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  1. #1
    Join Date
    Nov 2004
    Location
    Thibodaux, LA
    Posts
    1,170

    Pneumatic Controls

    We are taking over a three story office building with a parallel air cooled chiller setup on the roof. 2 (30GT---50). They have a central fan on each floor and use the ceiling as the RA.

    Each zone uses a Redd 1 fan box with 2.5kw electric heat. All the controls are pneumatic. The building is about 10 years old.

    I started researching the building the other day. We are in the process of getting all plans and maintenance records.


    Where can we go to get some training on pneumatics?

    I found a couple air leaks. How reliable are pneumatic controls?

    What kind of maintenance is needed and how often?

    What can we expect to fail?

    Seems to me any type of digital control system would have been much more reliable and easier to monitor.

    This is a manufacturing plant we have been providing service to for about 20 years. This was the only building on the property we did not maintain. They have been asking for a couple years for us to take the building over and I finally gave in.
    "Football Season again finally"

  2. #2
    Join Date
    Dec 2006
    Location
    Hartford, Connecticut
    Posts
    442
    In its day Pneumatic Controls were good, however most new work is usually DDC, but not all. Many building have installed DDC as an overlay keeping the pneumatic end devices.

    Pneumatics are very labor intensive. Air leaks can be tough if they are hidden or behind walls. Ultrasonic testing works well. To keep a clean dry system and calibrated devices requires frequent intervals and a fair amount of time depending on the size of the building.

    You have many options.
    1. Have someone experienced at least calibrate the main controllers & stats to get you by until you are ready to do something.
    2. Contact some local reps for DDC systems and get some ideas, proposals and pricing for a retrofit. If full DDC is too expensive maybe leave your end devices for now if they are in good shape. It is difficult to make solid recommendations without seeing the building.
    3. Contact your local electric utility company to see what rebates or incentives are available to retrofit from pneumatic to DDC. Your local utility rep will probably be interested so they have the building do setback, temperature reset, load shedding/demand limiting etc...
    4. You should probably do a thorough building audit. You may have old inefficient equipment that can be part of a more comprehensive energy project that would include new controls.

    There are places that still do pneumatic training. Seems like allot of money to invest. I would wait a little bit to see if you are keeping the pneumatics around for awhile, I would rather invest in DDC training down the road if you go that route.


    http://www.tempconinc.com/

    http://www.nokti.com/

    http://www.pneuline.com/

    http://www.yorkland.net/register.cgi

    http://www.sbt.siemens.com/hvp/staefa/training/hvac.asp

    [URL="http://www.johnsoncontrols.com/publish/us/en/products/building_efficiency/johnson_controls_institute0/courses/search_for_a_course0.html"]

  3. #3
    Join Date
    Jun 2008
    Location
    CA
    Posts
    46

    Pneumatics

    Are easy to understand. They are similar to DDC in that there are hi,lo, reversing and many other types of pneumatic modules. The difference is the pneumatics are pieces of hardware not software modules that can be adjusted and tuned for optimum operation.

    Air leaks are like PIDs that are not tuned. You have hunt or sloppy control.

    If you understand electricity, voltage and current and understand the various software operators available in DDC then you should have no problem understanding pneumatics. Air pressure and volumne.

    And if operational money were no object I would prefer to use DDC to pneumatic transducers to operate my end devices such as valves and dampers. But alas those days are over.

    Been there done that.

  4. #4
    Join Date
    Jan 2003
    Location
    USA
    Posts
    1,670
    I went to this class many moons ago and thought he put on a real good class.

    You will get a lot of what you need training on.

    He focuses on calibrating and basic system operation. Should be plenty to keep you busy in that building.


    http://www.bochvac.com/page2.htm

    Air leaks, water & oil = big problems!

  5. #5
    Join Date
    Nov 2001
    Location
    Seattle, WA
    Posts
    7,757
    Create a log in to this Honeywell site and you should just about get everything you need for control theory.

    http://www.buildingcontrolworkbench....e=Gctrltoc.htm

    I'd keep the pneumatic controls, as long as they are in good shape, for as long as possible. Pneumatic controls were around long before DDC controls and have the benefit of being maintained, repaired and replaced by you, the guy in the field. I have buildings that are still operating with pneumatic controls that are over 40 years old. A lot of the original controls are still in place and working just like new.

    DDC controls certainly have their advantage as to preprogramming events and schedules. The draw back is that the companies that design, install and sell these systems tend to hook the customer into them when it comes to software, servicing and the good old "obsolete" or "update" process that cost their customers a fortune.

    I've removed a few small DDC controls and replaced them back to pneumatics. The customer costs and headaches were reduced greatly.

    They last a long time, you may get an air leak from time to time but it's not a big deal at all and the most improtanat part of maintenance is making sure the air is clean.

    I have a school system that I have taken care of for years. Two of the buildings have 20 year plus Honeywell pneumatic controls. I get called there about every 2 to 3 years just to go over the two buildings. I've replaced a couple of thermostats and have done some small repairs/replacements. The main cost to this school system is me driving there as it's about 100 miles away.

    Their high school, which is fairly new, if DDC controls. These controls, according to the physical plant manager are constantly under repair and/or failing almost since new. And the cost to get a tech over there and spend a few days in repairing the systems has been astronomical.

    BTW, a new and younger school board has been voted in and the last time I talked to the plant manager they are going out for bids for replacement of all the existing pneumatic controls in a conversion to DDC. Why, because it's the latest and greatest thing. This is the type of thinking that drives up the costs of public education.
    "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

  6. #6
    Join Date
    Dec 2006
    Location
    Hartford, Connecticut
    Posts
    442
    DeltaT,

    I respect your comments, however I strongly disagree. I started with and still work with pneumatics. I gladly provide pneumatic service for those needing it and will still install it.

    For me it is about running a building more efficient and smarter. I do not have all night to list the advantages but let’s start with this;

    DDC:
    Network (LAN) to share global data.
    Custom algorithms and programming.
    Alarm notification / dispatching.
    Remote access (phone line or web access).
    Trending capability.
    Optimal Start/Stop
    CO2 / DCV.
    Demand limiting.
    Integration to Access Control, Security/Intrusion, Lighting Control.

    Pneumatics:
    Yes they work well, but I have seen nightmares. I had a middle school last year that spent $ 15,000 to clean up a mess. Oil and water contamination, bad compressors, bad t-stats.

    All controls (pneumatic and DDC) are only as good as the engineering, installation, setup, checkout and maintenance.

    I have seen DDC nightmares too. Usually it is the wrong controller, field device or program for a certain application. Also poor installations, and systems that were left in auto pilot with no maintenance.

    If this particular person can find a reputable controls contractor with a decent open system who can provide a cost effective DDC system, I think they should go that route.

    I feel your pain. With school systems in particular they are cut throat plan and spec jobs. Many contractors take them at very low margins and get in and get out. Often times the system installation is incomplete, programming or sequence of operations is not correct or it is not commissioned. By the same token many districts have custodians or a HVAC tech that is not properly trained with that DDC system running the building. Many times the building operators have insufficient training. So it’s easy to see why school projects get hosed up.

  7. #7
    Join Date
    Nov 2001
    Location
    Seattle, WA
    Posts
    7,757
    twisted
    You & I actually agree. The main problem I have always had with the majority of DDC contractors that I have to work with is not necessary the controls, since a control is a control is a control, but the way in which they do business plus hook the customer into becoming dependent on them and/or the DDC control manufacturers.

    In the 70's I designed and sold energy management systems to commmercial buildings in the Washington DC area for Honeywell. Before that I was an application engineer for Johnson Controls in the early 60's when electronic controls first were invented.

    I was deeply into electronic controls on the onset of this new field. Then I continued into DDC controls dealing with the first R to P control sensors from the 70's, which overcame line resistance and voltage drops.

    Then the personal PC became pratical and anyone who could write software got into HVAC as a money producing field. Control theory went to hell in a handbasket from that point on.

    As one very small example; I have an old Maryland friend, who now has his own chruch, contact me about HVAC problems. The building is 3 years old and the DDC control contractor talked him and the board into installing a new and better DDC control system at a cost of over $100K. Then, with the new controls the chillers were running 24 hours a day along with the propane fired boiler to control humidity in his building. The chillers are failing, of course, the humidity issue has not been solved and his utility costs are literly breaking the church in half.

    All that was needed in his building was a stand alone dehumidifier system, which would have cost far less than the thousands and thousands of dollars and damage his building has now cost.

    Previous to contacting me, we are 3,000 mile away, he contact other control people and their answers to his problems were to always remove his particular control manufacctures controls and replace them with their brand.

    Most, I have found, are in the control selling business and not in the HVAC business.

    And, no, this is not an issolated incident.
    "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

  8. #8
    Join Date
    Dec 2006
    Location
    Hartford, Connecticut
    Posts
    442
    Agreed. Unfortunately there are ethical contractors and not so ethical contractors in every trade. I guess the customers and end users need to do some due diligence before doing business with a controls contractor.

    They are taking a chance, no different than with a mechanical contractor or HVAC service company. The difference is they can call many qualified ethical contractors to service their HVAC equipment without the need to “rip it out”. With DDC, few competitors will service a system they do not rep and they should not if they are not authorized and trained. Hopefully there is someone else in the area that can provide service.

    I hear you loud and clear. I am off to a hospital in the morning to make good on one of my jobs that did not go so well.

  9. #9
    Join Date
    Jul 2001
    Location
    Canada
    Posts
    1,810
    DELTA T and TWISTED PAIR you both posted valid points / info

    Have many older pneumatic systems that I look after of all MAJOR manufacturers from the 50's & 60's , they serve the needs of the customers and with good service they work fine. Like to see a 40 year old DDC system that could still be 90% original .

    Have added DDC to quite a few leaving the pneumatic end devices , and also completely gutted the pneumatics and went DDC / electronic for everything.

    Just finished a large system 4987 points that has a COMPLETE PNEUMATIC Backup as they do not trust the DDC to never fail ( GOVERMENT so $ no problem )

  10. #10
    Join Date
    Jun 2001
    Location
    San Diego, CA
    Posts
    1,149
    Pneumatics are fun fun fun. There's really only three things you need to know. First - 7.5 is your happy spot. Below 7.5psi, something happens and above 7.5psi something else happens. Second - the difference between direct acting and reverse acting. And third - where to get all those funny looking devices.

  11. #11
    Join Date
    Sep 2006
    Location
    Alaska
    Posts
    459

    Pneumatics

    I agree with Twisted Pair, make sure you have dry clean air. To achieve clean dry air make sure the refrigerated air dryer is installed and working properly. Make sure the air filter stations have new filters and install new inline filters at each controller. I would install an automatic drain on the air compressor tank. Then I would usually compare the drawings to the control system and reverse engineer the components by tracing out each controller. Finally once you have a good idea of what each part does, you can calibrate the system.
    Law Of The Thermostat: He who has the thermostat wins!!!!!

  12. #12
    Join Date
    Dec 2005
    Posts
    107
    The pnuematic controls on the Reddi boxes are likely made by KMC.
    They are very reliable, inexpensive and easy to use.
    They really should be recalibrated every 5 years for best results.
    Common lifespan is 20-30 years before replacement.
    The most important thing is that you must have clean dry main air at a minimum of 20 psi (22 is better).
    Very good instructions for setup and adjustment of pnuematic controls are available from Titus and Price (other fan box maunfacturers).

  13. #13
    Join Date
    Nov 2004
    Location
    Thibodaux, LA
    Posts
    1,170
    Thanks guys for all the great advice.

    We are in a climate where little heating is needed. The Reddi fan boxes have 2.5 kw of electric heat installed in each zone. Which on average consist of 2 to 3 offices.

    I did notice on alot of the wall controls on the third floor the dials were turned all the way clockwise. Many of the fan boxes with the heat elements were running.

    I also noticed the damper controls to be very slow to react and then to move is this normal?

    I want to look more into the heaters running because after talking to a few of the occupants it was noted that many of the heaters run often. Seems very inefficent. I thought raising the water temperature a couple degrees would help compensate. The chilled water system is currently set at 42 degrees F. I am considering raising it to see what happens.

    I may have to get someone in to help with the controls because the previous company was there servicing the system constantly. When walking though the building one can feel many temperature changes.
    "Football Season again finally"

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