ELECTRIC CONTROLS Pressure electric switches and mercoid switches are the means of controlling an electrical signal via a pneumatic signal. They come normally open, normally closed or allow a choice when wiring. Do not exceed the pressure, voltage or amperage recommended by the manufacturer. PNEUMATIC/ELECTRIC COMPONENTS PRESSURE MERCOID ELECTRO/PNEUMATIC VALVE (EP) ELECTRIC (PE) SOLENOID AIR VALVE (SAV) (PE) C NO NC 2.15
RES. Low limits are sometimes called Freeze Stats. The coil in a fan can still freeze even after the low limit has shut down the fan in some situations. They do not have averaging elements. The element will cause the low limit to trip at its set point (40°F) if any one foot of the element senses a temperature below set point. They can be electric or pneumatic with a PE being controlled by the pneumatic low limit. They can be manual reset or automatic. High limit circuits are sometimes installed using sprinkler heads, with the correct temperature rating for the locations and a pressure switch fed by restricted main air. If any sprinkler head melts, the air is bled from the common line down-stream of the restrictor and the pressure switch opens its contacts shutting down the fan system. If the compressed air supply fails, the fan system will shut down, as a high limit situation will be simulated. High limits shut down the fan system if they sense a temperature above their set point. The set point should be no more than 50F° above the normal highest temperature in the duct. They usually have to be manually reset after they have shut down the fan system. They can be electric or pneumatic. If they are pneumatic, they cycle a pressure electric switch attaining the same result as the electric units. Some have adjustable set points, while some have fixed set points. Differential pressure switches open and close their electrical contacts based on pressure variation sensed by the switch. They normally have low and high pressure connections. Often they are used providing status on fans or used as safeties on electric heating coils preventing the coil from heating when the air flow stops. They are normally electric devices, but pneumatic units exist, which must cycle a pressure electric switch, attaining the same result. If a diffuser is blocked the switch will sense pressure, but no air flow is allowed by the blockage; therefore, the electric coil may still be damaged. SAFETY CIRCUIT COMPONENTS DIFFERENTIAL HIGH LIMIT PRESSURE SWITCH LOW HIGH LIMIT LIMIT SPRINKLER CIRCUIT HEADS RETURN N.O. AIR PE SUPPLY MAIN AIR AIR FRESH AIR INTAKE 2.16
THREE-WAY VALVES MIXING VALVE DIVERTING VALVE NC C NC C NO NO Three-way valves are usually available as mixing or diverting. Mixing valves have two inputs and one output. Diverting valves have one input and two outputs. Usually there is a flow through the common port of three-way valves; however, rarely one type of three-way valve allows flow from the common port and only through either the normally open port or the normally closed port and sometimes no flow at all through the valve. The direction of flow must be correct. The spring ranges can vary from valve to valve creating different throttling ranges. The effective throttling range on valves can be adjusted if a pilot positioner (positive positioning relay) is installed on the valve. FACE & BYPASS AND WING COIL DAMPER ARRANGEMENTS ACTUATOR ACTUATOR WING FACE & COIL BYPASS DAMPER COIL DAMPER COIL BYPASS Wing coil and face & bypass damper arrangements are often used when the upstream air temperatures may fall below the freezing point The control circuit should allow the heating coil full flow before exposing the coil to air flow via the dampers. The wing coil damper arrangement allows the sections of the heating coil to be completely enclosed when no heat is required. Most often the heating coil has full flow when the outside air is below freezing. Proper safety circuits normally are installed on these systems. TWO-WAY VALVES NO NC Two-way valves are either normally open (NO) or normally closed (NC). The spring ranges can vary from valve to valve creating different throttling ranges. The effective throttling range on valves can be adjusted if a pilot positioner (positive positioning relay) is installed on the valve. The direction of flow must be correct. AUTOMATIC DAMPERS OPPOSED BLADE PARALLEL BLADE Automatic dampers are used to isolate the building systems when fans are off and blend fresh air with building return air when the fans are running. Opposed blade dampers achieve more linear flow respecting percentage open to percentage of maximum air flow than parallel blade dampers. Parallel blade dampers, if installed properly, tend to achieve better mixing of fresh air and return air than opposed blade dampers. 2.17
50 100 0 20 30 40 60 70 80 90 Air driers dry the compressed air by cooling the air to dew point and then continuing cooling to about 38°F, condensing the moisture from the air. The condensed water collects at an auto drain which relieves the water from the system either via a float mechanism or a timer with a solenoid. AIR FILTERS DELTECH PARTICLE COALESCING The orifice that feeds the “brain” of many pneumatic controls is only .005”; therefore, proper filtration is critical. Particle filters remove particles down to the rating of their elements. (usually 40 micron or 5 micron) Coalescing filters remove oil and particles. (usually down to .1 micron) Data sheets suggest replacing the element at 10 PSIG pressure drop at 10SCFM airflow. Deltech filters remove oil and particles down to 1 micron. The element is changed based on colour change in the element from white (pinkish/white) to deep red. RELIEF VALVES Relief valves are safeties preventing over-pressurization of a tank or air line. They should not be painted and should be tested regularly as part of normal maintenance. Relief valves on compressor tanks are set respecting the design operating pressure of the compressor. Often relief valves on control compressors are set at 100 PSIG. The relief valves installed after the pressure reducing valve on control systems are normally set between 23 PSIG and 30 PSIG. Sometimes the pressure relief valve is built into the pressure reducing valve. FLOW METERS Flow meters are installed indicating the quantity of compressed air passing to the control system. (standard cubic feet per hour SCFH) They alert the operator to air leaks in the system, which waste energy and burden the compressor. They are very useful in trouble shooting compressed air leaks in building systems. 2.18 NC NO AIR DRIER NO BYPASS VALVE REFRIGERATED AIR DRIER
B M 1 2 3 B M 1 B M T VAV BOX PNEUMATIC TRANSMITTERS AVERAGING BULB ROD Pneumatic transmitters sense a medium with their element and only report the condition to a gauge, receiver controller or both: they do not control. All commercial transmitters have a 3 PSIG to 15 PSIG range. A few are two pipe with relay volume capabilities, but most are low volume, one pipe using a .005”, .007” or a .0075” restrictor. The reporting characteristics may be temperature, relative humidity, pressure, enthalpy, etc., with multiple ranges in each. The indication gauges seen on the control panels are actually pressure gauges with a 3 PSIG to 15 PSIG range calibrated to indicate temperature, humidity, etc. relative to their associated transmitter. DUMP BOX (BYPASS BOX) CEILING SPACE RETURN AIR SUPPLY DUCT OCCUPIED SPACE Dump (bypass) boxes are the mechanical means of regulating the quantity of cooling air allowed into the occupied space based on the thermostat’s control of the damper actuator in the box. The fan provides a constant volume, as the supply duct always passes the same quantity of air. RECEIVER CONTROLLERS SINGLE INPUT MULTIPLE INPUT Receiver controllers receive a pneumatic signal or signals allowing the receiver controller to determine what position it should put the valve or damper to attempting to maintain the receiver controller’s set point. The proportional band determines the throttling range of the controlled valve or damper actuator. The authority determines the relationship of temperature change on the primary and secondary ports to rebalance the instrument. The control point adjustment (CPA) allows remote adjustment of the set point regarding the instrument. VAV BOX (VARIABLE AIR VOLUME) SUPPLY DUCT OCCUPIED SPACE AIRFLOW CONTROLLER VAV boxes are the mechanical means of regulating the quantity of cooling air allowed into the occupied space based on the thermostat’s control of the damper actuator in the box. The fan requires inlet vanes or variable frequency drive control (VFD) controlling the supply duct pressure as the total quantity of air required by the VAV boxes varies on thermal load changes. Systems with the airflow controller are called pressure independent and systems where the thermostat goes directly to the damper actuator are called pressure dependent. 2.19
NOTES
SECTION THREE (THERMOSTATS) -Non-relay thermostat 3.20 -Relay thermostat 3.21 -Change-over calibration board 3.22 -Calibration procedure 3.23 to 3.26 -sample of thermostat air use an leak impact on compressor 3.27 PUPOSE OF SECTION: Present understanding of range and types of thermostats and required calibration equipment.
PREFACE Proper calibration of thermostats is critical to comfort as well as proper energy control. Day/night and summer/winter thermostats are switched modes by a change in the main air pressure. There are several combinations of pressures achieving this change-over depending on the manufacturer and the particular building. Many thermostats are considered defective and replaced when the service person does not have a calibration change-over board illustrated on page 3.22. All that is required most often is an adjustment in the change-over point and recalibration of both operational modes causing the thermostat to perform as new again. On one occasion a client bought five hundred day/night thermostats to upgrade a whole high school. APS was hired to replace the thermostats with the school board’s control mechanic. Although the sealed boxes, containing the new thermostats, indicate “factory calibration”, we never trust that statement. Logically the calibration can only be accurate for one spring range and will be out of calibration for all others even if the factory calibration was done properly and the thermostat was treated gently from that point onward. On this occasion we tested three hundred thermostats for day calibration, night calibration and change-over point. Not one was accurate on all three considerations. We also found multiple other problems with the three hundred “new” thermostats. We very much advise to check every thermostat for proper calibration and operation before putting it into service, even though the box states “factory calibrated”. The signal from occupied space thermostats can control their own associated valves, VAV’s or damper motors and also be used to co-ordinate the heating and cooling provided by the base building heating and cooling equipment. The thermostats’ output signals from 0 PSIG to 20 PSIG create a ramp where functions can be selectively allowed in various segments of the ramp. This allows the system to minimize the over-lap of heating and cooling. Air leaks waste a lot of energy and may damage your compressor via extended run periods. Page 3.27 presents the impact of a thermostat signal air leak, while still maintaining enough pressure to control the temperature properly. A Johnson Control T4002 thermostat controlling a valve with a 3# to 6# range and a diaphragm leak causing the branch signal to drop from 20 PSIG to 10 PSIG will, while still maitaining temperature control, be consuming as much compressed air as 40 thermostats with no leaks. Control air compressors are normally sized to handle 25% to 33% run time: not large air leaks. i
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