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  1. #1
    Join Date
    Jul 2004
    Location
    Pahrump, Nv.
    Posts
    16
    Just got stuck ressuecting a mammoth unit the other day.The unit itself is in decent shape, retains all its original controls, and hasent (suprisingly) been raped and a subject of modification. My problem is this. It is a package unit, water cooled. Turn it on, close all switches, take it outta morning warmup, and drop the setpoint on the 7100 to 40*. All six stages light up. And heres where I get lost. There is no technical lit on the unit, just the wiring diagram. From that I can tell stages 1&2 on the 7100 energize the liquid soledoids, and I know that of the other 4, 2 of them are for the compressors. The unit trips on high head, this would be due to the condenser water valves not opening.

    Here is my big question, are two of these stages for the water valves? If so, I can understand that, but what about the part of the print that shows the wiring on these valves going to the Economizer terminals on the W7100. Thats DC voltage, right? The valves are the Honeywell Modutrol. It just says 24V for power. If Im not mistaking, this unit also has a free cooling coil tied into the same lines, kinda like a bypass. I got tomorrow off, so, if anyone has an idea, or experience with these, drop me a line. It would really be appreciated.

  2. #2
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,498
    on the mammoth i have worked on the water pump for the condenser spray pump is not tied to the 7100. i dont remember what brought it on. but it needs to be on. the ones i had had hitachi screws and the 7100 loaded it up. you will probally need to find a place to study the diagram. mine had about 11 pages so i made copies and high lited different circuits to keep from loosing where i am at when i traced it out.

  3. #3
    Join Date
    Oct 2001
    Posts
    6,966
    think of the water side economizer the same way as if is outside air economizing,the water must be able to economize thru its temp so their must be a sensor to Ok the call for econo cooling and let the actuator pass the water.their is no cooling stage for econmizing it is basically a ramp within that is just below the COOL 1 and will keep it off as long as the water can satisfy the setpoint on the W7100.how many compressors are there and are the semi or scroll and do the have unloader if semi.they might be using the C1/C2 for LLS starts come back with the compressor setups and totals.

  4. #4
    Join Date
    Jun 2004
    Posts
    51
    Sounds like you have a V-Cube unit with a Wise coil. Regardless of the economizer valve position, the water should still pass thru the condenser barrel provided the valve is really open. Some units are built so the valves shut off when the unit is off to direct condenser water flow to other units and/or slow down pumps via demand requirements.

  5. #5
    Join Date
    Jul 2004
    Location
    Pahrump, Nv.
    Posts
    16
    Well, the area this unit is serving just underwent some major changes. It use to be office spaces, now its for UPS equipment. This has increased the load dramaticly. So economizer is not necessary.

    I had assumed as well that the moment power was on, that the valves were open. There are other things I can check, its just I was curious what the w7100 would have to do with the valves. Its my assumption, that as soon as the disconnect is energized, the water valve transformers will provide 24 volts instantly. I think I may open up the top of the valve, see if its gettin 24v.

    For those who asked, there are 2 stages mechanical cooling, semi compressors. The fan is operated through a VFD, and has no trouble pulling an inch of static at 60%. Appreciate the help guys.

  6. #6
    Join Date
    Oct 2001
    Posts
    6,966
    do you have the letters and numbers after the W7100 on the bottom of the controller...if you see R/B/W on the face of the controller it modulates the valves...if it is just heat NO/NC/C as the cool is it is open and closed on the actuator.the W7100 would be looking for a changeover into itself for cooling or heating swings and the dial would have to be reset for that conditioning.if you get that letter info i will put up that controller wiring and all its add on external controls.

  7. #7
    Join Date
    Sep 2002
    Posts
    1,389

    tommytoons

    Call (800) 328-3321 and ask for Otto Rice in the Service Dept.
    Have the model and serial available for him. He will know exactly where the unit is even located (job name and address). He will also get with engineering and fax you any and all info you require.
    Hope this helps,
    tom

  8. #8
    Join Date
    Jul 2004
    Location
    Pahrump, Nv.
    Posts
    16
    Actually we found the problem. The valves were operating fine. After tracing the tower water pipes, I found a butterfly valve closed. After that it was running fine. A little low on charge, and a head pressure switch in stage 2 was bad, but it was all running good when all was said and done. Appreciate the help guys.

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