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  1. Bringing it back to my example case, these motors...

    Bringing it back to my example case, these motors do have shaft grounding rings, and are not failing due to electric arcing. That results in a very tell-tale fluting of the bearing race. We've even...
  2. Sorry mate, were talking about air handlers, not...

    Sorry mate, were talking about air handlers, not chillers/condensers/whatever else you are thinking about.
  3. I also have the benefit of a nearly identical...

    I also have the benefit of a nearly identical hospital built a few towns over with the same general floorplan/design, so air handlers from the same manufacturer but done with belt drive fans serving...
  4. Sorry, but most of these points are simply false...

    Sorry, but most of these points are simply false or inconsequential. I'm not even sure what you are talking about chillers for. Vfd cost is the same for a given total horsepower.
  5. You need to understand where my perspective comes...

    You need to understand where my perspective comes from on this, and what I am comparing. I am a maintenance guy at a large hospital campus that has seen steady construction since 1955. As such, I...
  6. Engineers need to stop with the fan array designs...

    I am so sick of every single design coming back with arrays of direct drive fans. I have yet to service one that didn't have an incredibly high bearing failure rate on the motors - while the...
  7. It was not necessarily a specific desire for VRF...

    It was not necessarily a specific desire for VRF as opposed to a non-variable multi-zone. It was more that when I initially started looking at options, the cheaper brands didn't really have...
  8. VRF for your own home, what would you install?

    So, I'm thinking ahead to an HVAC upgrade for my personal home once I finish up the solar project. I've got a single 3 ton central ducted split in the home that overall cools well enough (which is...
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    In your experience, how well does the Workbench...

    In your experience, how well does the Workbench VisualLogic work? I actually really like the Visio based approach, so it's more curiosity than anything.
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    Termination is likely fine, as evidenced by the...

    Termination is likely fine, as evidenced by the rather squared-off math channel. If termination was incorrect (or missing), those signals would be either rounded high, or rounded low. It's far more...
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    Agreed, that more airflow across the coil (from...

    Agreed, that more airflow across the coil (from smoother duct flow - turning vanes) is likely going to decrease the effectiveness of dehumidification. Leaving air temp will be higher, meaning...
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    no, cut in is the point of valve position where...

    no, cut in is the point of valve position where there is measurable heat input (in this case, too much), and cut-out is the point of valve position where there is no measurable heat input.

    And...
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    and be careful when looking for COP numbers for...

    and be careful when looking for COP numbers for chillers, as quite often they will reflect the efficiency of a chiller in kW/ton - which is NOT exactly the COP of the chiller - COP doesn't have any...
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    Example, looking at a chiller that's sitting in...

    Example, looking at a chiller that's sitting in front of me right now:

    (54.5F-42.8F)*2700gpm / 24 = 1316 RT * 3.51685kW/RT = 4628.178kW of heat being removed from the chilled water.

    The...
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    why would you need that information? Calculating...

    why would you need that information? Calculating the tons of cooling from the aforementioned formula (and converting it to kW) and using kW is all you should need to determine the COP of the chiller.
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    Got to rework the formula, bake in your metric...

    Got to rework the formula, bake in your metric conversion (note, since you're only caring about delta-t, you don't need to care about the offset for F to C conversion, just the factor).
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    Oh yeah, I certainly understand the runtime...

    Oh yeah, I certainly understand the runtime aspect of the actuator. I actually think that this is less drive time than the previous situation, where it was almost constantly moving either in or out...
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    You've already lost before even talking to him. ...

    You've already lost before even talking to him. Odds are, he's half your age, and has never even seen the equipment he's designing.
  19. I'm a controls guy with a lot of mechanical...

    I'm a controls guy with a lot of mechanical experience, and I will say that 'balance' isn't as important as satisfying the load on the building. It really doesn't matter what GPM a given coil is...
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    Here's a visual of how it's now operating...

    Here's a visual of how it's now operating (cut-in=40%, cut-out=30%):
    815343
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    Oh, I'd much rather have properly operating...

    Oh, I'd much rather have properly operating valves and properly sized reheat coils - but this sequence is one that CAN work with any reheat valve, and if that particular valve doesn't require the...
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    Pulse-width modulating an analog valve.

    So, I had to do an 'emergency brain transplant' on an air handler that served 4 zones in the radiology department. The previous controller had died, and we had no information on previous sequence...
  23. If you are pulling air out of the box (the...

    If you are pulling air out of the box (the building), then air will also be flowing back into the box. If you don't give a specific path for that air to go in through, than it will find it's own way...
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    In the systems I've worked with, the chilled...

    In the systems I've worked with, the chilled water provided to the MRI equipment is essentially condensing water for the cryo chiller that keeps the superconductor's helium shield cool. Typically,...
  25. Poll: There are plenty of units out there.. Geothermal...

    There are plenty of units out there.. Geothermal is just one of the ways of getting much better thermal performance - another is evaporative condensing units - it all depends on the climate. The...
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    Not entirely sure what you are asking - but I...

    Not entirely sure what you are asking - but I think you are talking about in VisualLogic, the different tabs/pages in the document. Those tabs are essentially just pages for your own use to organize...
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    I believe this is set as the ToS (Type of...

    I believe this is set as the ToS (Type of Service) in the IP Packet header - which can be used by some routers to determine routing priority. I honestly cannot ever foresee a reason to set this to...
  28. Replies
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    Webtalk can export that info... or, depending on...

    Webtalk can export that info... or, depending on how computer saavy you are, you can open the files directly from excel, but it takes some learning to figure out how they are stored and archived.
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    True, but it did get me to read through that...

    True, but it did get me to read through that great thread....
  30. Replies
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    One could make logic that does count...

    One could make logic that does count hour/minute/day/month/year AV's, triggered by the currtime object, if desired, but it might be just as easy to have a very cheap/simple bacnet clock...
  31. Replies
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    While true, I can't see a real use case for...

    While true, I can't see a real use case for needing it. The question posed here was more an issue of an absolutely terrible engineer, than it is a limited platform. Seriously - there's no excuse to...
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    As I was saying, the hardware supports analog...

    As I was saying, the hardware supports analog schedules just fine, and I use them often for resetting room temps and such - it's more an issue of the terrible Envision software making assumptions...
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    While you can read device object properties in...

    While you can read device object properties in VisualLogic (off-hand, that would be written in visual basic as T8-0-56, or something similar), it can't handle non-numeric data, so it will read in as...
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    I think the issue, PHM, is that the humidistat...

    I think the issue, PHM, is that the humidistat itself is in the room, so it gets to its setpoint very quickly, and shuts down the solenoid valve. This is why there isn't a significant humidity...
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    Unless outdoor dew point is relatively constant,...

    Unless outdoor dew point is relatively constant, you cannot determine that 'low relative humidity' is the result of an improper air change or not. There is a given amount of moisture in a room, and...
  36. Any piece of equipment that can be damaged by a...

    Any piece of equipment that can be damaged by a very short power dip or outage should have electronics in place to delay restart. The electronics to accomplish this are ridiculously cheap, so...
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    Having an oversized furnace is not going to be...

    Having an oversized furnace is not going to be the end of the world. A 2-stage would be nicer, as it would minimize the instabilities of the unit cycling on and off, but I'm not sure the amount...
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    Part of the overall issues, and something...

    Part of the overall issues, and something particular to gyms and dance studios, for instance, is that indoor moisture build-up is not related to outdoor moisture levels - unlike...
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    I believe that technically, the louvered door and...

    I believe that technically, the louvered door and mech closet ARE the return plenum. This is hardly an uncommon install practice. My only real issue with this install (other than the OAT sensor...
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    If you are unable to get a refund on the 400, the...

    If you are unable to get a refund on the 400, the price of the 700 is likely going to be more than finding a real installer to put a short plenum on the furnace inlet, or even cut in a new port on...
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    Did you ever find a good solution for this? My...

    Did you ever find a good solution for this? My hunch is that a 'custom' item would be required here for the best use - something like making up and sealing a cable of 1-wire temp sensors (Maxim...
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    I think it you really wanted to define it, it's...

    I think it you really wanted to define it, it's be any system that cools a working fluid, and that working fluid then cools the load. This would be in contrast to a DX (Direct eXpansion), where the...
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    DewPoint should stay fairly steady day to night...

    DewPoint should stay fairly steady day to night (as you said, unless a weather shift moves through that brings in or takes out moisture). Wet Bulb =/= Dew Point though, and in some regions (dryer...
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    The IDCP is not in Saudi Arabia, and has nothing...

    The IDCP is not in Saudi Arabia, and has nothing to do with any Mosque or Mecca. The IDCP that is described is the plant in Qatar, on 'The Pearl' - a man made island, where it cools nearly every...
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    Also, no storage, but this: 130,000 tons...

    Also, no storage, but this:

    130,000 tons
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    Something else you'll notice in the TECO images,...

    Something else you'll notice in the TECO images, as well as most district cooling plants, is the massive Thermal Energy Storage tank. That is a huge part of the overall system efficiency, in that...
  47. I think you (whatever GOOD designer you find)...

    I think you (whatever GOOD designer you find) need to first look at the structure, and completely ignore what is currently there. Come up with the ideal design that will say how much heating and...
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    Looks like it's in the process of fixing itself...

    Looks like it's in the process of fixing itself anyway, right?
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    Don't be afraid to sit on your ass or hip instead...

    Don't be afraid to sit on your ass or hip instead of kneeling. Humans weren't made for kneeling long, and we've got nice padded rumps for a reason.
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    that certainly does look crowded. That tight of...

    that certainly does look crowded. That tight of quarters I'd worry about the 100% OSA units pulling in a lot of condenser heat.
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