vertical loop opnions wanted.

Discussion in 'Vertical and Horizontal Loops' started by TowPro, Feb 20, 2013.

  1. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    You can either drill another 100', which is almost boring, or you can get creative. Lets say you don't have much room, and you must get 200' ft of pipe in the ground before it goes down your borehole, and another 200' after it comes up again out of the hole, (400 ft total to get you the missing 1/2 ton capacity you need) you can built a 4' diameter slinky with 1.25" pipe with a 24" pitch. So you run a 25ft trench out to the well, overshoot by 5ft, run the pipe back to the well, and the return pipe coming back from the well you run in a second trench back to the house in the same way, right next to the first one. That way you could get 400ft of pipe into the ground in (2) 25ft trenches.
    Just a thought.
    Yes, you can run it in 1" pipe for 30ft (incl. hose) for supply and return, and then convert over to 1.25" pipe. Just confirm your heatloss and that it will be 2 ton unit.
  2. TowPro

    TowPro Member

    Building Component 1,221.8 sq.ft
    Sensible Gain (BTUH) 15,043
    Latent Gain (BTUH) 2,420
    Total heat Gain (BTUH) 17,463
    Total loss (BTUH) 22,831

    unit is a climatemaster Tranquility 30 Digital(TE) Series TE026
    Part load 41F EWT = 15300 Btuh (which is my Heat loss at 30F)
    Full load 32 EWT = 18900 Btuh (which is my heat loss at 21F)
    Full load 41F EWT = 22000 Btuh (which is my heat loss at 13F)
    (I got these different heat loss numbers by changing the design temp in the software. My area design temps are 11F).

    With 8KW backup electric heat, Aux balance point is 8 deg (as shown in GeoDesigner).

    the well is 75' away from the home Wall. I can get one 2' wide trench from home to well.
  3. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    OK, the numbers look good for a 2 ton system, your system seems to be relatively well balanced for the season. Actually it will be a bit heat dominated. Thus if you use highly conductive grout and 1.25" pipe, I don't see a reason why 200' of borehole should not be good enough. Dig the trench out to the well 6-8' deep and put the 1.25" pipe on opposite side of the trench, and you should be good to go. That way the trench itself gives you about 3/10 of a ton capacity.

    I ran it in looplink, and your min EWT in the winter would be 30.1F and your summer max would be 104F, and that is assuming a normal grout conductivity of 0.40. If you could run it out as a simple slinky, 325' out in a 75' trench, down in the borehole for 400', and straight back 75' from the borehole in the same trench, your summer max would go down to 94F.

    It is not the size of the heatpump which determines the size of the outside heat exchanger, it is the size of the annual and to a certain degree the temporary load which determines that. Use the trench going out to the borehole as your friend, and you still should be good to go with 200'. If you want to spend your money better, use highly conductive grout of 0.88 in the borehole, and your needed loop length goes down to 185' borehole length, and that is without the trench.

    Can you give us your zip code (I assume something like ROanoke, VI so far, with 12F design temp for winter? Deep earth ground temp?
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader


    Great idea. If one needs to dig a trench, fill it up with heat ex-changer pipe.

  5. TowPro

    TowPro Member

    19344, the surrounding area is around 500' above Sea level, but I am at 967', just off the west side of the peak, but my property is on the north/west exposure.
    my nearest city's are Lancaster PA, then a little further west is Harrisburg PA. While Philadelphia is 50 miles east of me, it tends to be a different climate about 5 deg hotter year round.

    I have been using 98 and 11 as my temp extremes. I think I have seen 11 once in the 20 years I have lived here, but we see 98 a couple times in the afternoon during the summer. but the numbers I look at is the heat side since it looks like the unit might never leave stage 1 in AC mode :)
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    OK, your temperatures seem to help you since you are slighly heating dominated.

    YOu have a couple options:

    1) you can use thermally enhanced grout (0.88) and you should be all fine with 200' of borehole (all 1.25"), giving you 29.9 F minimum temp and 91.5 F max temp.
    2) you can go with 0.40 standard grout, but then your min EWT goes down to 25F and your summer max could be 112F.
    3) put a additional 400' of horizontal pipe in as described before, which will get your min loop temp up to 29.8, and your summer max to 94.7F, both numbers which would work well for you.
    4) you could do both, grout your well with 0.88 grout, and 400' of pipe, that would get your loop up to 35.9 min, and 81.8F max. Not sure if I would do the effort and if you get a reasonable return for that investment.

    Or drill another well of 100', but that would be boring.

    I would do # 3, but the choice is yours. You would be rewarded with $440 for heating and cooling, and $212 for Domestic hot water for 3 users.

Share This Page