HVAC Tech School: How to Calibrate 4 Different Brands of Pneumatic Thermostats in 5 min or less

[@joeguilfoyle1922]

I just started a new job as a building maintenance engineer for 2 buildings that have a pneumatic HVAC system and i'm learning from scratch. This video was very helpful. I was told today that our bldg ideal pressure for the thermostats is 9 psi. Your explanation as to why made since to me and it our actuators look exactly like the ones you showed. I can't remember excatly why he said it was 9 psi, but I think it had something to do with the outside air pressure and the inside air pressure. I'll ask my boss to explain it again to me tomorrow. Thank you. This was a great video for guys like me. Now I just need the Johnson's adjustment screwdriver. I have 2 Honeywell but no Johnson's :-) We use both in our bldgs.

[@barrywitt1661]

The 9 psi is related to the pressure at which the chilled water valve and the Hydronic heating water valve actuator activate. The direct acting chilled water valve actuator usually begins to open at 11-12 psi and is fully open at 20 psi. The reverse acting hot water valve actuator typically begins to open around 8 psi and is fully open at 0 psi. At 9 or 10 psi neither valve is open and no cooling or heating is being called for. You should be dialing your Tstat setpoint to match the room temperature which would be no call for cool or heat and then calibrate your tstat air signal output to the no call 9-10 psi range. As the room temp goes up the tstat will send a higher pressure to open the chilled water valve. As the temperature falls, the tstat will send a lower pressure to activate the hydronic heating water valve.

[@user-ff9ms7uh8h]

I've watched a few different training videos regarding calibrating stats. I would add the importance of remembering the fact that the heat from our hands will affect the t-stat reading during calibration. We need to try and minimize handling the stat during calibration.

[@garydelgado3077]

Last stat you didn’t show branch test port

[@brittwarren6022]

Where can I get the johnson controls adaptor?

[@3131Bubba1313]

Good to know about tweaking of the T4002. I would dump the air out of the thermostat and let it rebuild the charge, then see where it stops. I swear every time I stare at it it’ll change the pressure dramatically.

[@EricStromquist]

They can be very sensitive, glad the video was useful. Quick question, I am trying to figure out how my controls disrtribution business can be more useful to the industry. What is your biggest challenge in business in 2019? What is the best thing a supplier has ever done to earn your loyalty? If you have a second to answer these questions it would be very hellpful. Thnaks.

[@richh9904]

breathing on the BI metal.

[@alexperalez997]

I have been having problems with my actuators and i don't know what else to do

[@attacknblack1984]

Good stuff

[@nramos137]

how did you caibrate the last stat if you didnt plug in the pressure gauge to it? or did i miss something?

[@jbouldin3]

nramos137 You are right. He didn't show much on the Robertshaw thermostat.

[@chadpreston5549]

His guage was hooked to poly that was attaches to branch or the valve. It doesn't have a pressure port as others. Its out (stats branch) is where u measure YOUR STROKE. not everything gets set to 10.5. This guy is EXCELLENT! #knowyourstroke lol

[@homboga]

My whole purpose of watching this video was to watch the last t-stat; Robert Shaw or Schneider.

[@joeguilfoyle1922]

Was wondering the same thing. Since we didn't have a great view, I was wondering if that stat had it's own built in gauge. I couldn't tell.

[@cgsauro]

the top right corner there's a hole where you can add your gauge.

[@EricStromquist]

[@robertlyons692]

how to calibrate the Johnson T-4502 thermstat

[@robertlyons692]

how to calibrate the T-4502 thermastat

[@geraldschilli8870]

These procedures are fine if your t-stat feeds directly to an actuator, but not if your t-stat feeds a velocity controller on a typical v.a.v. box.

[@therandomchannel6103]

Where can I find that adapter for the gauge you used on the t-4002

[@techniquechem2957]

the adapter JC-5312, the meter G-2010-5 by johnson controls

[@ronaldsantos7078]

what is the purpose of calibrating the stat? Does it position the actuator mid stroke which position the damper 50%?

[@jacintotorres1649]

Yes