Underslab sleeve size

Discussion in 'Vertical and Horizontal Loops' started by Lah72, Mar 5, 2017.

  1. Lah72

    Lah72 New Member

    I am planning on installing sleeves in my foundation to bring the field through the basement floor near the heat pump. My question is can you push (4) 3/4" pipes through a 4" 90 degree fitting? Do I need a large radius 90 or will the common radius such as the ones found at Lowe's or HD work? Any other tips or tricks is much appreciated. Thank you all in advance for your responses.
  2. arkie6

    arkie6 Active Member Forum Leader

    Four (3/4") pipes through a 4" standard PVC 90 will be tough. A long sweep would be better, but still not ideal because two pipes would try to occupy the outer radius of the bend while the other two pipes would have to fit inside the bend of the outer pipes. You should be able to get long sweep, say 24" or 36" radius, bends for grey 4" PVC conduit from your local electrical supply house, but they are spendy compared to 4" DWV PVC bends. Can you install two (2) 4" sleeves through the foundation so that you only have two (2) 3/4" pipes through each? That would work much better since both pipes would occupy the outside bend radius of the sleeve. One 4" sleeve for the supply pipes, and one 4" sleeve for the return pipes. Or what about a 45 deg bend with the sleeve coming up through the basement floor at a 45 deg angle, then cut flush with floor after the pour with an angle grinder?

    4" conduit sweep, 24" radius: https://www.platt.com/platt-electric-supply/PVC-Sweeps-90-/Multiple/4P90X24/product.aspx?zpid=51609
  3. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Why don't you stub in the 1.25" pipes below the foundation below the basement floor (before you pour it). Embed it a bit in sand. And let them come out where you place the heat pump. Done. No sleeves needed.
  4. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    We pull 2" hdpe through 4" electrical sweeps all the time. Tape your 3/4 pipes together in 1 bundle and pull away.
  5. Lah72

    Lah72 New Member

    I have a decent amount of experience with air source heat pumps (installations and repair/maintenance) but none with geothermal. With that being said, I do not have a fusion tool or flush cart. I am basically a DIYer when it comes to geothermal. I have done a lot of research and reading over that last year or so. Planning on installing a Bosch SM series system. Anyone have anything against them? Any better systems out there?

    I thought it would be easier to flush the loops with the manifold indoors so i could flush one loop at a time using the flow center. Is this true? Or can you successfully flush a system with the flow center and 1.25" pipe and all the connections underground?

    Another question...

    How do you all dig your loops? Trencher? Excavator?

    I talked to a contractor around here that trenches 600' of pipe in a 300' loop per ton. One on the bottom, push some dirt in the trench and take the pipe back. My problem is that i can not find a trencher around here that will trench much more than 4' deep. I was hoping to be around 5' for the bottom pipe. My other option is an excavator with a 2' or 3' bucket and put both pipes on the bottom of the trench. I am sure this is a slower dig process. Any suggestions?

    Thank you all for your time and recommendations.
    Last edited: Mar 5, 2017
  6. mtrentw

    mtrentw Active Member Industry Professional Forum Leader

    Any excavator to get you to 6 feet would be ideal.. If you have a 2 or 3 foot bucket, put supply and return on opposite sides of the trench. If you've got a 12" bucket, put supply at 6' add dirt and return at 4'-5'.
    waterpirate likes this.
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Then just stub in the 4 pipes underneath the foundation and route them to the place where you want to put the heatpump. No Sleeve needed. Or put a sleeve in and pull it through there.
  8. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Without sleeves, hdpe will gap away from concrete over time.
  9. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I yet have to see that.
    Again, I am talking about running the PE underneath the foundation walls, underneath the basement slab, only penetrating through the concrete in the heat pump location.

    If penetration directly through the basement wall, yes I would sleeve it, but running it underneath the floors gives us no trouble.
  10. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Local horror story I was not involved in.... HDPE was run beneath footer and slab in dirt, but not protected from the concrete were it day lighted in the mech. room. The heat generated from the curing concrete deformed the HDPE. It was a do-over for the installer. If taking Doc's route, be sure the pipes are protected from the concrete where they will be exposed to curing concrete.
  11. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Our code is anything within 10' of foundation is insulated. Also sleeves through concrete.

    I have seen older installs with gaps on pipes. Groundwater a possible concern with gaps, but we also have radon gas areas.

    Our preference is to run sub slab and bring up into mechanical room.
  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    No radon in our area, and the new builds are well drained. I hear what you are saying, just never a concern. Nor has the curing of the concrete ever deformed the pipes. I appreciate your concerns, it just has never been an issue. Have it done in my own house, (10) 3/4", coming up through the concrete.

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