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Vertical Borehole Loop Sizing

Loop length, borehole count from load and soil type.

Boreholes go down 50โ€“150 m where land is tight โ€” rock conducts beautifully (~60 W/m). The bore count from this sizing drives 60% of project cost; soil test bores de-risk the estimate.

125 m
Loop pipe length needed
Heat drawn from ground7.5 kW
Extraction rate (Solid rock (borehole))60 W/m
Boreholes (100 m each)2
Land/depth check2 bores ร— 100 m, โ‰ฅ6 m apart

Vertical borehole field: the ground supplies the load minus the compressor's contribution. Undersized loops work the first season, then progressively freeze the ground and kill the COP โ€” size for the soil you actually have, and when in doubt, drill the test bore.

Sources: IGSHPA sizing guidance; soil extraction-rate tables (typical)

Engineering estimate from published standards and typical equipment data. Site conditions, equipment datasheets and measured data govern the real result โ€” confirm with a qualified engineer.

Use the free Vertical Borehole Loop Sizing online โ€” Loop length, borehole count from load and soil type. Runs instantly in your browser: no signup, no upload, mobile-friendly.

About Vertical Borehole Loop Sizing

Boreholes go down 50โ€“150 m where land is tight โ€” rock conducts beautifully (~60 W/m). The bore count from this sizing drives 60% of project cost; soil test bores de-risk the estimate.

How to use Vertical Borehole Loop Sizing

  1. 1Enter the peak heating/cooling load.
  2. 2Pick the ground type honestly (test bores beat guesses).
  3. 3Read pipe length and the boreholes or trench the config needs.

Why use Vertical Borehole Loop Sizing?

  • โœ“Soil-honest extraction rates: wet clay to dry sand spans 3ร—
  • โœ“Loop length, borehole count or trench length โ€” config-correct outputs
  • โœ“COP-aware: the ground supplies load minus compressor work
  • โœ“Undersizing warned against explicitly (frozen-loop death spiral)

Frequently asked questions

How long does a ground loop need to be?+

Pipe length = ground-side load รท soil extraction rate. A 10 kW system at COP 4 draws ~7.5 kW from ground; in damp loam (40 W/m) that's ~190 m of pipe โ€” two 100 m boreholes or ~95 m of two-pipe trench. Soil moisture moves this 3ร—, which is why the soil selector matters most.

Vertical boreholes or horizontal trenches?+

Land decides: horizontal costs less per metre (excavator vs drill rig) but needs yard area at 1.5โ€“2 m depth; boreholes go down 50โ€“150 m on a parking-space footprint and reach steadier temperatures. City sites drill; farms and large plots usually trench.

What happens if the loop is undersized?+

A slow-motion failure: the ground around the loop progressively freezes (heating) or bakes (cooling) season over season, COP slides, and the 'efficient' system becomes an expensive resistance heater by year three. Size for the soil you have โ€” and when in doubt, drill the test bore.

Does geothermal make sense in India?+

For cooling, increasingly: rejecting heat into 27ยฐC earth instead of 45ยฐC summer air lifts efficiency 30โ€“50% for the same machine. Large buildings with land (campuses, hospitals) pencil first. The loop sizing here works both directions โ€” size for the dominant (cooling) load.

Embed Vertical Borehole Loop Sizing on your website

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