Question on diagonal loop installation

Discussion in 'Geothermal Loops' started by bawalker, Jan 15, 2012.

  1. bawalker

    bawalker New Member

    [FONT=&quot]I recently had a 4-ton geothermal system installed, which the ground loop was supposed to be 8 -75 foot deep vertical wells due to the small possibility of old mines in the area. The day the well driller began, he changed the arrangement to 4 -150 diagonal wells. All were connected into a parallel manifold before going into the return and supply lines.[/FONT]
    [FONT=&quot]
    [/FONT][FONT=&quot]The concern I have is that two of the wells were bored at 35 degrees from the vertical and two were bored at 65 degrees from the vertical. From my calculation, there is about a 60 foot head difference between the bottom of the 65 degree and the 35 degree wells.
    [/FONT]
    [FONT=&quot]The unit is unable to keep the house warm when the temperature drops into the mid to low 20s, basically is continuously running with no off time and a spiral down in air temperature from the registers. I typically have kept the thermostat at about 67 degrees but when this occurs depending upon the outside temperature, it can be difficult to maintain even 60 degrees. The unit installer agrees that the unit is not performing properly and was told that the thermostat was the problem. I did not think that was the problem and the different thermostat has had no effect at all.[/FONT]
    [FONT=&quot]
    [/FONT][FONT=&quot]This seems to be the symptoms of short-looping. I wonder if the lower wells (bored at 35 degrees) are performing properly, or at all. I think an exaggerated example would be combining vertical and horizontal loops into the same manifold without adjusting for the head difference.[/FONT]
    [FONT=&quot]
    [/FONT][FONT=&quot]Some information on my house:[/FONT]
    [FONT=&quot]1-1/2 story house with a basement, 1,800 SF finished and heated area with 450 SF of this in the basement, about 500 SF has a peaked cathedral ceiling to about 25 FT, insulation is good to very good per construction drawings (R38 to R40) – I did not build the house.[/FONT]
    [FONT=&quot]
    [/FONT][FONT=&quot]Does anyone have any experience with this and is it an acceptable installation? If this is a problem what might be the most effective fix (flow equalization or connecting two different angled wells in series and then into the manifold)?[/FONT]
    [FONT=&quot]
    [/FONT][FONT=&quot]Thanks for any assistance.[/FONT]
     
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Thoughts

    There is no "head difference" in a closed loop system (for equivalent length/diameter runs).

    The only way to determine if you're short-looped is to monitor the entering water temperature

    The difference between vertical and horizontal for performance really starts at about the 20' depth mark. So a back of the envelope calculation to determine how much "more" of your pipe is now above that 20' mark vs. a full vertical system would help determine how much "out" your system is vs. a straight vertical setup. Roughly.

    Depending on a lot, a vertical system usually has about 1/2 the pipe of a horizontal equivalent. So as your vertical system becomes more "horizontal", one would expect an increase in overall piping. This may/may not be an issue with your system.

    My guess is your loop is good. Otherwise your unit would shut-off. The problem then becomes that your system is too small for the house. But it could be as simple as 2nd stage not kicking in.

    .
     
    Last edited: Jan 15, 2012
  3. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    The angle of your loop is not a concern.
    If your loop is 90 degrees or 45 degrees it has the same "head" since your pushing water down one pipe as water is being pulled out of the other pipe.
     
  4. bawalker

    bawalker New Member

    Thanks for the comments. It does appear that it was the 2nd stage not coming on. The contractor has used a Honeywell thermostat, Vision Pro and he said after trying to get it to work properly for several weeks that the newer versions do not have the same capability to automatically go into 2nd stage. I listened to him discuss this issue with their technical staff for an hour while he tried to get it to work.

    He kind of solved the problem by putting in a timer and set it at 8 minutes so after the unit has run 8 minutes in 1st stage the 2nd stage goes on.

    This does not seem like the most efficient or intuitive way to deal with this. There must be a thermostat out there that does it automatically.If there are any suggestions I would appreciate it. And if they are Z-wave capable even better.

    Just to provide additional information, my geothermal unit is a Bosch 6000 TA, 4 ton. The contractor said it should handle heating to at least 10 degrees without needing the auxiliary heat.

    Thanks again.
     
  5. geome

    geome Member Forum Leader

    It's not.
    Most do. Your thermostat should as well.
    Please list the full thermostat model number. I'll try to help you confirm settings as I have the opportunity.

    Z-Wave thermostats exist, but I am not familiar with them. The Honeywell you have may actually be better if it is the proper one for your system. Of course, a different thermostat will also cost you more money.
     
  6. bawalker

    bawalker New Member

    The thermostat is a Honeywell Vision Pro IAQ, Model YTH9421C1010.
     
  7. geome

    geome Member Forum Leader

    Is your aux heat electric?

    Can you tell us the settings for each of these setup functions without changing them? You may need to download a copy of the YTH9421C1010 Installation Guide for instructions if you don't have the guide that came with the thermostat.

    http://www.ntsupply.com/files/products/69-1816EFS.pdf

    172
    173
    174
    176
    200
    220
    230
    240
    250
    260
    347

    Homeowner with WF Envision NDV038 (packaged) & NDZ026 (split), one 3000' 4 pipe closed horizontal ground loop, Prestige thermostats, desuperheaters, 85 gal. Marathon.
     
    Last edited: Jan 22, 2012
  8. bawalker

    bawalker New Member

    Aux Heat is electric

    Thermostat Settings

    172 2
    173 1
    174 2
    176 1 Should this be 2?
    200 0
    220 3
    230 3
    240 9
    250 Not showing up; Is this because 176 is set at 1?
    260 Not showing up; Is this because 176 is set at 1?
    347 Not showing up; Is this because 176 is set at 1?
     
  9. geome

    geome Member Forum Leader

    "176 1 Should this be 2?" This could be why 2nd stage isn't engaging. The proper setting could possibly be 1, 2, or 3 (2 compressor stages and 1 aux heat stage.) (See below comments regarding Honeywell documentation.)

    250 Not showing up; Is this because 176 is set at 1? Probably
    260 Not showing up; Is this because 176 is set at 1? Probably
    347 Not showing up; Is this because 176 is set at 1? It's OK to not have this option - just checking.

    So, "He kind of solved the problem by putting in a timer and set it at 8 minutes so after the unit has run 8 minutes in 1st stage the 2nd stage goes on." I assume the installer didn't do this through the thermostat settings?

    I would ask the installer if he would disable the timer, and try setting the thermostat to (leaving everything else the same):
    176 3
    240 3
    250 3
    260 9

    Then, the installer can go through the system test, as described in the same manual, to see if each stage functions as it should.

    In recent years, Honeywell has become more vague in their description of features and options. Consequently, I can't say these options will definitely work, but with the blessing and assistance of your installer, it is worth a try. Don't change anything yourself. Your installer needs to agree with the proposed changes and be the one to make the changes so that he will be the one responsible for any problems. (Especially since it appears that he made a modification with a timer to get stage 2 working.)

    On the bright side, if this works, then I would argue that this was due to a setup error by the installer and you shouldn't be charges for the service call. The flip side is that if this doesn't work, you should pay for the service call.

    Maybe a pro here familiar with this thermostat would be kind enough to comment on the #176 setting. (Maybe Bergy or Curt knows?)
    __________

    Homeowner with WF Envision NDV038 (packaged) & NDZ026 (split), one 3000' 4 pipe closed horizontal ground loop, Prestige thermostats, desuperheaters, 85 gal. Marathon.
     
  10. bawalker

    bawalker New Member

    I would second that request for a professional opinion because I am confused about the settings for this thermostat. My installer insists it is set correctly but having to install a timer to make the 2nd stage come on seems really iffy to me. I am concerned about my unit's warranty.

    Thanks.
     
  11. Blake Clark

    Blake Clark Member

    I'm not familiar with this t-stat, but with my zoned system a 2nd stage "timer" is one of the programable options - not just a field-add-on-gizmo-workaround. It is for use where "aggressive upstaging is desired". The timer can be programmed to move to second stage if the call as not been satisfied after the programmed time in stage 1. It's typically used for sunrooms and other fast changing loads as a way to insure the system does't get too far behind the load. So at least the theory of a timed upstage is sound - in theory :D
     
  12. geome

    geome Member Forum Leader

    There is an easy way to find out if the thermostat is set correctly. Have the installer disable the timer, make no other changes, and have him run the thermostat system test, as described in the installation manual to see if each stage functions as it should.
     

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