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  1. #1
    Join Date
    Feb 2004
    Location
    Brooklyn, NY Occupation: HVAC Service Contractor
    Posts
    258
    I service and maintain an old Liskey Aire 45 ton water cooled VAV unit. It has a Honeywell W7100 discharge air controller with six stages of cooling. Cool 1,2,3 control the LLSV of (3) 15 ton Copeland semi's. Cool 4,5,6 control the unloaders for each respective compressor. The W7100 is having fits lately and I was wondering can anyone recommend a replacement 6 stage controller thats better than W7100. I checked with my parts suppliers and nobody has the one in stock. Thanks ROC

  2. #2
    Join Date
    Jun 2004
    Location
    Richmond Virginia
    Posts
    1,078
    The W7100 is a great controller. It has been used for many years now and still does a great job. What kind of problems are you having. Sometimes the controller will need its own isolated transformer and sometimes ground problems can occur. Is it locking up and not staging on anything? If you give these guys the symptoms and settings, they'll tell you what's wrong.

  3. #3
    Join Date
    Feb 2004
    Location
    Brooklyn, NY Occupation: HVAC Service Contractor
    Posts
    258

    W7100 Symtoms

    Yesterday the buiding manager called me an said that all six stages of cooling were on and would not go off. I raised the DA setpoint up to its max and no reaction from controller. Cooling stayed on. I removed the 24 volt power supply from TR and TR and cooling shut down. They were freezing in the space so I set the DA setpoint at 65 its original setpoint when I arrived. The reset was set at 12 and the control band (Stages) was set at 8. I do not have a test plug or resistor kit for the 7100.

    Today the customer was too hot and I was in the building anyway so I checked it and sure enough I had no cooling lights on and I lowered the DA and RA pot and nothing happened. I cycled the 24 volts and still nothing. I installed a temporary remote temp control to cycle (2) compressors until I got home to download the instructions from Honeyell and to talk to the mavins at HVAC-Talk. I'm going back in the AM and I just wanted to have my s#*t together when I get there. ROC

  4. #4
    Join Date
    Oct 2001
    Posts
    6,945
    a dedicated 24v is as Trane had them for years on their big rooftops with the VAV applications and solid mounting and grounds are important...check the resistor for the stages that is mounted on the left side for 6 stages.also check the slip connectors and resistances on your D/A sensor back to the W7100.on that staging? they run the 3 compressors thru the LLSV to start,THEN the unloaders 4,5,6 must have something to do with the coil coverage on the evap.

  5. #5
    Join Date
    Jul 2001
    Posts
    159
    about 10 years ago when i was an apprentice i remember going around to almost every job we had with 7100's with my neighbor the field supervisor. we installed lead shields made from lead pan, (the stuff plumbers use under tile showers) to keep radio interfierance down that was locking them up once in a while. it worked verywell and the jobs that still use these controls have not have a problem since

  6. #6
    Join Date
    Feb 2004
    Location
    Brooklyn, NY Occupation: HVAC Service Contractor
    Posts
    258

    Blue R1 / Maxster

    It's funny that you say that the control locks up. I used to service this unit 10 years ago and that's exactly what would happen. It would lock up and we would turn the unit off and back on and everything would be fine for months. It's like the control doesn't know wether to s#*t, piss or wind it watch. Where does the lead shield go?

    Maxster the only difference between now and years ago was that PJ Mechanical installed (4) averaging space sensors for the the tenant about a year ago.They tie into the control as well. They are not of my concern as per the buiding manager's instructions. Ha!

  7. #7
    Join Date
    Jul 2001
    Posts
    159
    we only did this on roof top units for the most part but a few mechanical rooms has some kind of electrical noise that would freek them out. we just cut up the lead to fit behind the controller, a ring around the sides and a cover that would overlap the sides slightly and have a lip on top to hold it in place my neighbor used to be a plumber so it was a piece of cake for him. as maxter said you need to make sure your grounds are good go right to the source not thru the lead. check the 1/4" male stubs where the female stake-ons clip too, sometimes they get corroded and throw off your sensor reading

    do you have any of the test kit? there is a jumper plug to ramp up the staging that will bypass the time delay between stages. don't see many of these controls anymore, it might be worth your while to just get the test kit its not too pricy

    also those averaging space sensors might be picking up noise thru the wiring if its not shielded cable

    [Edited by blue_r1 on 08-17-2004 at 09:56 PM]

  8. #8
    Join Date
    Oct 2001
    Posts
    6,945
    those space sensors should be in series/parallel as 2 wires back to the controller 6 and 7,that control band isn't staging it is reaction book says.set at 4 for 6 stages...8 would be a slower staging 2 to 3 stages,and 4 a quicker reaction.drop that RESET to 5 on the cooling ring,with 4 on the control band and some how verify those zone sensors off a print as to how they are wired coming back to the W7100 page 12 of the W7100 book shows the hook-up.i had that company one time on a new Trane SWUD self contained with the UCP-1 blue lighted LED controller,they added a W973 and i was going to void the warrenty or have them arrested for that..they constantlty over control simple jobs...would like to hear if the setting change made a difference or the sensors wiring!how about those black resistor looking surpressors...trane put on all the coil loads to keep the noise down is it near the line contactors?

    [Edited by maxster on 08-17-2004 at 10:21 PM]

  9. #9
    Join Date
    Feb 2004
    Location
    Brooklyn, NY Occupation: HVAC Service Contractor
    Posts
    258

    Follow Up

    Went back to the unit today and checked grounds, sensors and all field wiring. Everything was where it was supposed to be and correct as per the unit's diagrams and factory specs. I used the toubleshooting guide from Honeywell with the fixed resistors and I got bupkiss. The control is shot. I have a W7100 control from another job that I saved when they demolished the units. I will return again and swap them out.I called Honeywell and got a foreign women who wouldn't pass me through to a tech rep. She gave me my NY suppliers phone # and told me to talk to them. I said forget it been there done that. What's wrong with this country today. Outsoursing everything to to the Middle or Far East phone reps. It's exasberating.

  10. #10
    Join Date
    Aug 2003
    Posts
    1,311
    I'M IN CAPS CAUSE ITS IMPROTANT. HARD LESSON HERE NOT MINE BUT COUOLD HAVE BEEN. IS THE LOAD LIMITING RESISTOR IN PLACE? HAD A ROOFTOP THROW THREE COMPREESORS IN THREE YEARS. REASON WAS THE EXACT SAME SYMTOM. NO RESISTOR ACROSS TERMINALS TELLING W7100 HOW MANY STAGES ONLY FOUR ON MINE SO IT WAS EASY TO SPOT WITH SIX STAGES RUNNING (2+2=6 HELL NO) it also makes the unload time eratic and unreliable.

    by the grace of god and a strong desire to be the tech that did'nt lose a compressor on this job i found the lack of resistor.

    the jhonson modular din rail mounted modules could replace and probably beat the going price on the 7100.
    look for parts like y350 although i think thats the power module

    [Edited by hvac3901 on 08-18-2004 at 10:57 PM]

  11. #11
    Join Date
    Feb 2004
    Location
    Brooklyn, NY Occupation: HVAC Service Contractor
    Posts
    258

    hvac3901

    Unfortunately for me the load limiting resistor is in place on the control and the ohms check out for six stages of cooling. Will post my follow up when I get it running today.

  12. #12
    Join Date
    Feb 2004
    Location
    Philadelphia
    Posts
    104
    Probably too late but don't waste your time trying to get the W7100 going - just get rid of it. Look at the Johnson Controls "System 350" product line as hvac3901 recommended to replace the W7100. You can go up to ten (10) stages with it. Any refrig/ac/controls wholesale distributor in the metro NYC/NJ area worth his salt keeps these on the shelf. You're looking for A350P control module, D350 display module, Y350R power module, R353 staging modules. Stuff is inexpensive and works. You could also use a Johnson Controls UNT unitary controller but that will require you purchase Johnson "Configuration Tools" software to program it if you don't already have it.

    If you swap out the one that died and the old one you put in ****s the bed two months from now you're right back in the soup again. I wouldn't like to be in that situation - been there one too many times before. That's why I have a new, in the box, six stage cooling W7100A1053 (1999 date code) sitting on the shelf in my garage. Fought the urge to put it in and went with new stuff. Go with the new stuff - you're better off and so is your customer in the long run.

    There is a good, American, specialty controls distributor that I use in Philadelphia. They know the Honeywell stuff well. Company is NECC - 800-227-9800.

    Good Luck

  13. #13
    Radio noise from CB's and HAM radio's can do it to, drove us nuts for 3 weeks! Every Tuesday at 0915, called Honeywell and said to send the oldest bird they had out, and they did! 82 to be exact, the man stood and turned in a circle pointed to the linear beams and said there is your problem.

    So adding lead sheilding or some other form of RF asorber might work.

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