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  1. #1
    Join Date
    Oct 2010
    Upper Midwest
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    Pneumatic T-Stat

    Hello everyone! I'm working in a building warehouse pneumatics and controls from the 60's. Giant units. Borg-Warner units with 25hp motors and such. No pneumatic schematics. The rumor is all of the building engineers shredded them when they went on strike and knew there were layoffs coming.

    A problem I'm having is that I don't know what the equivalent is of this two pipe tstat I need to replace. It's got no numbers, letters, markings I can see. All I know is that it's a direct acting tstat. It goes to a receiver/controller and then to the heating valve (N.O) and cooling valve (NC). A typical set up. The warehouse was really warm and the tstat was leaking air, so full on heat. (Verified and positive)

    There seems to be a bigger screw adjustment on the top, probably for temp adjustment. I had my pressure gauge on it and turned the screw but it didn't change the pressure going to the receiver controller. Right now I have 20# going to the receiver/controller to keep the heat off. It kinda looks like there's a part from the tstat missing. Maybe the temp adjustment is gone so people don't mess with it. Not too sure. A Minnesota winter is coming so the heat will be needed. Right now the building has enough heat to keep it warm.

    Anyways, is there something I'm missing? Something different with the internals? Pneumatics was barely covered at school 12 years ago. They're kinds of receiver controllers I have never seen before. Lol. I tried another tstat that we've got tons of in this building but it didn't work this time. Any tips on finding pneumatic tstats? Grainger is kinda useless....
    I have a picture of it but it won't load right now. Maybe later I'll try.

    P.S: (The chiller is off) and the tstat I tried was a Barber Colman Tk-1001-0-2.
    Last edited by Big_Ern; 11-01-2018 at 02:22 PM. Reason: Information

  2. #2
    Join Date
    Aug 2016
    San Diego
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    What brand is the T stat? I know Grainger sells Siemens, JCI, and Honeywell Pneumatic t stats because thats where we get them from. I dont care for Grainger but they do seem to have these in stock where most of the supply houses wont carry them
    The link is to Grainger's section for pneumatic t stats. They actually have an entire pneumatic controls section with most anything you could need. Except diaphragms because we literally bought all of them in the US at one point and had to order from europe to get some spares.

    Edit: Missed the part about the brand. But that shouldnt matter. If you get the siemens T stat Grainger # 4E668 or 4E669 for DA and RA respectively you can mount it just about anywhere. Ive replaced a bunch of different brands with that one because its one of the better ones and it comes with a bunch of mounting hardware and fittings.

    Good luck!

  3. #3
    Join Date
    Oct 2011
    Chicagoland Area
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    Honeywell, JCI, and Powers all sell retrofit kits so, it doesn't matter much what brand is currently being used. Just match up the parameters
    Officially, Down for the count


    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  4. #4
    Join Date
    Nov 2011
    East Side
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    If you post some pics of what you have, we’ll be able to identify them.

    So you have 20 psi to the stat, then the stat is sending a proportional output the controller, then the controller is sending s proportional output to the valve? Does the controller have another input, other than the stat?

  5. #5
    Join Date
    Apr 2018
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    From what I understand your 2 tubing tstat: one main air come in and one branch out to control. Find out pressure ranges on your heating and cooling valves to calibrate them to open or close accordingly to change in temperature on tstat. DA tstat builds more pressure on branch when space temp raise.

  6. #6
    Join Date
    May 2014
    Bay Area California
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    As has been said. Any 2 pipe pneumatic stat will do; I'm guessing you are talking about a wall mounted stat used for space conditioning. Just set the throttling range, then calibrate to whatever pressure you want at setpoint; TR needs to be set first.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

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