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  1. #1
    Join Date
    Jan 2005
    A control forum without a mention of Pneumatics, working in the northeast there is still a fair amount left out in the field. I have installed about 15 straight pneumatic systems in the past year(mainly due to the problems of ddc systems prior). no call backs...... I get my night setback/econimizer lockouts/ enthalpy control/s/w mixing boxes with min.position.....without the worry of a powerfalure or corrupt file. Its not that a "properly intalled ddc system that is maintained" isnt the way of the future but I think its overkill in some instance. Just wanted to give my 2 cents from and old pneumatic conrol guy :>

  2. #2
    Join Date
    Sep 2002
    nothing wrong with pneumatics its just replacement parts are getting more expensive and harder to find. I just recently bought a honeywell transmitter and it was 400 bucks!

  3. #3
    Join Date
    Dec 2001
    I have an account with 1 powers outdoor air transmitter, 2 pressure receiver controllers and 2 receiver controllers for hot water reset. These are early '60s vintage stainless steel parts with a gasket around the cover.

    all these years if someone took the covers off they put them back on. They look brand new on inside i bilieve they are system 200.

    had one fail around 13 to 14 months ago and replaced it with a traditional receiver controller (talk about interoperability).

    next time i go to job i will take pic of these and post they are truely a work of art.


  4. #4
    Join Date
    May 2002
    Baton Rouge, Louisiana
    98% of our jobs have pneumatics on them, 2%ddc, thats why I like automated controls so much alot of headroom, not saying that the pneumatic systems havent done their job
    Quote Originally Posted by MatrixTransform View Post
    very soon it is you that will be pwned

  5. #5
    Join Date
    Oct 2003
    Originally posted by nytech
    A control forum without a mention of Pneumatics, working in the northeast there is still a fair amount left out in the field. I have installed about 15 straight pneumatic systems in the past year(mainly due to the problems of ddc systems prior). no call backs...... I get my night setback/econimizer lockouts/ enthalpy control/s/w mixing boxes with min.position.....without the worry of a powerfalure or corrupt file. Its not that a "properly intalled ddc system that is maintained" isnt the way of the future but I think its overkill in some instance. Just wanted to give my 2 cents from and old pneumatic conrol guy :>
    Chuckle, I wouldn't use that line about being an "old pneumatic control guy" too often. A LOT of us are old pneumatic control guys. And, in fact, a lot of those who pressed for and were in on the first uses of DDC, and who have been working the bugs out of using DDC in the field ... are old pneumatic controls guys.

    DDC has been around for quite a few years. That is not to say it has worked worth a damn for all those years. But it's been around. Trust me, I have myself, and know others who have in the past expressed their opinions about electronic and digital controls of years past by breaking out the wire cutters and performing the not-so delicate surgery called a DDC-ectomy.

    IMHO, for many years the use of DDC was pushed and promoted by a lot eggheads and computer geeks who thought they knew the better solutions. And the field saw a lot of stuff that was horrifically expensive and worked only sort-of, and required a staff of highly trainned specialists with a truck load of instruments to troubleshoot and adjust/repair.

    But then, gradually, as more folks entered the field, and prices came down, and more and more "old pneumatics guys" with real world experience in controlling buildings and equipment got involved and started learning the new methods of controls. And started giving the eggheads and computer geeks real world feedback in what they were doing right, what they were doing wrong, explaining why this or that technique wasn't gonna work or wasn't adequate in some way, and so forth. THEN ... DDC started to take off and become something more useful. In the real world.

    This is still going on. All the time we, I and others at the company for whom I work, write up technical feedback reports to the manufacturers of equipment we use telling em that this or that idea they have as to how something should work, sucks. And outline why it sucks, then offer explaination of how it should work to be more useable.

    And the manufacturers do listen. The good ones do, anyway. Not to every ***** and gripe. If one listened to every ***** and gripe, you'd never have time to get anything done. And you'd have to be making major mods to software, firmware, and hardware at least weekly. Not good.

    But routinely we see a manufacturer, after they've bench tested some precise scenario and conditions we've given em, testing first by using their previous control methodology, then by using our suggested fix, come out with a revision incorporating our idea. Or a solution of their own which accomplishes the change we suggested in another way. Or they come out with a change as a result of what somebody else gave em feedback on.

    Sometimes we even get queried by the manufacturers first. We've gotten calls where a manufacturer's rep has said words to the effect, "Hey, in such and such an application using our Model XYZ controller, we are getting a lot of calls from the field saying it doesn't work right. But you guys say you're using it that way and not having problems. How are you doing it? What fixes, changes, settings etc are you using to get it done?"

    It's a learning experience.

    Not just a lot different than when I was in the Navy and they started doing getting serious about doing a fleet-wide conversion to pneumatic ABC controls. Automatic Boiler Combustion controls. And I found myself in a classroom studying the methodoligies and theories of Hagen and Bailey (the two major equipment suppliers the Navy was using)pneumatic controls. And found self trying to learn the formulas and math to figure out the proper adjustment for some danged thing they were calling a "ratio totalizer", in a given application. I can remember having to go to the base exchange and buying a bottle of 1000 aspirin tablets because my head hurt trying to learn what was, for me, totally new concepts.

    But, I did learn. So did many others.

    DDC is no different. Anyone who can learn to truly understand pneumatics, can learn DDC. It just might require some studying, time, and a big bottle of aspirin.
    What needs to be done, what the mechanical equipment needs to do ... is the same. And you know that part. The only difference is how yah tell the equipment what to do.

    Now, there isn't a durned thing wrong with pneumatics. Installed and adjusted properly, works fine and lasts a long time. Good stuff. Very reliable. And can be very accurate. And you can do a lot of ... most of ... the things with pneumatics that can be done with DDC.

    But ....

    Lets look at a few things.

    Recently we did a retrofit of an existing building. 34 air handlers, couple hundred VAV's with reheat, peripheral and entryway radiation, assorted this and that. Was pneumatic controlled.

    BTW, the in-house maintenance crew for building owner moaned when they found out we were installing DDC. Bunch of old hands, who'd worked there for some time, plus had worked at a number of other places. Here and there several had had their experiences with DDC, and weren't impressed.

    As one guy, the maintenance sup, told me, "Why? Pneumatics works fine."

    Uh huh.

    Oh, it does. IF it's properly maintained and adjusted.

    As he was to find out, it's not always properly maintained and adjusted. He started to find that out as my guys started giving me feedback on what they found as the ripped out the old and installed the new. Feedback I summed up in reports and fed back to him.

    The total of all the problems we uncovered made for a rather thick report.

    It was a full range of issues. VAV's whose dampers were not working and had not been working for a long time. VAV's whose reheat controls did not work and somebody had either completely shut manual valves. Or had set a permanent flow rate controlled by throttled manual valve. Outside air intakes ... that didn't do that. Exhaust fans that didn't exhaust. Ceiling mounted AHU, 25 foot up over a gym which had no drive belt. Another AHU which at some time in the past had been jury rigged with new motor, pulley and belt. Which, coupled with a VERY dirty and clogged face on the coil, was outputting only 1/4 of it's rated air flow. Numerous heating coils in reheats, unit heaters, radiation, and so forth which worked ... sorta ... but which were clogged and struggling to do their job.

    So forth and so on.

    The fellow was fairly amazed at the lenght of the list. Yep, he knew he had problems. Who doesn't? It's a sizeable building, with a lot of occupants. And like everyone, he doesn't have as many on his work crew as he'd like to have and thought he needed. They were always behind, with lots to do. But he'd not suspected to see a list that long.

    Part of it is, sometimes folks just don't notice.

    i.e. AHU with OA damper that didn't work. From machinery room you could see damper actuator move, connecting rods moved, etc. But inside the intake box connection was broken.

    AHU with no belt? Motor and pulleys on opposite side from where filters were changed. Unit high in the overhead. Guy working on lift heard motor running. Hit disconnect. Lifted up, changed filters. Came down, turned unit on, heard motor, thought everything was fine. Occupants of area served at some time in the past, feeling stuffy, started up the habit of leaving doors flung open to other areas of building. That, coupled with the fact that an exhaust fan in their area had inoperable controls and remained permanently on 24/7 created enough cross flow that while they felt area wasn't right, it wasn't bad enough for them to complain.

    Items where things "sorta worked" but needed repair? In many cases occupants of office or area made comments to me later. "Hey ... something is different. On cold days I've always had to wear a sweater in here. As it was just a little cool." Or, "Geez, it was always hot in here on winter days when they had the boilers running, but I thought it was supposed to be that way." Or as one gal commented, as she raised nose and sniffed air, "What did you guys do? It was always a bit stuffy and stale in here and you could smell it if somebody hadn't changed their socks in a few days. The air is definitely fresher now." And so forth.

    Some items on the list I gave him were discovered in the conversion. Others were discovered during our shake-down, testing and commissioning phase. As we sat at front end and could SEE valve opening in a reheat, and SEE that discharge temp either did not increase, or increased painfully slowly and not enough. Or we saw damper ordered open but reading air flow measuring station we saw that we were not bringing in nearly the expected amount of fresh air. Or saw that supply fan was not moving rated CFM. Or etc, etc, etc.

    This was one of those mixed refits. Where in some cases we replaced pneumatic actuators and in others still used them. Replaced major valves but kept a lot of the existing smaller ones, etc. So in many cases, problems not noticed til we fired everything up. But now, as we did have sensors hooked up everywhere and DDC system could SEE actual air flow, detect real water flow, temp increase or temp decrease, measure amps in a motor, and so forth. We started to find a LOT of issues.

    The thing is, pneumatics work fine. BUT ...

    That buildings maintenance supervisor simply didn't have the staff to be able to routinely test and check everything. They always had their hands full just keeping up with service demands. Takes a long time to go room to room and check real temp against what controls think it is. To manually read temp rise across a coil to see if reheat is working right. To open box and crawl inside and check dampers to that when yah THINK you've got 30%, you KNOW you've got 30%. Etc.

    That's one of the major issues with pneumatics. Having positive feedback and accurate data. Without having to resort to a lot of manpower intensive, time intensive running around with hand instruments and testing control after control. In a building that might have hundreds, maybe thousands, of controls. In many cases yah have to wait for something to go so drastically wrong that space occupants get really pissed and complain.

    That building maintenace supervisor was a Doubting Thomas. Nowadays, he's a fan of the new system. Recently I dropped by to check on the installation. And he was a happy man. He comes in early on purpose and sits at his headend screen and checks stuff out. Often noting problems before occupants arrive. And regularly having problem fixed before they get there. Or, if not fixed, he greets em, tells em of problem, says he has it under control, new part on the way. Please be patient. Couple hours and everything will work right. This pleases occupants. Happy occupants means happier building maintenance supervisor.

    His guys are also spending a whole lot less time troubleshooting what a problem is caused by. Low room temp? Can see if discharge temp of VAV is rising when valve opens, can see if VAV has air flow, can see if HW converter is putting out rated temp, can see if pump is running, what pressure it's producing, etc. In a minute or two. Old way, would take em longer than that just to walk to cold room and lay hand on reheat coil to see if it's warming up. Since they spend less time troubleshooting, they have more time to be fixing, and more time to answer calls for a cleanup because somebody just spilled something or barfed in a hallway.

    BTW, his building is now using significantly less energy to maintain temps than it used to. And he's really, really impressed with the special dehumidification subroutine we put in that helps clear building of excess humidity on those difficult days. In certain kinds of weather, excess interior humidity was causing him fits. Not just occupant complaints but damage to building, fixtures and furnishings.

    Side benefit to us? <G> When I overwhelmed him with a list his guys could not possibly manage to clear up of discrepencies, he got building owner to foot the bill for a couple of our service guys to show up and lend a hand.

    Recently he did tell me there is one feature he's not too fond of. That's when his text message pager went off at oh-dark-thirty in the morning. And he found out it was his building calling him and telling him, "Help !!! Come fix me. Air handler #26 won't start and room NN is too cold." He appreciated fact that he was able to go in and replace a fuse before any major damage occurred. But, OTOH, he wasn't too happy to have to get up at that hour and go crawl into his truck at 15 below, on a weekend. Back in the "old days" when he had only pneumatics, he'd have had his hands full Monday morning. But he'd have gotten a nice nights sleep and not have had to get woke up by a "damned computer".

  6. #6
    Join Date
    Jul 2001
    Still lots of Pneumatics around , I have 1 site that will be 50 years old next year and still has over 90% of the original PNEUMATICS in place.

  7. #7
    Join Date
    Jan 2004
    New Jersey

    > did we forget about PNEUMATIC>>>

    did we forget about PNEUMATIC

    Worked for Honeywell for 30+ years,26 years pnuematic I loved the air controls, however, I came to realize the breadth of the DDC controls was superior to the pnuematic.
    Having said that, I was quick to point out the fact that I
    saw my first RP908 controller in 1964 and in the time that followed, one new controller was introduced,the RP920.
    And I also was quick to point out that over that same time there were so many elec/electronic controllers introduced that some models did not even make into the next catalog.
    One of my last accounts, a school that was biult in 1945
    had uni-vents with original damper actuators. Diaphragms
    (metaphragm)were brass segments with soldered edges. These actuators still functionng. Perhaps the case could be made, that they lasted too long! it is hard to sell new, when the old wont die.
    Also, I liked the NON SPARKING aspect,if you crossed lines.
    Pnuematics do not suck they blow- and with some maintenance they keep on working.

  8. #8

    What do use use pneumatically to sense enthalpy? The only thing I have seen for that is an old Honeywell receiver controller.

    Pneumatic control systems can be good but they quickly get too complicated when people want them to perform the sequences that ddc systems perform. Simple control systems are much more reliable than complicated ones.

  9. #9
    Join Date
    Mar 2003
    ok here goes.......we have this job to calibrate old Moore pneumatic controls. these are located in labs that utilize jet fuel for some process. according to the manufacturer, trying to calibrate these controls is like hunting for dinosaurs. problem is there isnt anything else reliable enough to follow up these oldies but goodies. set up correctly, they are accurate to plus or minus 1/2 degree. takes about a day to get 'em that way though.

  10. #10
    Join Date
    Oct 2003
    Originally posted by es555

    What do use use pneumatically to sense enthalpy? The only thing I have seen for that is an old Honeywell receiver controller.

    Pneumatic control systems can be good but they quickly get too complicated when people want them to perform the sequences that ddc systems perform. Simple control systems are much more reliable than complicated ones.
    Yep. Tho, in some cases that's precisely a strenght of pneumatic systems. If your requirements aren't complicated, pneumatics serve well. Granted that your system is large enough to justify the energy expense of operating a controls air compressor.

    OTOH, DDC systems can offer their own version of simplicity. As in one job we did. 18 floor office building. A retrofit. 20 to 36 VAVs per floor, varied according to floor and office arrangement. Occupied areas.

    We had a tech preprogram each VAV controller in the shop. Giving each it's respective heating and cooling setpoints, min and max flow requirements, adjusting PID loop for heating valve control, and populating it's schedule of operation according to customer desires, complete with setback and setup values (the two not being the same number), etc. This just entailed his making a master copy of the desired setup, and then he stuffed a copy into each one. Just required a click of a mouse. Then a few keystrokes to enter, for each, it's own individual min and max airflow and it's "k" adjustment factor so it could convert velocity to a CFM reading. If he had a complaint, it was that it was very boring work. Took him only a few minutes per unit.

    Benefit was that the controllers were then delivered to the site. And as our installers installed each and wired and applied power, VAV controller came awake and went about doing it's job immediately.

    Comfort level of the occupants wasn't significantly affected as we progressed thru the job. We'd put some wire pullers to work on the night shift so for a floor all wires would already be pulled and in place. Then during the day, a couple guys would move along, working quietly. Strip out old controls, mount new and terminate. Immediately new controls in working order and doing their thing. Move on to next unit. About the only occupant disturbance being that occassionally one of my guys had to ask someone to scoot chair to side a foot or two. Or ask person to maybe take a 20 minute coffee break. Then come back and he'd be done.

    In the meantime, another guy was at front end watching. As each VAV controller came on line he'd see it. Would be talking to installer over radio quietly. Verified what he was seeing was the controller he thought it was, right office space, etc. Then as installers moved on, head end guy put VAV controller thru it's paces. Simulating high space temp, low space temp, etc. Watching and verifying controller adjusted air flow, opened and closed reheat, duct temp increased when reheat opened, and so on.

    Nice, simple job. Each floor had it's own AHU. Which were all essentially identical, operation-wise. Enough so that a common program served all, needing only a few tweaks to account for differences in CFM capacity and so forth. For each we had wire pullers do their thing first getting everything in place. Wires, conduit, and sensors. Then, we'd have adequate guys on hand. Shut unit down and zip ... zip. Everyone knew what to do. Pull old damper actuators, install new. Terminate those. DDC controllers already mounted and terminated, and pre-programmed. Cut in power to controllers, and to AHU and she was off and running. Total downtime, about 4 hours. Max. Several times wasn't even that long. We did this at night, after even late working occupants had left. This left us lots of time to test and correct any problems. Minimum disturbance of occupants, which made the property owner happy. Fast and easy, manpower wise, which made us happy.

    Preprogramming, being able to have everything set up and ready to go, ahead of time. Is a very handy thing. And being able to duplicate very precise settings and adjustments on multiple controllers with the click of a mouse button is also handy. Makes things nice and simple, for the actual installation phase of things.

    Of course, things are not always that simple.

    ie Recent job. Multi-air handler building. (22) Heat and cool coils. Economizer, with spec to have enthalpy of OA compared to enthalpy of RA, and have system decide whether or not to use regular economizer mode, OA thru energy recovery unit, or no OA at all except minimum required. Add requirement for minimum OA, to be reset by RA CO2 content. Specific requirements for a dehumidification mode. A minimum of 4 schedules that could be pre-programmed. 4 SEPARATE, individual schedules for each air handler. PLUS, ability to send master command to occupied or unoccupied mode from central location to override all individual schedules. Add requirement for manual override, to extend occupany mode, via pushbutton. One located in each zone served by each air handler. Add a requirement that each air handler was to monitor every room it served, and to go online if any 3 rooms went above or below a certain setback/setup value. Or to go online if any ONE room went above or below yet another pair of values. Constant pressure units, with VAV's. It also monitored bulding pressure in it's zone and modulated a relief damper and relief fan to control that. And just to make things interesting, design engineer specifed that if more than a certain number of rooms in each zone served by an air handler went occupied early, or stayed occupied late, as determined by occupancy sensors located in each room, the air handler was to override normal schdules and go occupied early or stay occupied later. And minimum outside air was NOT a fixed number. It was a calculated value. Determined by DDC controller based upon how many rooms indicated they were occupied. With different minimum OA CFM requirement for each room.

    Now, I'm supposing somebody could do all that with pneumatics. But I'm also betting it'd be one heck of a complicated system. And would take bloody well forever to keep calibrated and adjusted, or to troubleshoot.

    <G> No, I'm definitely not against pneumatics. Like em. Cut my eye teeth on em.

    But the fact is, customer and design engineer requirements are getting more demanding and complicated. They're expecting a lot more. Both comfort AND save energy at the same time. Plus convenience. They don't wanta have to adjust a control anymore. Want the machinery to adjust itself. And want it to predict their needs and requirements. ie The above specification and requirement where machinery watches to see how many folks are coming in early to work, or are staying late.

    Doing these sorts of things becomes tremendously complicated using mechanical control methods. With DDC, the physical work of pulling wires, mounting controllers, installing sensors and actuators is pretty much the same, whether the sequence of operation is simple or very complicated. And that part isn't exactly rocket science. Pretty basic stuff. The difference between simple and complicated is mostly a matter of programming.

    And making changes is mostly just a matter of programming. ie The other night I was at a customer's building on other business. And building maintenance supervisor complained about an issue. No big deal to fix. Actually, nothing was broken. Just a control loop that wasn't responsive enough to suit a particularly fussy and *****y occupant. I hopped on computer and redid a PID loop (just PI, actually) and adjusted a reset value. Took less than 60 seconds. Never had to break out a screwdriver or a gage, nor walk to where the controls were. That gets durned hard to do with pneumatics. <G>

    In fact, one issue we have to deal with is customers wanting "freebies". As in the above case. Customer could have made change himself. IF, he spent the time and effort to learn how. Heck, we gave him copies of every manual, all of them. Has all the info in them he needs to learn. Very, very few of our customers want to learn what it takes, tho. Probably makes their heads hurt as much as mine did when I was learning. But they soon figure out that all I, or one of my techs has got to do is a little bit of typing and we can make minor or major changes to how things operate. And we don't even have to go to the site in most cases. For most of our customers, I can do a dial in and get on their system. Which brings up a problem. Customers keep asking us to make tweaks, adjustments and changes.

    I'm liberal about it til they've signed the check. Then I give em 60 days during which I'm not gonna argue if it's something I or one of the guys can do in a few minutes. But after that, I've found you've got to play a little hardball. And I remind em that we set system up according to their specs and satisfaction, and they agreed ... after all, signed the check. Now, Mr or Mrs Customer, phone calls for my advice or to have me (or one of my guys) make an adjustment or change, is gonna cost you. And I don't bill by the minute. So it makes no difference if it only takes me 5 or 10 minutes. You get billed for an hour.

    <G> That works to keep them from nickel and diming you to death. They make a list and wait til it's long enough to be worthwhile, an honest hour or two worth of work before they call again.

    Just some thoughts on the subject.

  11. #11
    Join Date
    Jul 2001
    Pneumatic Control with Pneumatic Actuators = Kinda slow but powerful

    DDC with Electronic Actuators = FAST but slow operation

    DDC with PNEUMATIC Actuators = Fast

    At least with PNEUMATICS you can JIMMY RIG a valve or damper open , closed , 1/2 way with main air and a mini regulator kind of hard to jimmy rig 12MA's

  12. #12
    Join Date
    Feb 2004
    Here's "2 cents worth" from another old "pneumatics" guy who still works on that junk and teaches pneumatic controls seminars. You'd be surprised how many people still show up to learn basic pneumatic controls and at how many people who claim they do really don't. Still have 40 year old Powers "D" stats out in some of the schools I'm in and you can't kill 'em no matter how hard people try. Oil, water, dirt - nothing stops them. Like to see a microprocessor based controller, a.k.a. "DDC", survive even half that time in service under adverse conditions. Not likely. Pneumatic controls were the first truly "interoperable" control systems. Air is air. You could always make a Honeywell receiver controller work with Johnson temperature transmitters and a Powers valve - no BACnet or LonWorks needed here! We always had "analog" outputs available - pneumatic controls are inherently modulating and also inherently explosion proof. How much does it cost you to do an explosion proof application with DDC - $$$$$$$$$. In the way back when days "digital" controllers didn't even have analog outputs. How many of you even remember the old Butler/PTI, Paragon and Solidyne "Energy Mangement Systems" or "load controllers", just to name a few. All those controllers did was turn "loads" on and off and function as time clocks. Just goes to show you how far the market has really come.

    I love the old stuff, love to see it working the way it should, love to teach people how to make it work and keep working. But I also love the new - we work with several DDC product offerings and the stuff never ceases to amaze me. We all know what really drives DDC today - the networking and communication aspects of the products. Be in Hong Kong, get on the internet, check on your building in downtown Des Moines. How can you not be impressed by that.

    Onward and upward with the new but at least raise your glass one last time in tribute to "old man pneumatics".

  13. #13
    Join Date
    Nov 2001
    Seattle, WA
    I'm probably the only one in my area that removes DDC's and replace or re-install pnuematic controls so the customer can have value, control and longevitity.

    Don't have time to get into this but whoever previously compared lack of maintainance on pneumatic to where DDC controls need no maintenance is so full of themselves it's sick.

    I can take you to plants with faily new DDC controls that have not worked since the day they were installed. I can take you to buildings that are over 40 years old and still have the original pneumatic controls working just as well as they did when they were installed.

    Electronics are great controls. I know. I was there when we first started designing and selling them. What went wrong is when the electronic mindset got into our business. 99.5% of the DDC control people I get out of trouble or know know nothing or close to nothing about our trade.

    They sell, make promises they can't keep, tell things they can't perform on, make the customer a slave of their built in crap and then, when all else fails - cause the systems are problem prone, sell the same customer, successfully, another new DDC system. Amazing.
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

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