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Thread: T991A

  1. #1
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    Feb 2005
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    T991A

    Does anyone know of an electronic or digital version of the T991A Honeywell proportional controller?

    Thanks.
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2.
    My competition are my best salespeople!

  2. #2
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    If you need to stay with the resistance control, Kele makes a good universal resistance transducer model# RES-1E that we use on our boilers to control burner modulation with our BAS. With this you can use any temp. control with a modulating signal.

  3. #3
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    Quote Originally Posted by local 392 View Post
    If you need to stay with the resistance control, Kele makes a good universal resistance transducer model# RES-1E that we use on our boilers to control burner modulation with our BAS. With this you can use any temp. control with a modulating signal.
    Thanks for the information. I've been looking it over. It would definitely do the job.

    I have just found the Neptronics KI135 version of it on-line and will get both priced out. I can use either with a Johnson A350PS-1C controller.

    I could replace the old T991A but they are ridiculous expensive for lousy (inaccurate) temp control. Going electronic I hope to get better proportional control.

    It is a simple make-up air and if I can get away without having to replace the actuator I will.
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2.
    My competition are my best salespeople!

  4. #4
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    Jun 2008
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    Windsor, Ont.
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    Honeywell T775 (modulating) will work with it as long as it's an M91xx series motor your driving.

    http://customer.honeywell.com/techli...0s/63-1318.pdf

  5. #5
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    Quote Originally Posted by nyrb View Post
    Honeywell T775 (modulating) will work with it as long as it's an M91xx series motor your driving.

    http://customer.honeywell.com/techli...0s/63-1318.pdf
    Thanks for the answer, but is a M91xx, specifically series 90 proportioning control, the same as a M94xx proportional flame safeguard firing rate motor? I just noted the difference here, Honeywell's page 1...

    http://customer.honeywell.com/techli...0s/63-2691.pdf

    I just can't find enough lit to confirm or deny the T775 will work with the M9484F4001 actuator. I have to prove low fire before the burner motor will start. So that means an upfront r-y (R-W) drive close for the end switch to start the burner motor. By shorting r-y could that damage the T775? I may have to leave compatibility in the hands of our neighbourhood WWG.
    Last edited by gruntly; 02-12-2010 at 12:01 PM.
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2.
    My competition are my best salespeople!

  6. #6
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    Jan 2008
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    Dallas ,Texas
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    Is it a gas valve your trying to control ? Possibly a V9055? Nevermind I just read where you said actuator. Go to honeywell`s website and email them your question using the contact us feature. They will email you back some correct info. I have done this and the local guy said it would work but Honeywell sent me bulletins saying it would not. Your answer might not come quick.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  7. #7
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    New Jersey
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    Why not use a Honeywell Q7230A to convert the actuator to 2-10vdc. Then you can use that Johnson A350PS-1C. Then to drive low fire you just need to open the circuit, instead of jumping R and W like you were.

  8. #8
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    Quote Originally Posted by gruntly View Post
    Thanks for the answer, but is a M91xx, specifically series 90 proportioning control, the same as a M94xx proportional flame safeguard firing rate motor? I just noted the difference here, Honeywell's page 1...

    http://customer.honeywell.com/techli...0s/63-2691.pdf

    I just can't find enough lit to confirm or deny the T775 will work with the M9484F4001 actuator. I have to prove low fire before the burner motor will start. So that means an upfront r-y (R-W) drive close for the end switch to start the burner motor. By shorting r-y could that damage the T775? I may have to leave compatibility in the hands of our neighbourhood WWG.
    Yes the T775 will drive that motor with no issues, it won't drive the old generation of mod motors that are still kicking around on some pretty old equipment. As far as the low fire position goes switch the 'R' wire through a SPDT set of contacts so that R-W(modmotor) is shorted until ignition is completed and then R(controller)-R(modmotor) will release to modulate.

  9. #9
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    Well, thanks for all the replies. Good advice here.

    Looks like it's gonna be a T775M2003 to drive the M9484F4001 firing motor and continue to use the existing low-fire proving relay/end switch because it breaks the "R" controller and closes "R to W" motor until the firing end switch closes, allowing ignition to start, as mentioned above.

    Apparently, I won't need the internal controller switches, hence the M2003, because the existing low-fire proving shouldn't damage or interfere with the new controller (hopefully). The main actuator/valve has it's own POC set-up and doesn't play into the firing/modulating system at all.

    The price is much better for the T775 than a T991 anyway and much easier to install (sensor & controller) in a useful place.

    Thanks for the help. I'll let you know how it goes.
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2.
    My competition are my best salespeople!

  10. #10
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    Jun 2008
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    Windsor, Ont.
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    Good luck with the job and don't do what I did on my first one and forget the little resistor you need (its included in the package) as per page 8.

    http://customer.honeywell.com/techli...0s/62-0254.pdf

  11. #11
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    Jun 2004
    Location
    St Paul, minnesota
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    Hmm

    I recently installed a T775M2048 in a direct fired MUA. It replaced a T991 (T991 was replaced 2x in 1 year). this was for a paint booth. the T991 was inside the MUA. If they needed to change the set point they had to go to the roof. it did have a room override which drove the firing rate motor to 100% for paint curing. I installed the T775 next to the summer winter switch, which the customer really appreciated. I had to set the dead band at 20 degrees to keep the valve from hunting. I used sensor "A" for the discharge air and sensor"B" for the room override. works very well.

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