Retrofit Standing Column Well, what systems did you replace?

Discussion in 'Standing Column Well (SCW)' started by stevecaz, Jun 11, 2009.

  1. stevecaz

    stevecaz Member

    Re: Retrofit Standing Column-what systems did you replace?

    I'm a geologist and have the water level meter (well its from my company). But you can rent them at an environmental and/or survey equipment rental place. Try searching the internet for one in your area. I think the place I rent certain equipment from charges $20/day for one.

    Part one of the test is complete and I'm analyzing the numbers. I want to do a second test at a different flow rate for correlation and comparison.

    Stay tuned.
     
  2. stevecaz

    stevecaz Member

    Re: Retrofit Standing Column-what systems did you replace?

    Results of my well test for determination of discharge pipe:

    My well (6” diameter) is 400 feet with a reported 20 gpm yield upon install in 1987. The ¾ HP pump is set at 300 feet. Casing is set to 30 feet with bedrock at 25 feet. The reported main water bearing fracture is from 380 to 383. My static GW level is around 13 feet, but this is within the steel casing so as expected the recovery from 30 feet to 13 feet is very slow. A 6-inch well has 1.468 gallons per foot.

    I conducted two tests on my well at two flow rates – 3 and 5 gpm. See above post for why I used these rates. I used a marked 5 gallon bucket and a stop watch to measure flow rate. Anything more accurate than this really isn’t necessary.

    In general, a well will increase the recovery rate the further the water drops – to a certain maximum point. It took about 10 minutes to calibrate my flow using a garden hose and bucket, and even then during the test I kept retiming the flow rate to check. Naturally I found some minor fluctuations but overall fairly consistent. I could actually sense by my level readings when the flow had changed slightly.

    The well in both cases rapidly dropped down to 30 feet where the casing ends. During the test, I could tell when the pump turned on/off and was running from pressure tank as the water level would rise when the pump was off. At 3 gpm, the water level dropped to ~35 feet and did not drop below this over the 45 minute test (it fluctuated between 31-34 as the pump came on and off and went to 35’ when the flow rate went slightly over 3 gpm.
    At 5 gpm over the 1 hour test, the lowest level measured was 50.9 feet. Also during the test when the pump cycled off and water was rising, I measured the time to gain 1 foot (1.468 gallons). Rough estimates based on this method were 2.8 gpm at 35 feet; 3.1 gpm at 40 feet; and 3.4 gpm at 50 feet. Given I didn’t drop below 35 feet on the 3 gpm test, that validates these estimates.

    At the 5 gpm flow rate, I found a continued net loss of water in the well of 0.53 gallons per minute during the test based on starting and ending water levels, not counting water in the casing. This equals 31.8 gallons/hr loss, equivalent to 21.6 feet of water column in the well. There may be a depth in the well when I reach 5 gpm recharge but it wasn't necessary to determine this.

    The result: For me setting the discharge at 50 feet (top of casing) would be a safe level, which is actually about 42 feet down from the pitless adapter. I probably could set it a little higher but that only adds a couple feet of well column per ton. At 50 feet, my water level would only drop below this when running both units on full, at a time requiring a continuous hour long bleed to bring up well temperature, plus showering plus a sink on for a straight hour. This should never occur.

    By the way, could someone who knows costs of Climatemaster Tranquility series message me. I just got costs for Carrier branded units and want to see what the Carrier sticker might add to the price.
     
  3. Guest

    Guest Guest

    Re: Retrofit Standing Column-what systems did you replace?

    Sounds good. A temperature based bleed is recommended - ie, no sense in using any bleed when the well water is at a reasonable temperature.
     
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    jonr?

    How do you know that?
     
  5. Guest

    Guest Guest

    Re: Retrofit Standing Column-what systems did you replace?

    Because I read the recommendations. Some Goggle time and a lot of reading will confirm this.

    Of course it is also very logical - why would you use bleed water when the temperature is fine?
     
  6. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    jonr

    Please link me to the information. I am willing to learn.

    In the land of blind the one eye is king.
     
  7. Looby

    Looby Member Forum Leader

    Re: Retrofit Standing Column-what systems did you replace?

    Why would you install a temperature-controlled valve or pump in
    a system that required nearly continuous bleed -- or none at all?

    ...simple is better than better,

    Looby


    Mark C: Well said!

    "In regione caecorum rex est luscus."
    -- Desiderius Erasmus
     
  8. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Re: Retrofit Standing Column-what systems did you replace?

    Surf the writings of Carl Orio for more SCW info.

    From what I read, temperature-based bleed is fairly standard, and should only be required when domestic use is not ocurring. Domestic use serves in lieu of bleed.

    Ideally, bleed is only needed during climate extremes, but much will depend on the specifics of this existing well.

    Introducing mineral oil into a potable water well sounds like a horrible idea, and I assume it would be unlawful.

    An ultraconservative approach would be to use an intermediate exchange loop or double walled and vented heat exchangers to insure refrigerant and compressor oil can't get into the water. I think code requires the latter in some places.
     
  9. stevecaz

    stevecaz Member

    Re: Retrofit Standing Column-what systems did you replace?

    I'm confused on what the confusion is from these last posts.

    The heat pumps have a recommended minimum temperature. Since in the heat cycle the discharge water is around freezing, the entire well temp will begin to lower. (again this is all about standing column systems). Therefore an automatic temp controlled bleed valve is ideal to open when this temp is reached, and shut down some degrees above the minimum. Its difficult to really know before you have an operating system if bleed will ever be needed and how often. Each well will behave slightly differently, but in general, the recommended 60-100 feet of well per ton is based on experience that this will provide enough latent heat to not require bleed, except maybe on extreme cold days when the system is running non-stop.

    I suppose in theory if you have a 50 foot well with high yield, you could do a 5-ton standing column system - but you would be bleeding profusely and constantly to maintain the water temperature.
     
  10. redneck_savant

    redneck_savant New Member

    Consider dropping a closed loop down that well. PE pipe is relatively cheap, and you won't wear out your potable water pump. I bought a 2 pump QT flow center and had to throttle it back quite a bit - it was a bit too efficient.

    My geo system uses a 5 to Geocool, I used 3/4 PE pipe down a bored vertical well depth 540 with water contact for the first 380 feet of the well - dropping the pipe down that well required no special tools other than leather gloves. Why? I filled the loop AFTER install. My well did have a 6" PVC pipe tile at the top, I had to work to lift the last 200 feet of my vertical loop off that so it didn't shave off some of the PE pipe - other than that it was an easy 1 man job. (The bouyancy of the pipe in the water made it easier to lower down there than otherwise would have been the case.) If filled with water, that pipe's going to break your back, your rig to lower it, and your pocketbook. Fill it later!

    Oh, one final tip. I share this well with my drinking well as an additional reservoir. Didn't want to use any toxic form of anti-freeze accordingly. What did I use? VODKA! Just the cheap kind. If it leaks into the well, just something else to smile about as I sit in my cozy warm geothermal house!

    Barring that, you could use an indoor reservoir with that well - an insulated potable water tank filled with pe pipe can make a more than adequate heat reservoir. (I've a patent pending on both the ideas - but patents don't prevent private individuals from using them for personal use.) If any of the big installers here start using it though.... $$$$ =)
     

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