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Thread: Engineers....

  1. #1
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    Engineers....

    When a civil engineer comes up with the plans for new building, you end up with a package unit placed above the drop ceiling, serving a server room.

    Oversized at that.



    Thank goodness it was a trane compressor with rotolocks.


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  3. #2
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    I had something like that at the last place I worked. It was essentially a package unit, but built in two halves, to be able to squeeze into tight places. It was at a convenience store. Mounted on a steel framework above a ~10 door walk in cooler. I hated getting a call for that unit.

    The electrical and belt drive was accessible on one side of the unit while standing on an extension ladder. But to get to everything else, you had to move the ladder to the other end of the walk in, climb up, then walk across so you could climb up on the steel framework.

    This convenience store, as are most, don't provide a lot of room for moving an extension ladder around. Pretty common for someone to try and move the ladder while I was working on top of it, just to get their sugar drink.

    Oh yeah, first you had to drag another fold out ladder in there to remove the ceiling tiles. Glad I'll never see that unit again.
    A skilled Tech would solder a relay on that board and call it good to go.

  4. #3
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    Still see this crap a lot. Got a call from a school that an AHU was down. We get there and it's like 15 ft. in the air above a drop ceiling. The controls and access panels are against the wall. Also half of the unit and duct work is above a flight of stairs. to even look into the control panel you have to twist your body completely around or climb the ladder backwards. I ended up finding the freeze stat is tripped and it's Sept.

    The freeze stat is above the stairs. I can't reach it but I see a 3' x3' hole in the wall. I ask the maintenance guy about the hole and he says that's how they change the filters. I pop the blower compartment open and 90% of the belt is gone. There's a piece with the size on it. Of course they don't have the right belt. They have an inch shorter one so it's backwards on the ladder to change it. Then get a shorter ladder out and go into the nurses office, move her desk and go up into that ceiling through the hole and hit the reset

    Worst part about it. The unit was down for a month. They finally called on a Friday afternoon after 3:30 and insisted we come right out!
    There's TREACHERY AFOOT!!!

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  6. #4
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    Where I used to work they have a 60" belt-drive return fan 16' in the air. Of course, it's above a drop ceiling so you'll have to take the ceiling apart to get a lift to it. Oh, and the fan made the offices (directly below) almost unusable from noise.
    Same building, there was a "floor 2.5" mechanical space with an air handler. During the reno they took out the AHU and the floor slab... then they put a new AHU in. Now you need to stand on a ladder on a lift to get to it because of piping. But hey, at least the ceiling is higher, right?

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  7. #5
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    No, trust me, as engineers we're ripping our hair out at those. The idea of heat-generating objects in the plenum beyond the lighting (which we account for) throws all our calculations off like heck. A three ton package unit in the ceiling with plenum return generates more than three tons of load that doesn't show up anywhere in our floor plan - essentially phantom load we often don't account for in our design (unless we know about it, and a lot of times these sketchy jobs were done non-permit). Which leads to "why the *bleep* can't the unit maintain supply air temperature" calls where we get yelled at about how our design was terrible and bad and now everyone is warm. And of course it can't be the fault of the package unit, that thing is "in the ceiling" and everyone is warm in the office, not the ceiling.

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  9. #6
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    Thread Starter
    Quote Originally Posted by KRHVAC View Post
    No, trust me, as engineers we're ripping our hair out at those. The idea of heat-generating objects in the plenum beyond the lighting (which we account for) throws all our calculations off like heck. A three ton package unit in the ceiling with plenum return generates more than three tons of load that doesn't show up anywhere in our floor plan - essentially phantom load we often don't account for in our design (unless we know about it, and a lot of times these sketchy jobs were done non-permit). Which leads to "why the *bleep* can't the unit maintain supply air temperature" calls where we get yelled at about how our design was terrible and bad and now everyone is warm. And of course it can't be the fault of the package unit, that thing is "in the ceiling" and everyone is warm in the office, not the ceiling.
    I️ can’t imagine it creates to much load. The condenser fan is ducted outside as well as the Supply for the economizer and condenser intake.


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  10. #7
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    Wait, they ducted the condenser fan? They do know that's good for about 0.1" of static on a good day, right? Ducted condenser fans almost never work. The only time I've used one successfully was in a mechanical room where it was effectively outdoors (just in a huge louver).

    Usually someone realizes this if they did duct it and rips the condenser fan duct out, which solves one problem.

  11. #8
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    I've seen a couple of handfuls of ducted condenser fans through the decades, and if done properly, they seem to work okay. The real problem has to with service and things like cleaning the coil.


    Quote Originally Posted by KRHVAC View Post
    Wait, they ducted the condenser fan? They do know that's good for about 0.1" of static on a good day, right? Ducted condenser fans almost never work. The only time I've used one successfully was in a mechanical room where it was effectively outdoors (just in a huge louver).

    Usually someone realizes this if they did duct it and rips the condenser fan duct out, which solves one problem.
    A skilled Tech would solder a relay on that board and call it good to go.

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  13. #9
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    Quote Originally Posted by KRHVAC View Post
    Wait, they ducted the condenser fan? They do know that's good for about 0.1" of static on a good day, right? Ducted condenser fans almost never work. The only time I've used one successfully was in a mechanical room where it was effectively outdoors (just in a huge louver).

    Usually someone realizes this if they did duct it and rips the condenser fan duct out, which solves one problem.
    The unit is designed for this application. Tithe unit is the brand. First I️ heard of them was this one.

    My grip is a traditional package unit would have been fine on the ground or roof. But, of coarse they didn’t want to see it, so they shove this unit above the ceiling.


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  15. #10
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    First I heard of them too. Tithe? That's pretty cool. I'm going to keep that in mind if I ever need a 24/7 cooling unit on a low floor in a high rise building.

    Does seem like a lot of work for no real payback though if you can get to the roof. Plus I'm sure that's much more expensive than a Mitsubishi or Fujitsu split.

  16. #11
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    funny you say that. a mitsu is going in the room next week. their current back up generator cant handle the extra load of that package unit, so whenever the building loses power, they lose cooling to the server room. so were hooking the mitsu up to the emergency power supply.

  17. #12
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    Included in a hospital balance job I had an out building to balance. When I opened the door the unit was off so I turned the stat down to 65 F and started bringing my tools inside. This was a hot day but before I got my tools in the door the unit satisfied and shut off. The room was 8'x15' so I wasn't too surprised until I looked at the plans. Believe it or not the AHU was 12 tons. There was only about a foot clear space on each side and a little more on each end of the unit and it was installed prior to the roof going on. The engineer made up for it by under sizing the heating water system in the main building.
    At least Trump doesn't eat dogs!!

    Never answer an anonymous lover. Yogi

  18. #13
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    Most times I find the troffer fixtures blocking all access points to equipment.
    “You don't get paid for the hour. You get paid for the value you bring to the hour.” Jim Rohn

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