Standing Column Help Needed

Discussion in 'Standing Column Well (SCW)' started by thackery, Jan 3, 2009.

  1. The point I was trying to make is that if your pumping from static level, through the HX, the back to 500' + down, there will be some pull, seems like an awful large pump to basicly start a siphon, I think his new pump has a better performance curve than the old, and once siphoning has started, its cavitating the pump.

    Possible solution, Install a smaller pump, or a Franklin "Mono-Drive" that will retrofit VFD drive to Their standard motors, To test this theroy you could simply close a valve on the return line, to create back pressure.

    Mark
     
  2. GeoXNE

    GeoXNE Guest

    Trying to understand I got that from here-
    OK so there is no such thing as -psi. The unobtainable true vacuum would be 0ATM. At 1ATM anything under 14.7psi would be in vacuum??? Am I correct?

    If this is the case will a pressure gauge be accurate below 14.7psi (or not because it doesn't take into account ATM pressure)? And that's why we use a manometer (in inches of WC or HG) for things that suck?
     
  3. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Have to be a bit careful with psi, mostly because there is nearly always a letter missing: -g, -a, -d.

    In popular usage, we nearly always mean psig, pounds per square inch guage. If I say a tire has 30 psi, that's really psig. Tire guages and most others are calibrated to indicate 0.0 when open to atmosphere.

    PSIA refers to pounds per square inch absolute and represents the pressure above pure vacuum. The tire in the above example would have 44.7 PSIA if the 30 PSIG were measured at sea level.

    Less common is PSID - pounds per square inch differential. We might see that in geo while calculating water flow through a heat exchanger. A couple of pressure measurements (psig or psia) might reveal 3.0 PSID across an operating heat exchanger, and a table lookup for a particular model might show that corresponding to 10 GPM flow.

    Technically the tire has 30 PSID if the guage were zeroed to the atmosphere just before taking the reading, but I wouldn't suggest requesting that your tires be inflated to xy PSID at your next service...
     
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Engineer

    I love the way you explain things.

    <<<<goes off to buy new tires for the motorhome.
     
  5. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    All part of the package...
     
  6. Looby

    Looby Member Forum Leader

    Correct! In absolute terms, there is only pressure; it may be high, low, or zero,
    but it can't be negative. Absolute pressure lower than ambient atmospheric is
    commonly called "vacuum," but that's an artificial concept. There's no such thing
    as vacuum -- only pressure.

    Depends on the type of pressure gauge. For example, some manometers have
    the "reference end" open to ambient air -- and thus indicate gauge pressure.
    Other manometers have the reference end at (nearly) 0 psi absolute -- and thus
    indicate absolute pressure.

    http://en.wikipedia.org/wiki/Manometer


    Looby
     
  7. GeoXNE

    GeoXNE Guest

    engineer & Looby

    Thanks for the physics lesson. I appreciate it.

    My 7th grade shop teacher who had the uncanny ability to motivate even the laziest of students would say at least once a day-
    "It is easy if you know it, haarrd if you don,t"

    So, back to OP and practical application. What is actually happening in an injection loop drop pipe that is over 34' to water at 1 ATM?

    If we had clear pipe (barring pipe collapse and leaks), would we see a 34' column of water above static level and then void to the highest point in the system (when the system is off)?
     
  8. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Yes, but a bit less than 34'. Some of the water boils off, depending on temperature, preventing realization of an absolute vacuum.

    Practical limit to the height of a column of water open to atmosphere at its bottom for pumping purposes is on the order of 25'.

    If you connect a clear beaker or bottle of water to a vacuum pump you can watch water boil at room temperature. It makes lousy coffee and won't cook an egg, though.
     
  9. ncgeo

    ncgeo Member

    I haven't joined the forum in quite some time, but when I do find the time the discussions are so relevant and helpful. And they also prompt some questions of my own ...

    A general question on standing column operation ... why is it often suggested the injection occur near the bottom of the well? In heating mode it would seem more favorable to inject water near the top so the sinking cold water mixes with the column before being pumped again. And with injection near the top, in cooling mode the pumped water would be some of the coldest in the column. I base this on my observation in different wells the pump was nearer the bottom of the water column. Although I suppose pump placement in the column could vary with the installation.

    Is there some disadvantage to injecting near the top of column? Should the rule be to inject at the point in the column farthest from the pump, to maximize mixing(?)
     
  10. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Ronaldg,

    Typically it is pump-bottom discharge-top.

    Ooops should add - unless you are returning between the casing and an interior sleeve.
     
  11. thewellguy

    thewellguy New Member

    maybe?

    check for leaking o-rings on pitless adapter
     
  12. bobpietrangelo

    bobpietrangelo New Member

    I would not disable 3rd stage heat. If your system was designed properly for your locality, it most definitely will require auxilliary heat. If it was not your cooling in the summer will be drastically oversized and not able to remove enough humidity during the summer. If you disable your aux heat it will overburden your loop and cause more issues.

    If you do disable 3rd stage heat at the circuit board, if there is a call for emergency heat it will still energise, it will just not operate as your 3rd stage of heat.

    The way the 2 stage Envision is designed to operate you require a 3 heat 2 cool thermostat. Waterfurnace makes several styles that communicate with the equipment much better than your exisitng thermostat. If your contractor installed the W01 stat due to a lack of wires WaterFurnace has a TP32U04 which only requires 4 wires to communicate. It also has a function called Comfort Talk. It relays text based diagnostic information directly to the thermostat so that if your system malfunctiones it would give a precise reason why and the phone number to dial for service. You c an also adjust the deadbands between thermostat stages to make it longer before the electric heat is energised.

    You should always uitlize a 3 heat 2 cool stat when installing WaterFurnace residential equipment.
     

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